Favorite reverse bias protection for battery circuits
Charlie E.
Still working on my color reader, and getting close. Biggest problem
is that now I have almost TOO much drive on my LEDs, but that I can
deal with!
Now, to the latest problem. My system is for the visually impaired. I
just put the batteries in one of my prototypes backwards, and it
didn't last very long. While I expect this device to have very long
battery life, since it normally doesn't operate but for a second or
two, it looks like the MC1253's don't like getting reversed biased
very long. So, for my design question of the day - What is your
favorite circuit for preventing reverse bias from the batteries? The
old diode trick drops too much voltage, so wondered if there are any
clever FET tricks to block backwards voltages.
Thanks!
Charlie
BillyGates
Yes, there are fet "tricks" that when reverse biased bias the fet to turn it
off. It is essentially an "active diode".
Hammy
wrote:
I usually use #2 on this page a shorting shottky.
Rich Webb
wrote:
>Hi All,
This http://www.maxim-ic.com/app-notes/index.mvp/id/636 Maxim appnote
describes the pros and cons of several standard approaches.
--
Rich Webb Norfolk, VA
Joerg
That renders the unit dead and a blind or almost blind person will have
a hard time finding or buying the proper fuse and installing it.
Charlie: Solution #3 is the ticket (look on Hammy's link). But make sure
that the FET is guaranteed to be fully turned on at the lowest allowed
battery voltage, IOW the point where an UVLO comes on.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
linnix
> Hi All,
> Still working on my color reader, and getting close. Biggest problem
> is that now I have almost TOO much drive on my LEDs, but that I can
> deal with!
>
> Now, to the latest problem. My system is for the visually impaired. I
> just put the batteries in one of my prototypes backwards, and it
> didn't last very long.
I believe that's why they invented LCD to save power. Not sure how
well it can be read by visually impaired.
> While I expect this device to have very long
> battery life, since it normally doesn't operate but for a second or
> two, it looks like the MC1253's don't like getting reversed biased
> very long. So, for my design question of the day - What is your
> favorite circuit for preventing reverse bias from the batteries? The
> old diode trick drops too much voltage, so wondered if there are any
> clever FET tricks to block backwards voltages.
LCD controllers are usually less sensitive to supply voltage than LED
drivers. LCD segments need almost zero currents.
>
> Thanks!
>
> Charlie
Jim Thompson
wrote:
>Hi All,
Some variation on this...
http://analog-innovations.com/SED/PerfectDiodeForChargerIsolation.pdf
Do you have enough voltage to turn on MOSFET's?
Probably could do it with bipolar's... I'll ponder :-)
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The only thing bipartisan in this country is hypocrisy
Joerg
> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmo...@ieee.org>
> wrote:
>
>> Hi All,
>> Still working on my color reader, and getting close. Biggest problem
>> is that now I have almost TOO much drive on my LEDs, but that I can
>> deal with!
>>
>> Now, to the latest problem. My system is for the visually impaired. I
>> just put the batteries in one of my prototypes backwards, and it
>> didn't last very long. While I expect this device to have very long
>> battery life, since it normally doesn't operate but for a second or
>> two, it looks like the MC1253's don't like getting reversed biased
>> very long. So, for my design question of the day - What is your
>> favorite circuit for preventing reverse bias from the batteries? The
>> old diode trick drops too much voltage, so wondered if there are any
>> clever FET tricks to block backwards voltages.
>>
>> Thanks!
>>
>> Charlie
>
> Some variation on this...
>
> http://analog-innovations.com/SED/PerfectDiodeForChargerIsolation.pdf
>
> Do you have enough voltage to turn on MOSFET's?
>
> Probably could do it with bipolar's... I'll ponder :-)
>
Which HV CMOS process did that get rolled onto, if I may ask?
Jim Thompson
wrote:
>Jim Thompson wrote:
>> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmo...@ieee.org>
>> wrote:
>>
>>> Hi All,
>>> Still working on my color reader, and getting close. Biggest problem
>>> is that now I have almost TOO much drive on my LEDs, but that I can
>>> deal with!
>>>
>>> Now, to the latest problem. My system is for the visually impaired. I
>>> just put the batteries in one of my prototypes backwards, and it
>>> didn't last very long. While I expect this device to have very long
>>> battery life, since it normally doesn't operate but for a second or
>>> two, it looks like the MC1253's don't like getting reversed biased
>>> very long. So, for my design question of the day - What is your
>>> favorite circuit for preventing reverse bias from the batteries? The
>>> old diode trick drops too much voltage, so wondered if there are any
>>> clever FET tricks to block backwards voltages.
>>>
>>> Thanks!
>>>
>>> Charlie
>>
>> Some variation on this...
>>
>> http://analog-innovations.com/SED/PerfectDiodeForChargerIsolation.pdf
>>
>> Do you have enough voltage to turn on MOSFET's?
>>
>> Probably could do it with bipolar's... I'll ponder :-)
>>
>
>Which HV CMOS process did that get rolled onto, if I may ask?
California Micro Devices (do they still exist?) for a LiIon
charge/discharge controller.
D Yuniskis
Solve this problem *mechanically*. You need to prevent the
batteries from being *installed* wrong, in the first place.
E.g., any sort of circuit that protects (the rest of) the
circuit from reversed battery won't do anything to tell the
VI user *why* your device isn't working. Are the batteries
*dead*? Installed wrong? Corroded terminals? Or is the
*device* broken??
"Key" the battery holder so the user can feel the correct
orientation for the batteries *and* so it prevents the
cells from making electrical contact if not oriented
properly.
Think of how the *user* is going to interact with your device.
Close your eyes and "figure out" why it doesn't work :-/
Hammy
wrote:
>Hammy wrote:
>> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmo...@ieee.org>
>> wrote:
>>
>>> Hi All,
>>> Still working on my color reader, and getting close. Biggest problem
>>> is that now I have almost TOO much drive on my LEDs, but that I can
>>> deal with!
>>>
>>> Now, to the latest problem. My system is for the visually impaired. I
>>> just put the batteries in one of my prototypes backwards, and it
>>> didn't last very long. While I expect this device to have very long
>>> battery life, since it normally doesn't operate but for a second or
>>> two, it looks like the MC1253's don't like getting reversed biased
>>> very long. So, for my design question of the day - What is your
>>> favorite circuit for preventing reverse bias from the batteries? The
>>> old diode trick drops too much voltage, so wondered if there are any
>>> clever FET tricks to block backwards voltages.
>>>
>>> Thanks!
>>>
>>> Charlie
>> I usually use #2 on this page a shorting shottky.
>>
>> http://www.recom-international.com/press/Reverse%20Polarity%20Protection%20for%20DC/DC%20Converters.html
>
>
>That renders the unit dead and a blind or almost blind person will have
>a hard time finding or buying the proper fuse and installing it.
Thats what they have seeing eye dogs for:-) Jokeing.
Of course your right for a blind person either #3 or a keyed battery
connection. With a brail instruction manual
Joerg
Swallowed by ON, just like AMI was :-(
Joerg
Ok, I'll ask our new Labrador when she is back :-)
She went through the first three phases of guide dog training and then
had to be discharged for a medical condition (soft trachea, happens a
lot with guide dog Labs).
> Of course your right for a blind person either #3 or a keyed battery
> connection. With a brail instruction manual
>
It's actually even better these days. A nearly blind relative has a
Casio watch that talks.
>> Charlie: Solution #3 is the ticket (look on Hammy's link). But make sure
>> that the FET is guaranteed to be fully turned on at the lowest allowed
>> battery voltage, IOW the point where an UVLO comes on.
Charlie E.
Would be the best result, but these are standard AA cells, no way to
key them without using expensive custom battery packs. Not the way to
go for inexpensive...
Will be looking for a good PMOS FET that will still conduct with two
low AA batteries, probably around 1.8VDC, if they make one! ;-)
Thanks All!
Charlie
D Yuniskis
I take it you aren't making a custom (molded) case?
Why not purchase COTS battery holder that *is* "keyed"?
> Will be looking for a good PMOS FET that will still conduct with two
> low AA batteries, probably around 1.8VDC, if they make one! ;-)
If you go that route, consider how your design can tell the user
"yes, I am working" vs. absence of that indication so the user
can deduce "something is wrong with the batteries or their
installation" (or the device)
Jim Thompson
wrote:
>On Tue, 16 Mar 2010 12:15:25 -0700, D Yuniskis
Called a PNP :-)
What's the load current?
Hammy
wrote:
>>> That renders the unit dead and a blind or almost blind person will have
>>> a hard time finding or buying the proper fuse and installing it.
>> Thats what they have seeing eye dogs for:-) Jokeing.
>>
>
>Ok, I'll ask our new Labrador when she is back :-)
>
>She went through the first three phases of guide dog training and then
>had to be discharged for a medical condition (soft trachea, happens a
>lot with guide dog Labs).
Are you a foster dad for pups?
You must dread having to give them up?
I just took my Golden Retriever to the vet. He started to develop a
sunken eye. The vet doesn't know the cause yet. I'm hoping its nothing
to serious.
>
>> Of course your right for a blind person either #3 or a keyed battery
>> connection. With a brail instruction manual
>>
>
>It's actually even better these days. A nearly blind relative has a
>Casio watch that talks.
That's nothing look at Hawkins chair that dude is wired for sound and
then some. :-)
Joerg
> On Tue, 16 Mar 2010 12:42:56 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>
>>>> That renders the unit dead and a blind or almost blind person will have
>>>> a hard time finding or buying the proper fuse and installing it.
>>> Thats what they have seeing eye dogs for:-) Jokeing.
>>>
>> Ok, I'll ask our new Labrador when she is back :-)
>>
>> She went through the first three phases of guide dog training and then
>> had to be discharged for a medical condition (soft trachea, happens a
>> lot with guide dog Labs).
>
> Are you a foster dad for pups?
> You must dread having to give them up?
>
No, we are puppy sitters. So we jump in when a family goes on vacation
or visits a sick relative where they can't take the guide dog puppy.
Even then it's tough when they have to go back to San Rafael, especially
for my wife since she sees them every week during trainings. But when
you see them paired up with a blind person you know it's all worth it.
We used to also sit the one that came home now. She instantly remembered
our other dogs, where everything is in the house, etc.
> I just took my Golden Retriever to the vet. He started to develop a
> sunken eye. The vet doesn't know the cause yet. I'm hoping its nothing
> to serious.
Hopefully not. Our Rottweiler is now at an age where it's just a matter
of time :-(
>>> Of course your right for a blind person either #3 or a keyed battery
>>> connection. With a brail instruction manual
>>>
>> It's actually even better these days. A nearly blind relative has a
>> Casio watch that talks.
>
> That's nothing look at Hawkins chair that dude is wired for sound and
> then some. :-)
>
No idea what a Hawkins chair is.
<scratching_head>
[...]
Charlie E.
wrote:
He's talking Stephen Hawkins (sp?) the physicist with MS.
Well, my wife's computer talks to her, she has two watches that talk
(one red, one blue) a talking calculator that includes a calendar and
timer function, and another talking calculator that just does math...
Charlie
Hammy
wrote:
>
>> I just took my Golden Retriever to the vet. He started to develop a
>> sunken eye. The vet doesn't know the cause yet. I'm hoping its nothing
>> to serious.
>
>
>Hopefully not. Our Rottweiler is now at an age where it's just a matter
>of time :-(
Mine just turned 9. My last one was 11 when he died.
>
>>>> Of course your right for a blind person either #3 or a keyed battery
>>>> connection. With a brail instruction manual
>>>>
>>> It's actually even better these days. A nearly blind relative has a
>>> Casio watch that talks.
>>
>> That's nothing look at Hawkins chair that dude is wired for sound and
>> then some. :-)
>>
>
>No idea what a Hawkins chair is.
>
><scratching_head>
>
>[...]
He's that British theoretical physicist who came up with a theory for
the origin of the universe among other things.
http://en.wikipedia.org/wiki/Stephen_Hawking
He has amyotrophic lateral sclerosis. So he uses a chair with all
sorts of gadgets on it.
Joerg
Ah yes, Stephen Hawking:
http://en.wikipedia.org/wiki/Stephen_Hawking
> Well, my wife's computer talks to her, she has two watches that talk
> (one red, one blue) a talking calculator that includes a calendar and
> timer function, and another talking calculator that just does math...
>
Once a disabled person masters technology it can add so much to their
abilities.
Same with non-tech skills. A neighbor is deaf and he and his brothers
can "talk" from vehicle to vehicle without any technology, by signing.
It's amazing. But he also uses video phones etc.
Joerg
Anything other than AA cells is expensive. And as Charlie wrote AA cells
are difficult to key without going to precision molding or milling.
>> Will be looking for a good PMOS FET that will still conduct with two
>> low AA batteries, probably around 1.8VDC, if they make one! ;-)
>
> If you go that route, consider how your design can tell the user
> "yes, I am working" vs. absence of that indication so the user
> can deduce "something is wrong with the batteries or their
> installation" (or the device)
Very easy: Oscillator that is connected via a diode so it works only
when batteries are reversed, drives piezo. Battery inserted the wrong
way -> beep ... beep ... beep ...
If you want to also cover the case where only one of the batteries is
reversed use two of those, can drive the same piezo.
Joerg
Why PMOS?
D Yuniskis
Joerg wrote:
> D Yuniskis wrote:
>>>> Solve this problem *mechanically*. You need to prevent the
>>>> batteries from being *installed* wrong, in the first place.
>>>> E.g., any sort of circuit that protects (the rest of) the
>>>> circuit from reversed battery won't do anything to tell the
>>>> VI user *why* your device isn't working. Are the batteries
>>>> *dead*? Installed wrong? Corroded terminals? Or is the
>>>> *device* broken??
>>>>
>>>> "Key" the battery holder so the user can feel the correct
>>>> orientation for the batteries *and* so it prevents the
>>>> cells from making electrical contact if not oriented
>>>> properly.
>>>>
>>>> Think of how the *user* is going to interact with your device.
>>>> Close your eyes and "figure out" why it doesn't work :-/
>>>
>>> Would be the best result, but these are standard AA cells, no way to
>>> key them without using expensive custom battery packs. Not the way to
>>> go for inexpensive...
>>
>> I take it you aren't making a custom (molded) case?
>> Why not purchase COTS battery holder that *is* "keyed"?
>
> Anything other than AA cells is expensive. And as Charlie wrote AA cells
> are difficult to key without going to precision molding or milling.
Yes. Find a battery holder that someone *else* has incurred
the cost of that molding! Preferably, something that lets
the user access the "battery compartment" without having
to disassemble the device itself.
OTOH, if he is making "one off", a bit of plastic glued on either
side of the '+' holder terminal can do the trick.
I'd also look for those (camera?) batteries (two cells side
by side... 3V?) as I think that is keyed (at the very
least, it eliminates the problem of putting one cell in
correct and one backwards)
>>> Will be looking for a good PMOS FET that will still conduct with two
>>> low AA batteries, probably around 1.8VDC, if they make one! ;-)
>>
>> If you go that route, consider how your design can tell the user
>> "yes, I am working" vs. absence of that indication so the user
>> can deduce "something is wrong with the batteries or their
>> installation" (or the device)
>
> Very easy: Oscillator that is connected via a diode so it works only
> when batteries are reversed, drives piezo. Battery inserted the wrong
> way -> beep ... beep ... beep ...
>
> If you want to also cover the case where only one of the batteries is
> reversed use two of those, can drive the same piezo.
You don't need to be that extravagant. Just something in the
*normal* usage of the device that people can count on for
feedback/confirmation. E.g., if the device uses audio
output (synthetic speech or just "tones"), then design
the device so that immediately on turning on, it "chirps"
once.
[I don't recall what he has chosen for his output medium;
personally, I would opt for limited vocabulary speech as
it can be *very* small]
This gives a positive indication to the user in *normal*
operation (i.e., those times when you HAVEN'T just
changed batteries) that the device is, in fact, "on".
And, knowing to expect this, it can be used when replacing
batteries to act as a confirmation that the batteries
are, in fact, installed correctly, aren't "dead", etc.
Joerg
Very tough. I had tried that at times in the past and there ain't much
out there. Even the ready-to-go enclosures with built-in compartment
that I came across aren't really good in that respect.
> OTOH, if he is making "one off", a bit of plastic glued on either
> side of the '+' holder terminal can do the trick.
>
> I'd also look for those (camera?) batteries (two cells side
> by side... 3V?) as I think that is keyed (at the very
> least, it eliminates the problem of putting one cell in
> correct and one backwards)
>
I have one, in case of a trip way into the boonies (those are Li
batteries so they'll last longer). Very expensive, not really an option
for everyday use.
Yes, that's usually good enough. No audio feedback -> something must be
wrong with the batteries.
Jim Thompson
wrote:
>Hi All,
See...
Newsgroups: alt.binaries.schematics.electronic
Subject: Battery Reversal Protection (from SED) -
BatteryReversalProtection.pdf
Date: Tue, 16 Mar 2010 15:32:36 -0700
Message-ID: <6l10q59eb80bgcp4g...@4ax.com>
But pick a better transistor, with lower saturation. I don't store
discrete transistor data in my head like I do ASIC processes :-)
Martin Riddle
"Joerg" <inv...@invalid.invalid> wrote in message
news:80a0b7...@mid.individual.net...
You can replace the fuse with a PTC, batteries might not like it, but it
would still function when the batteries are inserted correctly.
Cheers
D Yuniskis
I've been eying the Bulgin products. MPD and Keystone
tend to be bottom feeder designs which haven't impressed
me. But, I'm currently designing for much higher power
requirements so batteries (at least standard cells)
aren't an option.
>> OTOH, if he is making "one off", a bit of plastic glued on either
>> side of the '+' holder terminal can do the trick.
>>
>> I'd also look for those (camera?) batteries (two cells side
>> by side... 3V?) as I think that is keyed (at the very
>> least, it eliminates the problem of putting one cell in
>> correct and one backwards)
>
> I have one, in case of a trip way into the boonies (those are Li
> batteries so they'll last longer). Very expensive, not really an option
> for everyday use.
Are you sure? The ones I have are made by Duracell (though
none of them are in convenient places for me to examine).
I would imagine a "colorimeter" sees infrequent use so
you would want a battery that's going to be "there for you"...
(My pet peeve re: flashlights is you use them so infrequently
that the batteries are *always* dead when you need them)
*If* the audio feedback in normal operation is noticeable
enough. E.g., audio annunciators in most *cars* are
ineffective as: 1) there are too many of them 2) they
don't "complain" enough.
I.e., make the "chirp" something distinctive (a little
tune) so it's noticeable without being obnoxious -- and
"missed" when absent.
E.g., you could power up a Windows PC with your eyes closed
and would "notice" if their silly little tune didn't play...
Jim Thompson
Of course, if you can get that proverbial PMOS with VT=0.7V, as I can
in ASIC's, you'd do this...
Newsgroups: alt.binaries.schematics.electronic
Subject: Re: Battery Reversal Protection (from SED) -
BatteryReversalProtection.pdf - BatteryReversalProtection-2.pdf
Date: Tue, 16 Mar 2010 15:51:15 -0700
Message-ID: <om20q55rp2gcfo182...@4ax.com>
Vladimir Vassilevsky
Charlie E. wrote:
> Hi All,
> Still working on my color reader, and getting close. Biggest problem
> is that now I have almost TOO much drive on my LEDs, but that I can
> deal with!
>
> Now, to the latest problem. My system is for the visually impaired. I
> just put the batteries in one of my prototypes backwards, and it
> didn't last very long. While I expect this device to have very long
> battery life, since it normally doesn't operate but for a second or
> two, it looks like the MC1253's don't like getting reversed biased
> very long. So, for my design question of the day - What is your
> favorite circuit for preventing reverse bias from the batteries? The
> old diode trick drops too much voltage, so wondered if there are any
> clever FET tricks to block backwards voltages.
I like LTC4358.
They took care of a lot of problems typical for trivial DIY reverse
battery protection circuits.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
k...@att.bizzzzzzzzzzzz
>Hi All,
>Still working on my color reader, and getting close. Biggest problem
>is that now I have almost TOO much drive on my LEDs, but that I can
>deal with!
>
>Now, to the latest problem. My system is for the visually impaired. I
>just put the batteries in one of my prototypes backwards, and it
>didn't last very long. While I expect this device to have very long
>battery life, since it normally doesn't operate but for a second or
>two, it looks like the MC1253's don't like getting reversed biased
>very long. So, for my design question of the day - What is your
>favorite circuit for preventing reverse bias from the batteries? The
>old diode trick drops too much voltage, so wondered if there are any
>clever FET tricks to block backwards voltages.
A plastic slot that the '+' end of the battery fits nicely into but such that
the '-' end doesn't make contact?
Jan Panteltje
<inv...@invalid.invalid> wrote in <80abo8...@mid.individual.net>:
>Very easy: Oscillator that is connected via a diode so it works only
>when batteries are reversed, drives piezo. Battery inserted the wrong
>way -> beep ... beep ... beep ...
Clever.
>If you want to also cover the case where only one of the batteries is
>reversed use two of those, can drive the same piezo.
Use a bigger batteriy and a bridge rectifier,
then it does not matter how they are put in.
Joerg
Their battery holders don't look particularly well keyed either:
http://www.bulgin.co.uk/Products/BatteryHolders/BatteryHolders.html
>>> OTOH, if he is making "one off", a bit of plastic glued on either
>>> side of the '+' holder terminal can do the trick.
>>>
>>> I'd also look for those (camera?) batteries (two cells side
>>> by side... 3V?) as I think that is keyed (at the very
>>> least, it eliminates the problem of putting one cell in
>>> correct and one backwards)
>>
>> I have one, in case of a trip way into the boonies (those are Li
>> batteries so they'll last longer). Very expensive, not really an
>> option for everyday use.
>
> Are you sure? ...
Yup:
http://www.atbatt.com/product/14514.asp
> ... The ones I have are made by Duracell (though
> none of them are in convenient places for me to examine).
> I would imagine a "colorimeter" sees infrequent use so
> you would want a battery that's going to be "there for you"...
> (My pet peeve re: flashlights is you use them so infrequently
> that the batteries are *always* dead when you need them)
>
That's why everyone here knows where the spares are. There are also
spare flashlights.
It's the first thing I disable when I get a new PC :-)
D Yuniskis
Jan Panteltje wrote:
> Use a bigger batteriy and a bridge rectifier,
> then it does not matter how they are put in.
The device ends up larger. And weighs more, etc.
For *one* device, this is no big deal. But, folks with
disabilities tend to have *lots* of "special devices".
Each is typically larger than it's counterpart (for
the mainstream population).
D Yuniskis
Joerg wrote:
>>>>>> I take it you aren't making a custom (molded) case?
>>>>>> Why not purchase COTS battery holder that *is* "keyed"?
>>>>>
>>>>> Anything other than AA cells is expensive. And as Charlie wrote AA
>>>>> cells are difficult to key without going to precision molding or
>>>>> milling.
>>>>
>>>> Yes. Find a battery holder that someone *else* has incurred
>>>> the cost of that molding! Preferably, something that lets
>>>> the user access the "battery compartment" without having
>>>> to disassemble the device itself.
>>>
>>> Very tough. I had tried that at times in the past and there ain't
>>> much out there. Even the ready-to-go enclosures with built-in
>>> compartment that I came across aren't really good in that respect.
>>
>> I've been eying the Bulgin products. MPD and Keystone
>> tend to be bottom feeder designs which haven't impressed
>> me. But, I'm currently designing for much higher power
>> requirements so batteries (at least standard cells)
>> aren't an option.
>
> Their battery holders don't look particularly well keyed either:
>
> http://www.bulgin.co.uk/Products/BatteryHolders/BatteryHolders.html
I've been through their site and haven't been able to find
any mechanical drawings *or* photos that show enough detail
to decide. I have a few on my next Digikey order just to
"evaluate" -- though it would be hard to come to a conclusive
decision for *all* of their products based on a sampling of
a few... (if I like the quality -- touch and feel -- I will
followup with a call to the manufacturer)
>>>> OTOH, if he is making "one off", a bit of plastic glued on either
>>>> side of the '+' holder terminal can do the trick.
>>>>
>>>> I'd also look for those (camera?) batteries (two cells side
>>>> by side... 3V?) as I think that is keyed (at the very
>>>> least, it eliminates the problem of putting one cell in
>>>> correct and one backwards)
>>>
>>> I have one, in case of a trip way into the boonies (those are Li
>>> batteries so they'll last longer). Very expensive, not really an
>>> option for everyday use.
>>
>> Are you sure? ...
>
> Yup:
>
> http://www.atbatt.com/product/14514.asp
No, that's not the same battery. I'll have to find one of mine
and see what size it claims to be...
>> ... The ones I have are made by Duracell (though
>> none of them are in convenient places for me to examine).
>> I would imagine a "colorimeter" sees infrequent use so
>> you would want a battery that's going to be "there for you"...
>> (My pet peeve re: flashlights is you use them so infrequently
>> that the batteries are *always* dead when you need them)
>
> That's why everyone here knows where the spares are. There are also
> spare flashlights.
We now use "emergency flashlights". I've disciplined myself
to give each one a "quick wind" whenever I come across one
just to keep the battery fresh.
I recently came across one of these "emergency" devices
that stores energy *mechanically* -- no more dependence
on Li cells (going bad from lack of use). I need to
see what other offerings they have.
Joerg
Yeah, their "datasheets" are not much to write home about.
>>>>> OTOH, if he is making "one off", a bit of plastic glued on either
>>>>> side of the '+' holder terminal can do the trick.
>>>>>
>>>>> I'd also look for those (camera?) batteries (two cells side
>>>>> by side... 3V?) as I think that is keyed (at the very
>>>>> least, it eliminates the problem of putting one cell in
>>>>> correct and one backwards)
>>>>
>>>> I have one, in case of a trip way into the boonies (those are Li
>>>> batteries so they'll last longer). Very expensive, not really an
>>>> option for everyday use.
>>>
>>> Are you sure? ...
>>
>> Yup:
>>
>> http://www.atbatt.com/product/14514.asp
>
> No, that's not the same battery. I'll have to find one of mine
> and see what size it claims to be...
>
But that's what you need when you want to replace two AA's. And you can
still reverse it.
>>> ... The ones I have are made by Duracell (though
>>> none of them are in convenient places for me to examine).
>>> I would imagine a "colorimeter" sees infrequent use so
>>> you would want a battery that's going to be "there for you"...
>>> (My pet peeve re: flashlights is you use them so infrequently
>>> that the batteries are *always* dead when you need them)
>>
>> That's why everyone here knows where the spares are. There are also
>> spare flashlights.
>
> We now use "emergency flashlights". I've disciplined myself
> to give each one a "quick wind" whenever I come across one
> just to keep the battery fresh.
>
We have two of those as well. But I am afraid there's just a puny NiCd
in there which will die some day, plus it has very little runtime per
charge. The old D-cell lights can go for hours. Ok, they don't have a
built-in NOAA radio.
> I recently came across one of these "emergency" devices
> that stores energy *mechanically* -- no more dependence
> on Li cells (going bad from lack of use). I need to
> see what other offerings they have.
I was (so far) rather disappointed by all this alternative stuff. It all
broke in due course. Nothing beats the old 2-cell $2.99 flashlight. Ok,
on the job I also carry a tiny MagLite Solitaire that needs only one
AAA. That has saved the day quite a few times. PHUT .. *BOOM* ... "S..t!
I can't see anything and somethin's glowing over here!" ... "Wait, I've
got a li'l lamp"
D Yuniskis
Joerg wrote:
>> I recently came across one of these "emergency" devices
>> that stores energy *mechanically* -- no more dependence
>> on Li cells (going bad from lack of use). I need to
>> see what other offerings they have.
>
> I was (so far) rather disappointed by all this alternative stuff. It all
> broke in due course.
Yup. "Plastic". Designed to appeal as "impulse buys".
> Nothing beats the old 2-cell $2.99 flashlight. Ok,
> on the job I also carry a tiny MagLite Solitaire that needs only one
> AAA. That has saved the day quite a few times. PHUT .. *BOOM* ... "S..t!
> I can't see anything and somethin's glowing over here!" ... "Wait, I've
> got a li'l lamp"
I just want something for my bugout-bag that I can rely on
*without* having to worry that some component (e.g., a
battery *buried* inside the "emergency light") has died
because it's been in storage for 10 years... I *think*
this thing will work good as there are no "components"
that I'd have to worry about crapping out (just the little
DC "motor/generator" and a bunch of mechanical bits)
What good are emergency devices if you can't rely on
them in an emergency?? :>
Joerg
> Hi Joerg,
>
> Joerg wrote:
[...]
>> Nothing beats the old 2-cell $2.99 flashlight. Ok, on the job I also
>> carry a tiny MagLite Solitaire that needs only one AAA. That has saved
>> the day quite a few times. PHUT .. *BOOM* ... "S..t! I can't see
>> anything and somethin's glowing over here!" ... "Wait, I've got a li'l
>> lamp"
>
> I just want something for my bugout-bag that I can rely on
> *without* having to worry that some component (e.g., a
> battery *buried* inside the "emergency light") has died
> because it's been in storage for 10 years... I *think*
> this thing will work good as there are no "components"
> that I'd have to worry about crapping out (just the little
> DC "motor/generator" and a bunch of mechanical bits)
>
> What good are emergency devices if you can't rely on
> them in an emergency?? :>
That's what preventive maintenance is for :-)
Seriously, we religiously replace the smoke detector batteries twice a
year, my lab stuff is also done regularly, and so on. With flashlights
there are a few that always get exchanged when the regular-use one dims
out and their batteries get installed in the regular-use flashlight. So
there is a rotation scheme. Same with smoke detector batteries, they are
used up in the voltmeters, the radios I use for EMI work and so on. IOW
in gear where a low-bat situation is ok but used often enough that it
won't leak from old age. This way only depleted batteries are discarded,
nothing goes to waste.
D Yuniskis
>> I just want something for my bugout-bag that I can rely on
>> *without* having to worry that some component (e.g., a
>> battery *buried* inside the "emergency light") has died
>> because it's been in storage for 10 years... I *think*
>> this thing will work good as there are no "components"
>> that I'd have to worry about crapping out (just the little
>> DC "motor/generator" and a bunch of mechanical bits)
>>
>> What good are emergency devices if you can't rely on
>> them in an emergency?? :>
>
> That's what preventive maintenance is for :-)
Bug out bag isn't something that sits in a prominent
position in the house. I.e., you've got to go *looking*
for it. And, hopefully, *never* need it. (out of sight,
out of mind)
> Seriously, we religiously replace the smoke detector batteries twice a
> year, my lab stuff is also done regularly, and so on. With flashlights
Aside from smoke detectors, we don't use anything with
replaceable batteries, here. No, I take that back,
the remote control for TV, etc.
Smoke/CO/Heat detectors are AC+DC. I think the battery is
not used -- though tested once a minute? -- in normal
operation. Replace on New Year's eve.
Anything else with a battery tends to be rechargeable
(iPods, PDAs, etc.). And, those batteries are silly to
replace as I can often rescue a replacement for the
entire device instead of paying as much for a "new"
battery :-/
Joerg
> Joerg wrote:
>>> I just want something for my bugout-bag that I can rely on
>>> *without* having to worry that some component (e.g., a
>>> battery *buried* inside the "emergency light") has died
>>> because it's been in storage for 10 years... I *think*
>>> this thing will work good as there are no "components"
>>> that I'd have to worry about crapping out (just the little
>>> DC "motor/generator" and a bunch of mechanical bits)
>>>
>>> What good are emergency devices if you can't rely on
>>> them in an emergency?? :>
>>
>> That's what preventive maintenance is for :-)
>
> Bug out bag isn't something that sits in a prominent
> position in the house. I.e., you've got to go *looking*
> for it. And, hopefully, *never* need it. (out of sight,
> out of mind)
>
Ahm, what about the food items in there? Just imagine, you and your
family have successfully evacuated. Now dad does the manly thing and
starts the fire. Mom pulls out a can of Progresso, says 'Best before
1998' on there, puts in can opener ... *POOF* .. *SPLAT* ... a horrid
stench wafts through the area ... "Oh, maybe that's why the can was
bulging" :-)
[...]
MooseFET
> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmond...@ieee.org>
> wrote:
>
>
>
> >Hi All,
> >Still working on my color reader, and getting close. Biggest problem
> >is that now I have almost TOO much drive on my LEDs, but that I can
> >deal with!
>
> >Now, to the latest problem. My system is for the visually impaired. I
> >just put the batteries in one of my prototypes backwards, and it
> >didn't last very long. While I expect this device to have very long
> >battery life, since it normally doesn't operate but for a second or
> >two, it looks like the MC1253's don't like getting reversed biased
> >very long. So, for my design question of the day - What is your
> >favorite circuit for preventing reverse bias from the batteries? The
> >old diode trick drops too much voltage, so wondered if there are any
> >clever FET tricks to block backwards voltages.
>
>
> >Charlie
>
> I usually use #2 on this page a shorting shottky.
>
I never use the shorting diode method. A blown fuse makes the
equipment
"DOA" and gets it sent back.
MooseFET
> Hi All,
> Still working on my color reader, and getting close. Biggest problem
> is that now I have almost TOO much drive on my LEDs, but that I can
> deal with!
>
> Now, to the latest problem. My system is for the visually impaired. I
> just put the batteries in one of my prototypes backwards, and it
> didn't last very long. While I expect this device to have very long
> battery life, since it normally doesn't operate but for a second or
> two, it looks like the MC1253's don't like getting reversed biased
> very long. So, for my design question of the day - What is your
> favorite circuit for preventing reverse bias from the batteries? The
> old diode trick drops too much voltage, so wondered if there are any
> clever FET tricks to block backwards voltages.
>
I did a quick check and nobody mentioned the idea of a diode in
series
with a relay coil.
> Thanks!
>
> Charlie
D Yuniskis
> D Yuniskis wrote:
>> Joerg wrote:
>>>> I just want something for my bugout-bag that I can rely on
>>>> *without* having to worry that some component (e.g., a
>>>> battery *buried* inside the "emergency light") has died
>>>> because it's been in storage for 10 years... I *think*
>>>> this thing will work good as there are no "components"
>>>> that I'd have to worry about crapping out (just the little
>>>> DC "motor/generator" and a bunch of mechanical bits)
>>>>
>>>> What good are emergency devices if you can't rely on
>>>> them in an emergency?? :>
>>>
>>> That's what preventive maintenance is for :-)
>>
>> Bug out bag isn't something that sits in a prominent
>> position in the house. I.e., you've got to go *looking*
>> for it. And, hopefully, *never* need it. (out of sight,
>> out of mind)
>
> Ahm, what about the food items in there? Just imagine, you and your
No food items. Keep canned goods in the cupboard
and *remember* to take some on your way out the door :>
Of course, the whole purpose is *not* to need these things!
Otherwise, one should *invest* properly in them! :-/
Grant
Kodak had a camera powered by a pair of AA NiMH cells glued into a plastic
holder.
Grant
That's because a relay coil likely draws more power than the circuit you're
trying to protect ;)
I like diode and polyswitch, or MOSFET circuit.
Grant.
Don Lancaster
> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmo...@ieee.org> wrote:
>
>> Hi All,
>> Still working on my color reader, and getting close. Biggest problem
>> is that now I have almost TOO much drive on my LEDs, but that I can
>> deal with!
>>
>> Now, to the latest problem. My system is for the visually impaired. I
>> just put the batteries in one of my prototypes backwards, and it
>> didn't last very long. While I expect this device to have very long
>> battery life, since it normally doesn't operate but for a second or
>> two, it looks like the MC1253's don't like getting reversed biased
>> very long. So, for my design question of the day - What is your
>> favorite circuit for preventing reverse bias from the batteries? The
>> old diode trick drops too much voltage, so wondered if there are any
>> clever FET tricks to block backwards voltages.
Synchronous rectifier.
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: d...@tinaja.com
Please visit my GURU's LAIR web site at http://www.tinaja.com
Jan Panteltje
<not.goi...@seen.com> wrote in <hnp642$l9s$1...@speranza.aioe.org>:
I was joking!
But on a more serious note:
Most visually impaired have great sense in their fingers,
they will have no problem feeling what side of an AA of AAA goes where.
I can do it too wit heyes closed :-)
MooseFET
I tend to be designing things that are called "portable" and run from
a car
battery or the like. Right now I am doing the lowest powered product
ever
and that is 2.5W.
>
> I like diode and polyswitch, or MOSFET circuit.
I have found that polyswitches can't be trusted if you have a
significant
battery to get hooked up backwards. They take too long to go open.
I have used the MOSFET trick
I used a diode to supply power to a little circuit that pumps the gate
of the MOSFET up so that the battery voltage doesn't have to be
enough
to work the MOSFET.
>
> Grant.
E
"Grant" <o...@grrr.id.au> kirjoitti
viestissä:bhe0q5hnkemc8aluv...@4ax.com...
But you can solve that power problem with impulse relay. Connect coil thru
diode so that it gets power when polarity is wrong and another flyback diode
across coil to ensure it goes all way to another position. Then when
polarity is
wrong relay gets power and changes polarity.
Only problem is that you have to find someone how makes such relays...
schematic:
http://koti.mbnet.fi/erkkak/imp/imp.png
-ek
John Fields
>Hi All,
>Still working on my color reader, and getting close. Biggest problem
>is that now I have almost TOO much drive on my LEDs, but that I can
>deal with!
>
>Now, to the latest problem. My system is for the visually impaired. I
>just put the batteries in one of my prototypes backwards, and it
>didn't last very long. While I expect this device to have very long
>battery life, since it normally doesn't operate but for a second or
>two, it looks like the MC1253's don't like getting reversed biased
>very long. So, for my design question of the day - What is your
>favorite circuit for preventing reverse bias from the batteries? The
>old diode trick drops too much voltage, so wondered if there are any
>clever FET tricks to block backwards voltages.
---
View in courier:
If it's only on for a short time why not use a relay?
_____
+-----------------------O | O--+
| NO | |
+--O---> | | [LOAD]
|+ | | |
[BAT] O---[DIODE>]--[COIL]--+
| |
+------------------------------+
JF
Grant
Bigger diode? Where I've seen them used was on 24V traction battery,
lots heating power available.
Charlie E.
Presently looking at http://www.micrel.com/_PDF/mic94052-53.pdf which
seems to fit the bill. Any one used these, and know the gotchas?
Thanks,
Charlie
Charlie E.
<nos...@nowhere.com> wrote:
>LTC4358
Yikes! $4.50 each at digikey! ouch...
Charlie
Vladimir Vassilevsky
Charlie E. wrote:
> Presently looking at http://www.micrel.com/_PDF/mic94052-53.pdf which
> seems to fit the bill. Any one used these, and know the gotchas?
#3: If the input voltage terminals are shorted, this event is called
"psst" in language of zurgs. For the same reason, you can't make an OR
of two batteries on the load with a pair of FETs. The ESD while
inserting the bateries will do "psst" to FETs also, unless you take
precautions.
VLV
Joerg
And over $2 in production qties, which is why I never used a solution
like that and kept designing with discretes instead. LTC is a great
company but the pricing on the more mundane parts such as this one is
IMHO a wee bit out of touch.
Jim Thompson
wrote:
>On Tue, 16 Mar 2010 17:57:01 -0500, Vladimir Vassilevsky
It's a power NMOS plus a charge pump.
Gate drive requires no power in your application (slow).
Could you use discrete power MOS plus a 12V button cell? (Can't quote
the part number, CR...., but there's one in my Q45 remote)
Jazzy would be push and release button, flyback inductor powers NMOS
gate ;-)
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The only thing bipartisan in this country is hypocrisy
Jim Thompson
wrote:
If source/body orientation is as shown, it can't handle reverse
battery :-(
Ooops! Yes it will... Apply battery at terminal "D", load at terminal
"VIN"... just as I showed in...
Message-ID: <om20q55rp2gcfo182...@4ax.com>
Caution... who knows where "real" substrate is, so buy one and test
:-)
Jim Thompson
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>On Wed, 17 Mar 2010 08:42:42 -0700, Charlie E. <edmo...@ieee.org>
>wrote:
>
[snip]
>>
>>Presently looking at http://www.micrel.com/_PDF/mic94052-53.pdf which
>>seems to fit the bill. Any one used these, and know the gotchas?
>>
>>Thanks,
>>Charlie
>
>If source/body orientation is as shown, it can't handle reverse
>battery :-(
>
>Ooops! Yes it will... Apply battery at terminal "D", load at terminal
>"VIN"... just as I showed in...
>
>Message-ID: <om20q55rp2gcfo182...@4ax.com>
>
>Caution... who knows where "real" substrate is, so buy one and test
>:-)
>
> ...Jim Thompson
An additional Joerg-ian caution: Micrel's website has no E-mail
contact info, you have to call... probably get someone who doesn't
know shit :-(
D Yuniskis
Jan Panteltje wrote:
> On a sunny day (Tue, 16 Mar 2010 17:13:43 -0700) it happened D Yuniskis
> <not.goi...@seen.com> wrote in <hnp642$l9s$1...@speranza.aioe.org>:
>
>> Hi Jan,
>>
>> Jan Panteltje wrote:
>>> Use a bigger batteriy and a bridge rectifier,
>>> then it does not matter how they are put in.
>> The device ends up larger. And weighs more, etc.
>>
>> For *one* device, this is no big deal. But, folks with
>> disabilities tend to have *lots* of "special devices".
>> Each is typically larger than it's counterpart (for
>> the mainstream population).
>
> I was joking!
> But on a more serious note:
> Most visually impaired have great sense in their fingers,
> they will have no problem feeling what side of an AA of AAA goes where.
This typically depends on the cause of the vision loss.
E.g., those suffering from diabetic retinopathy will tend
to have diminished sensitivity in extremities. (i.e., Braille
is a non-starter)
Jim Thompson
wrote:
>Hi All,
>Still working on my color reader, and getting close. Biggest problem
>is that now I have almost TOO much drive on my LEDs, but that I can
>deal with!
>
>Now, to the latest problem. My system is for the visually impaired. I
>just put the batteries in one of my prototypes backwards, and it
>didn't last very long. While I expect this device to have very long
>battery life, since it normally doesn't operate but for a second or
>two, it looks like the MC1253's don't like getting reversed biased
>very long. So, for my design question of the day - What is your
>favorite circuit for preventing reverse bias from the batteries? The
>old diode trick drops too much voltage, so wondered if there are any
>clever FET tricks to block backwards voltages.
>
>Thanks!
>
>Charlie
WHAT is an MC1253? Maybe local protection?
Joerg
> On Wed, 17 Mar 2010 09:32:44 -0700, Jim Thompson
> <To-Email-Use-Th...@My-Web-Site.com> wrote:
>
>> On Wed, 17 Mar 2010 08:42:42 -0700, Charlie E. <edmo...@ieee.org>
>> wrote:
>>
> [snip]
>>> Presently looking at http://www.micrel.com/_PDF/mic94052-53.pdf which
>>> seems to fit the bill. Any one used these, and know the gotchas?
>>>
>>> Thanks,
>>> Charlie
>> If source/body orientation is as shown, it can't handle reverse
>> battery :-(
>>
>> Ooops! Yes it will... Apply battery at terminal "D", load at terminal
>> "VIN"... just as I showed in...
>>
>> Message-ID: <om20q55rp2gcfo182...@4ax.com>
>>
>> Caution... who knows where "real" substrate is, so buy one and test
>> :-)
>>
>> ...Jim Thompson
>
> An additional Joerg-ian caution: Micrel's website has no E-mail
> contact info, you have to call... probably get someone who doesn't
> know shit :-(
>
And then you have large companies where you write to a provided email
link, asking a question where it's obvious that major sales volume could
result, get no response, ask at another email address, get no response.
Recently happened at ON Semi, a manufacturer whose parts I otherwise
really like. Sad. All the while everyone laments about the economy :-(
Charlie E.
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmo...@ieee.org>
>wrote:
>
>>Hi All,
>>Still working on my color reader, and getting close. Biggest problem
>>is that now I have almost TOO much drive on my LEDs, but that I can
>>deal with!
>>
>>Now, to the latest problem. My system is for the visually impaired. I
>>just put the batteries in one of my prototypes backwards, and it
>>didn't last very long. While I expect this device to have very long
>>battery life, since it normally doesn't operate but for a second or
>>two, it looks like the MC1253's don't like getting reversed biased
>>very long. So, for my design question of the day - What is your
>>favorite circuit for preventing reverse bias from the batteries? The
>>old diode trick drops too much voltage, so wondered if there are any
>>clever FET tricks to block backwards voltages.
>>
>>Thanks!
>>
>>Charlie
>
>WHAT is an MC1253? Maybe local protection?
>
> ...Jim Thompson
It's a Microchip charge pump regulator. Using two, one to provide
3.3VDC for most of the circuit, and one to boost the LED drive to a
constant current of 20mA. Although, I am thinking of lowering that to
12mA to give more life...
Charlie
Jim Thompson
wrote:
Googling on MC1253 yields nada... You typo'd... it's MCP1253 :-)
Just put an NPN in the ground feed.
legg
>Charlie E. wrote:
<snip>
>
>
>I like LTC4358.
>
>They took care of a lot of problems typical for trivial DIY reverse
>battery protection circuits.
>
>Vladimir Vassilevsky
>DSP and Mixed Signal Design Consultant
>http://www.abvolt.com
Cowards: No V/I characteristics around zero.
Hides a potential can of worms.
..... the normally-off synchronous rectifier has been a bee in my
bonnet for a long time.
RL
dagmarg...@yahoo.com
> Hammy wrote:
> > On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmond...@ieee.org>
> > wrote:
>
> >> Hi All,
> >> Still working on my color reader, and getting close. Biggest problem
> >> is that now I have almost TOO much drive on my LEDs, but that I can
> >> deal with!
>
> >> Now, to the latest problem. My system is for the visually impaired. I
> >> just put the batteries in one of my prototypes backwards, and it
> >> didn't last very long. While I expect this device to have very long
> >> battery life, since it normally doesn't operate but for a second or
> >> two, it looks like the MC1253's don't like getting reversed biased
> >> very long. So, for my design question of the day - What is your
> >> favorite circuit for preventing reverse bias from the batteries? The
> >> old diode trick drops too much voltage, so wondered if there are any
> >> clever FET tricks to block backwards voltages.
>
> >> Thanks!
>
> >> Charlie
>
>
> That renders the unit dead and a blind or almost blind person will have
> a hard time finding or buying the proper fuse and installing it.
>
> Charlie: Solution #3 is the ticket (look on Hammy's link). But make sure
> that the FET is guaranteed to be fully turned on at the lowest allowed
> battery voltage, IOW the point where an UVLO comes on.
>
> --
> Regards, Joerg
Joerg, you big spender! Use an n-FET--they're better and cheaper--in
the ground lead.
--
Cheers,
James Arthur
Joerg
Yup, that's what I'd do in this case :-)
Jim Thompson
wrote:
Where do you get a discrete NMOSFET that will be thoroughly on at 1.8V
VGS?
The Micrel part _may_ work.
Spehro Pefhany
Here's one:
http://www.fairchildsemi.com/ds/FD%2FFDMA410NZ.pdf
50m ohm at 1.5V Vgs.
Does n-channel still offer a cost advantage over p-channel for very
low voltage devices?
Here's a p-channel device with 113m ohm at 1.2V Vgs.
http://www.vishay.com/docs/74620/sia419dj.pdf
Apparently a SC-70 can dissipate 19W if you can hold the case to
25°C...
Joerg
Plenty of others. If it has to be cheap (and somehow it always has to
be...), here's an example at around 15 cents, Rdson guaranteed down to 1.5V:
http://www.diodes.com/datasheets/ds31186.pdf
You need to get out into the world of discretes some more :-)
Jim Thompson
<spef...@interlogDOTyou.knowwhat> wrote:
>On Thu, 18 Mar 2010 10:53:31 -0700, Jim Thompson
><To-Email-Use-Th...@My-Web-Site.com> wrote:
>
>>On Thu, 18 Mar 2010 10:25:17 -0700, Joerg <inv...@invalid.invalid>
>>wrote:
>>
>>>dagmarg...@yahoo.com wrote:
[snip]
>>>>>
>>>>> Charlie: Solution #3 is the ticket (look on Hammy's link). But make sure
>>>>> that the FET is guaranteed to be fully turned on at the lowest allowed
>>>>> battery voltage, IOW the point where an UVLO comes on.
>>>>>
>>>>> --
>>>>> Regards, Joerg
>>>>
>>>> Joerg, you big spender! Use an n-FET--they're better and cheaper--in
>>>> the ground lead.
>>>>
>>>
>>>Yup, that's what I'd do in this case :-)
>>
>>Where do you get a discrete NMOSFET that will be thoroughly on at 1.8V
>>VGS?
>
>Here's one:
>http://www.fairchildsemi.com/ds/FD%2FFDMA410NZ.pdf
>
>50m ohm at 1.5V Vgs.
>
>Does n-channel still offer a cost advantage over p-channel for very
>low voltage devices?
I don't think so...
>
>Here's a p-channel device with 113m ohm at 1.2V Vgs.
>http://www.vishay.com/docs/74620/sia419dj.pdf
It appears that the N-channel part is made on an P-substrate and
vice-versa.
>
>Apparently a SC-70 can dissipate 19W if you can hold the case to
>25°C...
>
[snip]
Nice devices!
Jim Thompson
wrote:
>Jim Thompson wrote:
>> On Thu, 18 Mar 2010 10:25:17 -0700, Joerg <inv...@invalid.invalid>
>> wrote:
>>
>>> dagmarg...@yahoo.com wrote:
>>>> On Mar 16, 1:18 pm, Joerg <inva...@invalid.invalid> wrote:
>>>>> Hammy wrote:
>>>>>> On Tue, 16 Mar 2010 10:56:46 -0700, Charlie E. <edmond...@ieee.org>
>>>>>> wrote:
[snip]
>>>>>
>>>>> Charlie: Solution #3 is the ticket (look on Hammy's link). But make sure
>>>>> that the FET is guaranteed to be fully turned on at the lowest allowed
>>>>> battery voltage, IOW the point where an UVLO comes on.
>>>>>
>>>>> --
>>>>> Regards, Joerg
>>>> Joerg, you big spender! Use an n-FET--they're better and cheaper--in
>>>> the ground lead.
>>>>
>>> Yup, that's what I'd do in this case :-)
>>
>> Where do you get a discrete NMOSFET that will be thoroughly on at 1.8V
>> VGS?
>>
>> The Micrel part _may_ work.
>>
>
>Plenty of others. If it has to be cheap (and somehow it always has to
>be...), here's an example at around 15 cents, Rdson guaranteed down to 1.5V:
>
>http://www.diodes.com/datasheets/ds31186.pdf
>
>You need to get out into the world of discretes some more :-)
Nope! I avoid markets that are priced like popcorn.
Except for my own G-jobs :-)
Joerg
Oh, it's not always that way. Roughly half of my designs aren't required
to be rock-bottom in BOM cost. Although I can't help it, the calculator
in my head is always running. Sometimes clients are surprised when they
see the (working) circuit. "You mean, that's it?"
[...]
Jim Thompson
wrote:
>Jim Thompson wrote:
>> On Thu, 18 Mar 2010 11:57:26 -0700, Joerg <inv...@invalid.invalid>
>> wrote:
[snip]
>>>>
>>> Plenty of others. If it has to be cheap (and somehow it always has to
>>> be...), here's an example at around 15 cents, Rdson guaranteed down to 1.5V:
>>>
>>> http://www.diodes.com/datasheets/ds31186.pdf
>>>
>>> You need to get out into the world of discretes some more :-)
>>
>> Nope! I avoid markets that are priced like popcorn.
>>
>
>Oh, it's not always that way. Roughly half of my designs aren't required
>to be rock-bottom in BOM cost. Although I can't help it, the calculator
>in my head is always running. Sometimes clients are surprised when they
>see the (working) circuit. "You mean, that's it?"
>
>[...]
I get that all the time. I really enjoy finding clever solutions to
difficult problems. If I ever lose that capability I'll simply
self-dispatch :-)
Joerg
> On Thu, 18 Mar 2010 12:26:57 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>> Jim Thompson wrote:
>>> On Thu, 18 Mar 2010 11:57:26 -0700, Joerg <inv...@invalid.invalid>
>>> wrote:
> [snip]
>>>> Plenty of others. If it has to be cheap (and somehow it always has to
>>>> be...), here's an example at around 15 cents, Rdson guaranteed down to 1.5V:
>>>>
>>>> http://www.diodes.com/datasheets/ds31186.pdf
>>>>
>>>> You need to get out into the world of discretes some more :-)
>>> Nope! I avoid markets that are priced like popcorn.
>>>
>> Oh, it's not always that way. Roughly half of my designs aren't required
>> to be rock-bottom in BOM cost. Although I can't help it, the calculator
>> in my head is always running. Sometimes clients are surprised when they
>> see the (working) circuit. "You mean, that's it?"
>>
>> [...]
>
> I get that all the time. I really enjoy finding clever solutions to
> difficult problems. If I ever lose that capability I'll simply
> self-dispatch :-)
>
That's squarely against my religious beliefs. Life doesn't end with
Alzheimers and the like. In fact, our new canine addition (former guide
dog trainee, hopefully passes therapy dog cert after Easter) will have
one such case very soon. And already has served in that area.
Joerg
Young buck say to old buck: N-channel mostly less bucks for same bang :-)
I don't have much in examples anymore because the notes about p-channel
candidates where used to kindle the wood stove. But it happened time and
again when I thought about push-pull drivers and two n-channels plus
bootstrap was the better deal (financially).
>> Here's a p-channel device with 113m ohm at 1.2V Vgs.
>> http://www.vishay.com/docs/74620/sia419dj.pdf
>
> It appears that the N-channel part is made on an P-substrate and
> vice-versa.
>
>> Apparently a SC-70 can dissipate 19W if you can hold the case to
>> 25°C...
>>
> [snip]
>
> Nice devices!
>
> ...Jim Thompson
--
Jim Thompson
wrote:
I only believe in myself, so I have no such problem :-)
Jim Thompson
wrote:
That was true in the past. Now-a-days I see no rationale for a price
difference except for "what the market will bear" :-)
Joerg
There really is a penalty. Yeah, initially the difference may seem tiny
or zilch but if you want a P-channel with the same performance as the
N-channel and not just 70%, very different thing.
Joerg
Then you'll have a (huge) problem after you die ;-)
Jim Thompson
wrote:
I promise to not be "greasy" :-)
JosephKK
So there is going to be past passing party where there will be JT chops and
sausages and handouts of smoked JT?
Michael A. Terrell
Joerg wrote:
>
> D Yuniskis wrote:
> > Joerg wrote:
> >>> I just want something for my bugout-bag that I can rely on
> >>> *without* having to worry that some component (e.g., a
> >>> battery *buried* inside the "emergency light") has died
> >>> because it's been in storage for 10 years... I *think*
> >>> this thing will work good as there are no "components"
> >>> that I'd have to worry about crapping out (just the little
> >>> DC "motor/generator" and a bunch of mechanical bits)
> >>>
> >>> What good are emergency devices if you can't rely on
> >>> them in an emergency?? :>
> >>
> >> That's what preventive maintenance is for :-)
> >
> > Bug out bag isn't something that sits in a prominent
> > position in the house. I.e., you've got to go *looking*
> > for it. And, hopefully, *never* need it. (out of sight,
> > out of mind)
> >
>
> Ahm, what about the food items in there? Just imagine, you and your
> family have successfully evacuated. Now dad does the manly thing and
> starts the fire. Mom pulls out a can of Progresso, says 'Best before
> 1998' on there, puts in can opener ... *POOF* .. *SPLAT* ... a horrid
> stench wafts through the area ... "Oh, maybe that's why the can was
> bulging" :-)
Didn't they teach you about stock rotation in Europe? Once a year
the emergency food and batteries are replaced with fresh stock, and the
old stock is put into the regular stock.
BTW, some canned goods were found in 'Old West' ghost towns that were
about 100 years old. Other than loss of flavor, they were supposed to
still be safe to eat.
--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'
Joerg
That's exactly what I was explaining, to include batteries in the
rotating scheme.
> BTW, some canned goods were found in 'Old West' ghost towns that were
> about 100 years old. Other than loss of flavor, they were supposed to
> still be safe to eat.
>
We had some stuff like that in the army. As for flavor, that was rather
debatable even when "fresh" :-)
D Yuniskis
Joerg wrote:
> Michael A. Terrell wrote:
>> BTW, some canned goods were found in 'Old West' ghost towns that were
>> about 100 years old. Other than loss of flavor, they were supposed to
>> still be safe to eat.
>
> We had some stuff like that in the army. As for flavor, that was rather
> debatable even when "fresh" :-)
<grin> As a kid, I spent a few months living on C-rations (research).
It's hard to imagine doing that for a prolonged period. Even the
"chocolate" was abysmal!
I am surprised, though, that things *can* stay preserved, canned,
for such a long period of time. I imagine it depends on the
foodstuffs involved, the materials from which the cans are made,
any *coatings* applied to the insides of the cans and the
mechanical integrity of those cans.
I would imagine vacuum packing something like beans in glass
(or metal) would also have a very long shelf life -- but I'm
not a big fan of legumes! :-(
Charlie E.
I had a similiar experience. Visiting a friend, I noticed a bunch of
boxes of C-rations sitting in the garage. Asked about them, and found
they were expired rations from a fallout shelter. I asked if I could
have some, and soon found myself in possession of about six cases of
them. Over the next few months, tried them out, and found which were
tolerable, and which were really, really bad! A couple of years
later, at ROTC summer camp, when we were issued C-rations, I knew
which ones to get, and which ones to trade... ;-)
Charlie
Michael A. Terrell
"Charlie E." wrote:
>
> I had a similiar experience. Visiting a friend, I noticed a bunch of
> boxes of C-rations sitting in the garage. Asked about them, and found
> they were expired rations from a fallout shelter. I asked if I could
> have some, and soon found myself in possession of about six cases of
> them. Over the next few months, tried them out, and found which were
> tolerable, and which were really, really bad! A couple of years
> later, at ROTC summer camp, when we were issued C-rations, I knew
> which ones to get, and which ones to trade... ;-)
Some of the ones I got while in the Army were over 20 years old. When
its -20 to -30 degrees and the only food for 15 miles, you don't
complain, if you want your next meal.
Michael A. Terrell
It wasn't intened to be 'good', it was meant to keep you alive.
Michael A. Terrell
Glass is excellent for canning, till the rubber seal rots.
Joel Koltner
"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:4BA95EC8...@earthlink.net...
> Some of the ones I got while in the Army were over 20 years old. When
> its -20 to -30 degrees and the only food for 15 miles, you don't
> complain, if you want your next meal.
Where were you stationed, if you don't mind my asking?
---Joel
D Yuniskis
Ah, I wasn't as lucky. That's *all* I had to eat! :-/
(though I could have "as much as I wanted" -- small consolation
that! :> )
> tolerable, and which were really, really bad! A couple of years
I think the franks and beans were tolerable (and I *hate* beans -- so
that tells you how bad I considered most of it!). The pasta (?)
defied description. :< The little "fruit cakes" doubled as
hockey pucks :-/
> later, at ROTC summer camp, when we were issued C-rations, I knew
> which ones to get, and which ones to trade... ;-)
Ones to trade: ALL
Ones to get: see above
;-)
But, remember to save the TP packet! (and the P38, of course!!)
Joerg
> Joerg wrote:
[...]
>>> BTW, some canned goods were found in 'Old West' ghost towns that were
>>> about 100 years old. Other than loss of flavor, they were supposed to
>>> still be safe to eat.
>>>
>> We had some stuff like that in the army. As for flavor, that was rather
>> debatable even when "fresh" :-)
>
>
> It wasn't intened to be 'good', it was meant to keep you alive.
>
Well, we sometimes had helpful friends around to kill the stale taste.
What were their names .... oh yeah, now I remember. Jack Daniels, Jim
Beam ...
Michael A. Terrell
Fort Greely, Alaska
Michael A. Terrell
Joerg wrote:
>
> Michael A. Terrell wrote:
> > Joerg wrote:
> >> Michael A. Terrell wrote:
>
> [...]
>
> >>> BTW, some canned goods were found in 'Old West' ghost towns that were
> >>> about 100 years old. Other than loss of flavor, they were supposed to
> >>> still be safe to eat.
> >>>
> >> We had some stuff like that in the army. As for flavor, that was rather
> >> debatable even when "fresh" :-)
> >
> >
> > It wasn't intened to be 'good', it was meant to keep you alive.
> >
>
> Well, we sometimes had helpful friends around to kill the stale taste.
> What were their names .... oh yeah, now I remember. Jack Daniels, Jim
> Beam ...
Alcohol is a painful way to die, in sub zero temperatures.
JosephKK
Most often the things that matter are cleanliness of the containers and
the sterility after closing. After the previous coatings and pH of the
preserved food play.
Martin Brown
> Hi Joerg,
>
> Joerg wrote:
>> Michael A. Terrell wrote:
>>> BTW, some canned goods were found in 'Old West' ghost towns that were
>>> about 100 years old. Other than loss of flavor, they were supposed to
>>> still be safe to eat.
>>
>> We had some stuff like that in the army. As for flavor, that was
>> rather debatable even when "fresh" :-)
>
> <grin> As a kid, I spent a few months living on C-rations (research).
> It's hard to imagine doing that for a prolonged period. Even the
> "chocolate" was abysmal!
Do you really mean that or do you mean it actually tasted of *real*
chocolate instead of Hershey bars brown sugary rancid fat product.
ISTR chocolate and boiled sweets tins were about the best surviving of
the timed out rations. And even though UK rations are nothing to write
home about the tinned stuff was OK long after its official junk by day.
>
> I am surprised, though, that things *can* stay preserved, canned,
> for such a long period of time. I imagine it depends on the
> foodstuffs involved, the materials from which the cans are made,
> any *coatings* applied to the insides of the cans and the
> mechanical integrity of those cans.
Keep the air out and make sure they are sterile to begin with and they
will last without bacterial decay until the seal is broken. US army
reckons nearly 50 years. The contents may degrade somewhat though in
terms of texture and taste. The infamous tinned meat Spam seemed to last
pretty well without changing at all long after the expiry date.
> I would imagine vacuum packing something like beans in glass
> (or metal) would also have a very long shelf life -- but I'm
> not a big fan of legumes! :-(
Some goods tinned for early Antarctic expeditions still exist and are
nominally edible.
Regards,
Martin Brown
Joerg
> Joerg wrote:
>> Michael A. Terrell wrote:
>>> Joerg wrote:
>>>> Michael A. Terrell wrote:
>> [...]
>>
>>>>> BTW, some canned goods were found in 'Old West' ghost towns that were
>>>>> about 100 years old. Other than loss of flavor, they were supposed to
>>>>> still be safe to eat.
>>>>>
>>>> We had some stuff like that in the army. As for flavor, that was rather
>>>> debatable even when "fresh" :-)
>>>
>>> It wasn't intened to be 'good', it was meant to keep you alive.
>>>
>> Well, we sometimes had helpful friends around to kill the stale taste.
>> What were their names .... oh yeah, now I remember. Jack Daniels, Jim
>> Beam ...
>
>
> Alcohol is a painful way to die, in sub zero temperatures.
>
Well, we didn't empty the whole bottle :-)
Michael A. Terrell
Joerg wrote:
>
> Michael A. Terrell wrote:
> > Joerg wrote:
> >> Michael A. Terrell wrote:
> >>> Joerg wrote:
> >>>> Michael A. Terrell wrote:
> >> [...]
> >>
> >>>>> BTW, some canned goods were found in 'Old West' ghost towns that were
> >>>>> about 100 years old. Other than loss of flavor, they were supposed to
> >>>>> still be safe to eat.
> >>>>>
> >>>> We had some stuff like that in the army. As for flavor, that was rather
> >>>> debatable even when "fresh" :-)
> >>>
> >>> It wasn't intened to be 'good', it was meant to keep you alive.
> >>>
> >> Well, we sometimes had helpful friends around to kill the stale taste.
> >> What were their names .... oh yeah, now I remember. Jack Daniels, Jim
> >> Beam ...
> >
> >
> > Alcohol is a painful way to die, in sub zero temperatures.
> >
>
> Well, we didn't empty the whole bottle :-)
All it takes is one big gulp to kill you. It can freeze the contents
of your stomach and cause a painful death.
That was one of the things they stressed during our survival
training. One moron interrupted the training right after it started
with the statement, "I don't have to worry about freezing, cause I'll be
full of antifreeze". They he threw a hissy fit when the instructor
stated that people with black skin would freeze faster that someone with
white skin and called him a racist. The moron wouldn't believe it had
to do with black body radiation, and the fact that the instructor had
almost black skin. The worst thing was that I had to work with that
drunken idiot for a year. He was SUPPOSED to be a broadcast engineer,
but couldn't make the simplest repairs. He couldn't run the boards, do
camera work or anything else in the studio or control room, so they
stuck him in the film library, and he couldn't even do that right.
Michael A. Terrell
Fred Abse wrote:
>
> On Tue, 23 Mar 2010 20:37:28 -0400, Michael A. Terrell wrote:
>
> > Some of the ones I got while in the Army were over 20 years old. When
> > its -20 to -30 degrees and the only food for 15 miles, you don't
> > complain, if you want your next meal.
>
have you ever tried to dig a latrine in frozen tundra? We had to put
a ground rod through it, which required an oxyacetylene torch to hit the
tip, so the rod didn't bend. Heat it red hot, drive it a few inches,
pull it out and repeat. It took all day and used most of the full tanks
of Oxygen and Acetylene.