Re: [EE] Radio Light Switch
Oli Glaser
friend, but he insists on paying me, so would like to make them as good as
possible)
Basically, the setup is 6 lights that need to be switched in/out of circuit,
so one TX and 6 RXs needed.
The switching circuit is no problem, but I'm not an expert on the RF side of
things, so was looking at rfPICs and zigbee, neither of which I have used
before. Any advice from anyone on this front before I start spending would
be most appreciated.
--
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View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Dario Greggio
> I have been asked to design a radio light switch (just a one off for a
> friend, but he insists on paying me, so would like to make them as good as
> possible)
> Basically, the setup is 6 lights that need to be switched in/out of circuit,
> so one TX and 6 RXs needed.
I just finished a "lightweight" app with MRF24J40 in "custom" protocol,
and USB interface.
Basically a send/receive of packets: would fit your job easily.
--
Ciao, Dario
--
Cyberdyne
Sean Breheny
very good results.
Sean
Michael Watterson
> I have been asked to design a radio light switch (just a one off for a
> friend, but he insists on paying me, so would like to make them as good as
> possible)
> Basically, the setup is 6 lights that need to be switched in/out of circuit,
> so one TX and 6 RXs needed.
>
> The switching circuit is no problem, but I'm not an expert on the RF side of
> things, so was looking at rfPICs and zigbee, neither of which I have used
> before. Any advice from anyone on this front before I start spending would
> be most appreciated.
>
>
>
I have purchased 433.92MHz superhet from here. Neat design with image
reject mixer and no external IF filter. Works well
The TX is a 433.92MHz SAW and transistor colpitts/clapp (or buy their
module)
http://stores.shop.ebay.ie/e-MadeinCHN__W0QQ_armrsZ1
http://www.rfremotech.com/SomeProducts.html
They seem to make the stuff.
They have FCC and CE modules and stuff that doesn't look like it could
possibly be either.
See also Maxim and Analog Devices app notes. But at your volume level
the off the shelf module are the solution.
Oli Glaser
Seems like a module of some sort may be the way to go, and a simple custom
protocol may be better than messing around with stuff like Zigbee for an app
like this. The MRF24J40MA module looks quite good, and is pretty cheap at
$9. The xBee stuff and the little superhet look useful too. I didn't notice
at first that the rfPICs only have TX capability, and although this would be
usable, I would prefer some basic feedback from the switches. I will do some
research on all the options mentioned and see what suits best. About time I
got better acquainted with RF networking in general anyway.
Dr Skip
I'm helping a family 'in need' repair a gas range, and it uses an
electronic ignition module (schematic copied below). It is no longer
available, and the transformer secondary is open. The neon light
flashes, so assuming electronics are fine, but I haven't probed for
other problems, so at a minimum, I need to replace T1. Does anyone have
any practical, simple, and cheap suggestions for a one-off HV
transformer? Size is important (1 inch sq is original size, but I can
make a little more room).
If winding one is easy enough, with readily available components, that
would be fine, just need some experienced pointers. Would prefer
scrounging from another application where I can just replace with a
similar transformer, or wire it externally, so whomever plays with these
kinds of igniters in their hobby might know where they can be found.
This is 120v AC in.
TIA -Skip
C1 A D1 T1 o
H o----||----------------+-------|>|-------+-------+ +-----o HVP+
.1 uF D2 1N4007 | 1N4007 | | o ||(
250 V +----|>|----+ | +--+ ||(
| | | )||(
+---/\/\----+ | #20 )||( 1:35
| R1 1M | C2 _|_ )||(
| R2 / 1 uF --- +--+ ||(
| 18M \ DL1 400 V | __|__ ||(
| / NE-2 | _\_/_ +-----o HVP-
| | +--+ | / |
| +----|oo|----+---------' | SCR1
| C3 | +--+ | | | S316A
| .047 uF _|_ R3 / | | 400 V
| 250 V --- 180 \ | | 1 A
| | / | |
R4 2.7K | | | | |
N o---/\/\---+-----------+------------+----+-------+
Steve Smith
or scavenge an olde laser printer for the electrostatic generation
transformer that might be a good bet...
Steve
Michael Watterson
> Greetings,
>
> I'm helping a family 'in need' repair a gas range, and it uses an
> electronic ignition module (schematic copied below). It is no longer
> available, and the transformer secondary is open. The neon light
> flashes, so assuming electronics are fine, but I haven't probed for
> other problems, so at a minimum, I need to replace T1. Does anyone have
> any practical, simple, and cheap suggestions for a one-off HV
> transformer? Size is important (1 inch sq is original size, but I can
> make a little more room).
>
want a 120V to 12V Wall-wart to power it, though the later is bigger.
The cheap cattle fences appear to actually be a circuit very like that
off 6V or 12V and using an actual car ignition coil.
That schematic barely electronics :) What stops it sparking? or is the
"H" wire switched by an opto sensor like an oil burner uses? I've seen
old oil boilers with a relay or two and CDS cell and just a very big
transformer for the spark!
Olin Lathrop
> but I'm not an expert on the RF
> side of things, so was looking at rfPICs and zigbee, neither of which
> I have used before. Any advice from anyone on this front before I
> start spending would be most appreciated.
rfPICs are very low level, and Zigbee comes with a lot of baggage. Since
this is for a one off, I would either use some simple modules or integrated
chips that some of the encoding/decoding for you.
********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014. Gold level PIC consultants since 2000.
Michael Watterson
>
>
>
> C1 A D1 T1 o
> H o----||----------------+-------|>|-------+-------+ +-----o HVP+
> .1 uF D2 1N4007 | 1N4007 | | o ||(
> 250 V +----|>|----+ | +--+ ||(
> | | | )||(
> +---/\/\----+ | #20 )||( 1:35
> | R1 1M | C2 _|_ )||(
> | R2 / 1 uF --- +--+ ||(
> | 18M \ DL1 400 V | __|__ ||(
> | / NE-2 | _\_/_ +-----o HVP-
> | | +--+ | / |
> | +----|oo|----+---------' | SCR1
> | C3 | +--+ | | | S316A
> | .047 uF _|_ R3 / | | 400 V
> | 250 V --- 180 \ | | 1 A
> | | / | |
> R4 2.7K | | | | |
> N o---/\/\---+-----------+------------+----+-------+
>
http://www.splatco.com/skb/skbredir.htm?toc.htm?2784.htm
or just a text editor/email compose?
Curious as it's prettier than usual :-)
--
Mike
Olin Lathrop
> Curious as it's prettier than usual :-)
Only if your usual is drawing circuits with ASCII art. At least this one
was fairly understandable. Looks like a lot more work for less result than
software meant for the purpose.
********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014. Gold level PIC consultants since 2000.
Richard Prosser
> Oli Glaser wrote:
>> but I'm not an expert on the RF
>> side of things, so was looking at rfPICs and zigbee, neither of which
>> I have used before. Any advice from anyone on this front before I
>> start spending would be most appreciated.
>
A quick way might also be along these lines - yuo'd need 3 kits though.
<http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4291>
RP
Oli Glaser
><http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4291>
Thanks for the suggestion - would certainly be quick, but 3 kits would cost
over $350, and I'm attempting to make it as cheap as possible, to make the
work worthwhile compared to some commercial solution. Plus they have to be
easily/cheaply fixable if anything ever breaks, and he *may* be interested
in using them for other switching purposes in the future, so once I have the
basic design sorted I could just throw together a few more for him.
Sean Breheny
Zigbee can be run in a simple peer to peer mode where they act just
like an error-corrected virtual serial connection. The XBee modules
from Digi International are one such example.
Sean
Dario Greggio
> Zigbee per-se comes with a lot of baggage, but some of the modules for
> Zigbee can be run in a simple peer to peer mode where they act just
> like an error-corrected virtual serial connection. The XBee modules
> from Digi International are one such example.
yeah, this is what I meant too.
P2P with the MRF is rather easy.
--
Ciao, Dario
--
Cyberdyne
Oli Glaser
--------------------------------------------------
From: "Olin Lathrop" <olin_p...@embedinc.com>
Sent: Sunday, June 13, 2010 8:51 PM
To: "Microcontroller discussion list - Public." <pic...@mit.edu>
Subject: Re: [EE] Radio Light Switch
> Oli Glaser wrote:
>> but I'm not an expert on the RF
>> side of things, so was looking at rfPICs and zigbee, neither of which
>> I have used before. Any advice from anyone on this front before I
>> start spending would be most appreciated.
>
> rfPICs are very low level, and Zigbee comes with a lot of baggage. Since
> this is for a one off, I would either use some simple modules or
> integrated
> chips that some of the encoding/decoding for you.
I agree, from a quick look at Zigbee, although I wouldn't mind getting to
grips with it at some point, for this project it would be far too much
messing about. A module that deals with the basics looks like the quickest
most painless way of doing this, if not quite the cheapest maybe. If it was
just one switch it could be a lot more simple(no data on carrier, just OOK
driven flip flop or something), but some sort of networking is needed here I
think.
William "Chops" Westfield
>> repair a gas range, and it uses an electronic ignition module
>> (schematic copied below). It is no longer available
Have you checked eBay? There seems to be a fair collection of
appliance stores (or something) making a sideline of selling
individual parts to the general public. In any case, similar modules
are still in common use, and anything with a similar input voltage is
very likely to contain a similar transformer...
http://stores.ebay.com/oceanwaves7__W0QQ_sacatZoceanwaves7QQ_sidZ26205610?_nkw=spark&submit=Search
(key phrase seems to be "spark module")
BillW
Oli Glaser
--------------------------------------------------
From: "Sean Breheny" <sh...@cornell.edu>
Sent: Sunday, June 13, 2010 10:09 PM
To: "Microcontroller discussion list - Public." <pic...@mit.edu>
Subject: Re: [EE] Radio Light Switch
> Zigbee per-se comes with a lot of baggage, but some of the modules for
> Zigbee can be run in a simple peer to peer mode where they act just
> like an error-corrected virtual serial connection. The XBee modules
> from Digi International are one such example.
That's the kind of thing I'm looking for - an RF version of an SPI or I2C
network. At £20 (from RS) so £140 for 7 they are right at the top of my
preferred price range though. Ideally I was *hoping* for something under £10
for the RF stuff.
Michael Watterson
>> A quick way might also be along these lines - yuo'd need 3 kits though.
>>
>
>
>> <http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4291>
>>
>
> Thanks for the suggestion - would certainly be quick, but 3 kits would cost
> over $350, and I'm attempting to make it as cheap as possible, to make the
> work worthwhile compared to some commercial solution. Plus they have to be
> easily/cheaply fixable if anything ever breaks, and he *may* be interested
> in using them for other switching purposes in the future, so once I have the
> basic design sorted I could just throw together a few more for him.
>
>
>
very simple 1 wire serial interface from PIC to TX and one wire RX
interface to PIC, 1200bps and simple SW.
link in my earlier post.
Michael Watterson
> --------------------------------------------------
> From: "Olin Lathrop" <olin_p...@embedinc.com>
> Sent: Sunday, June 13, 2010 8:51 PM
> To: "Microcontroller discussion list - Public." <pic...@mit.edu>
> Subject: Re: [EE] Radio Light Switch
>
>
>> Oli Glaser wrote:
>>
>>> but I'm not an expert on the RF
>>> side of things, so was looking at rfPICs and zigbee, neither of which
>>> I have used before. Any advice from anyone on this front before I
>>> start spending would be most appreciated.
>>>
>> rfPICs are very low level, and Zigbee comes with a lot of baggage. Since
>> this is for a one off, I would either use some simple modules or
>> integrated
>> chips that some of the encoding/decoding for you.
>>
>
> I agree, from a quick look at Zigbee, although I wouldn't mind getting to
> grips with it at some point, for this project it would be far too much
> messing about. A module that deals with the basics looks like the quickest
> most painless way of doing this, if not quite the cheapest maybe. If it was
> just one switch it could be a lot more simple(no data on carrier, just OOK
> driven flip flop or something), but some sort of networking is needed here I
> think.
>
>
Preamble bits to initialise dataslicer on OOK
N bit address
K bit command
C bits CRC
(stops TV wireless adaptors miss-operating it)
Manchester encoded/decoder.
Either set address on receiver via DIP switch or via IRLED (on TX unit)
and IR RX or Phototransistor of rotten gain so you have to hold it <
inches away to set switch address.
The OOK/ASK TX is lower power than IR remote for 20m range.
ZigBee is a complex solution looking for a problem.
Michael Watterson
> --------------------------------------------------
> From: "Sean Breheny" <sh...@cornell.edu>
> Sent: Sunday, June 13, 2010 10:09 PM
> To: "Microcontroller discussion list - Public." <pic...@mit.edu>
> Subject: Re: [EE] Radio Light Switch
>
>
>> Zigbee per-se comes with a lot of baggage, but some of the modules for
>> Zigbee can be run in a simple peer to peer mode where they act just
>> like an error-corrected virtual serial connection. The XBee modules
>> from Digi International are one such example.
>>
>
> That's the kind of thing I'm looking for - an RF version of an SPI or I2C
> network. At £20 (from RS) so £140 for 7 they are right at the top of my
> preferred price range though. Ideally I was *hoping* for something under £10
> for the RF stuff.
>
>
>
http://cgi.ebay.ie/RF-Wireless-Radio-Superheterodyne-Receiver-Module-RM1SH-/290442806879
They do sell "buy it now" or direct
See http://www.rfremotech.com/ReceiverModules.html
You can either buy module with decoder already, or just TX & RX for 1
wire serial. The modules I got very well made and under €5 each for
receivers.
I used the TX part of an €8 wirless Door bell and compared it with home
made SAW + transistor TX and also TX from return part of video sender.
I compared the RX with Super Regen and also superhet RX from 433MHz
reverse link of 2.4GHz video senders. The RX is very good, but I had to
add the short on pads on PCB to enable Digital Squelch (left open by
default).
cdb
GBP7.00 at the moment ex - GST/VAT etc.
Parallax have some ready made modules as does Futurlec for US$14.90 each,
they also have wireless datalink modules for US$6.90 - normal caveat of
long time wait with Futurelec products applies. :)
Colin
--
cdb, co...@btech-online.co.uk on 14/06/2010
Web presence: www.btech-online.co.uk
Hosted by: www.1and1.co.uk/?k_id=7988359
Oli Glaser
--------------------------------------------------
From: "Michael Watterson" <mi...@radioway.org>
Sent: Sunday, June 13, 2010 10:53 PM
Thanks, this all sounds pretty sensible too, some nice little modules there.
I think I'll grab a couple to experiment with. By the way - what about the
superregen ones? they are about half the price of the superhet.
Olin Lathrop
> If it was just one switch it could be a lot more
> simple(no data on carrier, just OOK driven flip flop or something),
> but some sort of networking is needed here I think.
Not encoding data on the carrier would be a bad idea even with a single
switch. However, you don't need much more than that, and I don't see where
the networking comes in.
As I understand it, you just want to turn a few lights on or off. Give each
light a ID. Each message contains the ID, the on or off command, and a
checksum. Send each command a few times for better probability it will get
there. There's a human in the loop, so if he hits the button to turn on the
light and it doesn't, he'll just hit it again.
This is a lot like your TV remote, except those usually work on IR instead
of RF. Most of the time they work, but when they don't you just hit the
button again. It's all one way communication.
For that matter, why not use IR? Does the user really need to turn lights
on and off in other rooms with entrances around a corner?
********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014. Gold level PIC consultants since 2000.
YES NOPE9
> On Jun 13, 2010, at 10:12 AM, Oli Glaser wrote:
>
> I have been asked to design a radio light switch (just a one off for a
> friend, but he insists on paying me, so would like to make them as
> good as
> possible)
> Basically, the setup is 6 lights that need to be switched in/out of
> circuit,
> so one TX and 6 RXs needed.
>
> The switching circuit is no problem, but I'm not an expert on the RF
> side of
> things, so was looking at rfPICs and zigbee, neither of which I have
> used
> before. Any advice from anyone on this front before I start spending
> would
> be most appreciated.
Did you look at
X10 modules
Insteon modules
Z-wave modules
http://www.thehomeautomationstore.com
jim
Check the January 2010 issue of Everyday Practical Electronics (EPE)
magazine.
There is a mains based project in there that might give you some leads or
Inspiration.
Regards,
Jim
-----Original Message-----
From: piclist...@mit.edu [mailto:piclist...@mit.edu] On Behalf Of
Oli Glaser
--------------------------------------------------
From: "Olin Lathrop" <olin_p...@embedinc.com>
Sent: Sunday, June 13, 2010 11:55 PM
To: "Microcontroller discussion list - Public." <pic...@mit.edu>
Subject: Re: [EE] Radio Light Switch
> Oli Glaser wrote:
>> If it was just one switch it could be a lot more
>> simple(no data on carrier, just OOK driven flip flop or something),
>> but some sort of networking is needed here I think.
>
> Not encoding data on the carrier would be a bad idea even with a single
> switch. However, you don't need much more than that, and I don't see
> where
> the networking comes in.
>
> As I understand it, you just want to turn a few lights on or off. Give
> each
> light a ID. Each message contains the ID, the on or off command, and a
> checksum. Send each command a few times for better probability it will
> get
> there. There's a human in the loop, so if he hits the button to turn on
> the
> light and it doesn't, he'll just hit it again.
>
> This is a lot like your TV remote, except those usually work on IR instead
> of RF. Most of the time they work, but when they don't you just hit the
> button again. It's all one way communication.
>
> For that matter, why not use IR? Does the user really need to turn lights
> on and off in other rooms with entrances around a corner?
I agree no encoding is generally a bad idea and "networking" was the wrong
term. I meant simple IDing really, with maybe some state feedback if using
transceivers. At the moment the plan is indeed just to turn a few lights on
and off so that's what I should stick to really, but there was talk of
applying the switch to other uses, so a little more "intelligence" for
adaption purposes in future *may* be useful, but certainly not essential and
not worth a lot of extra hassle/cost.
IR would probably work fine in the current setup, but the RXs have to be
invisible, so even a small detector being visible may be a problem, plus
there is a possibility it will get used for none line of sight stuff in the
future. I will mention it though and see what he thinks. In any case, I have
the components to build a couple of IR test boards to get going with now,
and could always switch these over to RF later.
ivp
> transformer? Size is important (1 inch sq is original size, but I can
> make a little more room).
Skip, recently I made a propane igniter from a fly swatter. What ?
Yes, it's a high voltage grid made in the form of a small tennis racket
with horizontal and vertical wires coming from the two terminals of
a transformer respectively. The bug is the short between the two.
Works just like the industrial bug zappers with the UV light. As
bought new, for $3 at a surplus store, it runs on 2 x AA but I use
3 and it will make a 10mm spark between needles or a big fat one
in a spark plug
Google for bug bat
This is very similar to the one I deconstructed
http://www.gizmag.com/the-bug-bat--high-tech-insect-terminator-tennis-racket/9306/
All the original, very simple, electronics, including the transformer, fit
in the handle. Unlike a piezo starter, the spark continues for as long as
the button is presssed
A viable DIY alternative if you can't find a replacement transformer
Joe
Ruben Jönsson
> GBP7.00 at the moment ex - GST/VAT etc.
>
Yes, and although this is a zigbee module (including antenna and approval) it
can be run in som other, simpler, protocol modes. The module is actually a 2.4
GHz IEEE 802.15.4 on which the zigbee protocol is built.
Download the sample C code from microchip, attach the module to an SPI port and
some GPIOs on a PIC 18 or 24, configure the sample code with some #define's and
you're ready to go.
/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ru...@pp.sbbs.se
==============================
Michael Watterson
>
>
>>
>> Either set address on receiver via DIP switch or via IRLED (on TX unit)
>> and IR RX or Phototransistor of rotten gain so you have to hold it <
>> inches away to set switch address.
>>
>> The OOK/ASK TX is lower power than IR remote for 20m range.
>>
>
> Thanks, this all sounds pretty sensible too, some nice little modules there.
> I think I'll grab a couple to experiment with. By the way - what about the
> superregen ones? they are about half the price of the superhet.
>
>
>
* Acts as low power transmitter 24x7 so makes system SNR for all other
433MHz & 866MHz poorer
* Difficult to squelch
* Poor immunity to out of band signals
I have built Superregen "FM radio" receiver in matchbox and used
ex-equipment 433MHz Super Regen from Video senders. A Nasty 1930s
technology that refuses to die, because it's cheap. :-)
alan.b...@stfc.ac.uk
> electronic ignition module (schematic copied below). It is no longer
> available, and the transformer secondary is open. The neon light
> flashes, so assuming electronics are fine, but I haven't probed for
> other problems, so at a minimum, I need to replace T1. Does anyone
have
> any practical, simple, and cheap suggestions for a one-off HV
> transformer? Size is important (1 inch sq is original size, but I can
> make a little more room).
I would carefully check the transformer where the wires come out of the
winding. Often the wire is under tension when soldered to the connection
point, and over a period of time breaks under tension. It may be
possible to get at the broken end (can be rather difficult if the inner
end) and resolder it.
--
Scanned by iCritical.
Dr Skip
I've asked around for maybe a lawnmower engine coil, (size=small) but
get curious looks. Seems they don't use them any more. If anyone knows
what to ask for along those lines....
If I can't get the others to work, I'll move on to the electric fence
parts. In order to keep parts count and size down, do those experienced
with such think a dropping resistor would be enough to use a 12v or 6v
part on 120v?
And thanks for not blasting me about the schematic. I copied it from
someone else's labor, and pasted it explicitly using fixed width font so
as to preserve spacing. I'll have to look at that link though. ;) It's
possible individual mail readers override the font, but I tried... ;)
Thanks again,
Skip
Ruben Jönsson
>
> I've asked around for maybe a lawnmower engine coil, (size=small) but
> get curious looks. Seems they don't use them any more. If anyone knows
> what to ask for along those lines....
>
We use an ignition coil originally manufactured for a chainsaw in some of our
products. In some other (very old) products we use a coil for a car - the type
that is split up to every sparkplug through a distributor. In modern cars there
ususally is one coil per plug (or maby one per two plugs) and those can get
pretty small.
> If I can't get the others to work, I'll move on to the electric fence
> parts. In order to keep parts count and size down, do those experienced
> with such think a dropping resistor would be enough to use a 12v or 6v
> part on 120v?
>
In our old products that use ignition coils (for cars and chainsaws), we
discharge a 10uF capacitor charged to around 350V through the low voltage side
of the coil every 6th ms or so (I think you do roughly the same if I remember
your schematics correctly) and we almost never have any problems with the
coils. However, we make ionizers for the purpose of removing electrostatic
charges and the equipment should normally not produce a spark. We actually did
make a gas ignition system based on the same parts once but that never went
into production.
One thing to look out for when using ignition coils for engines is that the
primary and secondary of the ignition coil is usually connected together at one
end inside the coil and it may become a problem if the primary side is driven
with a low-side switch. The old car coils could be opened and separated but
then they have to be encapsulated (potted) again.
/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ru...@pp.sbbs.se
==============================
--
Oli Glaser
will grab some of the superhet modules Michael mentioned, also gonna grab a
couple of the MC zigbee modules too (at the very least for general learning
purposes and in case a more complex version is needed later - already been
talk of a remote temperature monitor for greenhouse that sends temp back to
PC for graphing and triggers a servo to open a window - slightly different
beast which may appear in different thread at some point :-) ). Commencing
the test IR circuit Olin mentioned today while waiting for RF stuff, and
hopefully I'll have a working model in the next few days, time and other
projects permitting.
Vitaliy
>I have been asked to design a radio light switch (just a one off for a
> friend, but he insists on paying me, so would like to make them as good as
> possible)
> Basically, the setup is 6 lights that need to be switched in/out of
> circuit,
> so one TX and 6 RXs needed.
>
> things, so was looking at rfPICs and zigbee, neither of which I have used
> before. Any advice from anyone on this front before I start spending would
> be most appreciated.
Did anybody suggest Linx modules? Cheap, reliable, easy to use.
Vitaliy
Dr Skip
On 6/15/2010 2:16 AM, Ruben Jönsson wrote:
>
> We use an ignition coil originally manufactured for a chainsaw in some of our
> products. In some other (very old) products we use a coil for a car - the type
> that is split up to every sparkplug through a distributor. In modern cars there
> ususally is one coil per plug (or maby one per two plugs) and those can get
> pretty small.
>
>
>
Barry Gershenfeld
overloaded power transformers. If they overheat, it's the run of wire to
the terminal that melts because the rest of the wire is a big thermal mass.
In a more general sense, I always do a post mortem on the bad part to see if
I can spot the problem. Many times I was able to fix it. Even if not for
re-use, but at least to prove that was the problem.
As to the schematic, sure the font got messed with, but I learned long ago
to paste it into a fixed width editor. As stated elsewhere, nice job!