Converting 7v DC to 7v AC at 50-60Hz
stigan...@gmail.com
I have hacked a clockradio and i need to supply it with power from a
12v battery. How do i invert DC to AC?
stigan...@gmail.com
Btw. the radio had a transformer 220v AC > 7v AC the datasheet can be
found at:http://www.paulanders.com/G5-LED/ver1/datablad.pdf
I would really appreciate any good suggestions on where to find a
schematic for this circuit
John Fields
---
When you say "the radio had a transformer..." does that mean you removed
it?
JF
mrda...@gmail.com
Hacked as in you don't mind it not working anymore if you continue?
What's the AC for?
Why not just put +12V on pin 20, and ground on pin 15?
Just my $0.02. Which ain't worth much... finance.yahoo.com
Michael
Michael Black
You don't.
You run it off batteries, and then build up a crystal oscillator
and divider chain to send pulses to the actual clock that it will count
and use to keep time.
You don't need AC to run the clock, after all the existing power supply
is there to convert AC to the DC that the clock needs. You do need
a source of 60Hz pulses so the clock has something to count, the AC
line usually being used for that purpose.
So you look at the clock IC, the large one, and try to find a datasheet
or at least pinout for the IC. Then from there, you can figure out
where the DC goes to power the IC, and where it gets a sample of the
AC line to "clock" the clock. That point will need to be connected
to a source of pulses at the line frequency (which I guess may
be 50Hz if you are talking about 240v AC line.
This sort of thing was common decades ago, when digital clock building
was a big wave. Now, clocks have become so cheap nobody really does
it.
You need to rethink your problem, or at least restate your problem.
There has to be a reason for you wanting to run this off a battery,
explain that and a solution is easier to derive. I'm assuming you
want it for the clock, and not the radio, but that's an assumption.
Some clock radios have a 9v battery to keep it going when the
power goes off, though I've never had one to know if they actually
keep the clock ticking away, or just supply power so the current
time isn't lost in a temporary power loss. If they keep ticking,
then that's likely a better choice for your project, since you
no longer need to supply the pulses for the clock IC. Then it
would just be a matter of applying DC voltage from the battery
to where the rectifier from the AC transformer hits the filter
capacitor.
But, if it's the clock you need, then maybe find an alternative.
I bought an LCD clock a decade ago for about five dollars, and when
the button battery died, I wired in an AA battery, and it just
runs forever. No alarm feature though. But more expensive
LCD clocks do have an alarm feature, and with some work one
could use that to turn something else on, if that's the point
of this project.
I bought an "atomic clock" at a garage sale this spring for all
of 2.00, so one has to have a good reason for modifying a clock
radio for battery operation in order to make it worth doing
the work.
Michael
Jasen Betts
you have an LM8560 (or similar) based digital alarm clock and need a
two-phase precise-frequency AC to drive the display and timer ?
As I understand it those chips don't actually need the negative part
of the AC (which makes your life easier) but they do need the
frequency to be right (or they keep time very poorly)
MM5369 is a chip that can make the right frequency for you then you
just need to feed the output to some transistors to provide an
inverted signal and boost the current so it can drive your display
Bye.
Jasen
Michael A. Terrell
The MM5369 has been obsolete for so long (20 years?) that National
Semiconductor doesn't even list it as obsolete. Also, there were
special versions like 100 Hz so if you find old stock, or surplus it may
not be 60 Hz. Even companies like Jameco don't list the MM5369 any
more.
A better choice would be a crystal & divider chain, but keep in mind
that some clock chips wand a 50% duty cucle at 60 Hz. Digikey has a lot
of suitable crystals. Fo instance, they have 60 kHz crystals starting
at 72 cebts. Divide by 1000 and yo have 60 Hz.
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stigan...@gmail.com
Thanks for all the great info!
Achually my plan is as follows: Use the display of the clockradio for
my arduino, showing values. The advantage is that the clockradio only
will take up 3 digital pins to show values .xx:xx (hours and minutes)
The plan was to make the display light up and setting the alarm to the
value i need to show (through a loop counting up to the value on hours
and a reset and a loop)
This means i don't need the timing functions of the chip. Neither do i
need the alarm or radio features..(I achually already snapped those
parts off the print)
Thanks in advance.
Stig
Jasen Betts
> Jasen Betts wrote:
>> On 2008-10-16, stigan...@gmail.com <stigan...@gmail.com> wrote:
>> > Hello,
>> > I have hacked a clockradio and i need to supply it with power from a
>> > 12v battery. How do i invert DC to AC?
>>
>> you have an LM8560 (or similar) based digital alarm clock and need a
>> two-phase precise-frequency AC to drive the display and timer ?
>>
>> As I understand it those chips don't actually need the negative part
>> of the AC (which makes your life easier) but they do need the
>> frequency to be right (or they keep time very poorly)
>>
>> MM5369 is a chip that can make the right frequency for you then you
>> just need to feed the output to some transistors to provide an
>> inverted signal and boost the current so it can drive your display
> The MM5369 has been obsolete for so long (20 years?) that National
> Semiconductor doesn't even list it as obsolete. Also, there were
> special versions like 100 Hz so if you find old stock, or surplus it may
> not be 60 Hz. Even companies like Jameco don't list the MM5369 any
> more.
I just cheked the local electronics shop and they listed 1 in stock.
> A better choice would be a crystal & divider chain, but keep in mind
> that some clock chips wand a 50% duty cucle at 60 Hz.
yeah, if you don't give them that half the display will be brighter than
the other half
> Digikey has a lot of suitable crystals. Fo instance, they have 60 kHz crystals starting
> at 72 cebts. Divide by 1000 and yo have 60 Hz.
what's a good way to divide a crystal by 1000 with a 12-15V supply?
I was thinking 2.457600 Mhz / 40960 using a CD4040 to drive the
crystal and divide by 4096 and a CD4018 to divide by 10 more and
provide a 50% duty cycle.
Bye.
Jasen
Michael A. Terrell
Jasen Betts wrote:
>
> On 2008-10-17, Michael A. Terrell <mike.t...@earthlink.net> wrote:
>
> > Jasen Betts wrote:
>
> >> On 2008-10-16, stigan...@gmail.com <stigan...@gmail.com> wrote:
>
> >> > Hello,
> >> > I have hacked a clockradio and i need to supply it with power from a
> >> > 12v battery. How do i invert DC to AC?
> >>
> >> you have an LM8560 (or similar) based digital alarm clock and need a
> >> two-phase precise-frequency AC to drive the display and timer ?
> >>
> >> As I understand it those chips don't actually need the negative part
> >> of the AC (which makes your life easier) but they do need the
> >> frequency to be right (or they keep time very poorly)
> >>
> >> MM5369 is a chip that can make the right frequency for you then you
> >> just need to feed the output to some transistors to provide an
> >> inverted signal and boost the current so it can drive your display
>
> > The MM5369 has been obsolete for so long (20 years?) that National
> > Semiconductor doesn't even list it as obsolete. Also, there were
> > special versions like 100 Hz so if you find old stock, or surplus it may
> > not be 60 Hz. Even companies like Jameco don't list the MM5369 any
> > more.
>
> I just cheked the local electronics shop and they listed 1 in stock.
I wouldn't touch that on a bet. I never buy singles of obsolete
parts.
> > A better choice would be a crystal & divider chain, but keep in mind
> > that some clock chips wand a 50% duty cucle at 60 Hz.
>
> yeah, if you don't give them that half the display will be brighter than
> the other half
You don't really understand the design, do you? Some of the dividers
need a 50% duty cycle, or they don't work, at all.
> > Digikey has a lot of suitable crystals. Fo instance, they have 60 kHz crystals starting
> > at 72 cebts. Divide by 1000 and yo have 60 Hz.
>
> what's a good way to divide a crystal by 1000 with a 12-15V supply?
Sigh. Use a 78L05 voltage regulator to power the oscilator & divider,
and a single transistor amp for level conversion.
> I was thinking 2.457600 Mhz / 40960 using a CD4040 to drive the
> crystal and divide by 4096 and a CD4018 to divide by 10 more and
> provide a 50% duty cycle.
You do realize that the higher the crystal frequency, the more power
the divider circuit uses, don't you?
Jasen Betts
>> I just cheked the local electronics shop and they listed 1 in stock.
>
> I wouldn't touch that on a bet. I never buy singles of obsolete
> parts.
Fair enough, by saying that I meant that my availability test was
inadiquate. (by 'just' I meant 'merely')
>> > A better choice would be a crystal & divider chain, but keep in mind
>> > that some clock chips wand a 50% duty cucle at 60 Hz.
>>
>> yeah, if you don't give them that half the display will be brighter than
>> the other half
> You don't really understand the design, do you? Some of the dividers
> need a 50% duty cycle, or they don't work, at all.
that's a surprise! I'd not expect timing to be that critical at such a
low frequency,
>> > Digikey has a lot of suitable crystals. Fo instance, they have 60 kHz crystals starting
>> > at 72 cebts. Divide by 1000 and yo have 60 Hz.
>>
>> what's a good way to divide a crystal by 1000 with a 12-15V supply?
>
> Sigh. Use a 78L05 voltage regulator to power the oscilator & divider,
> and a single transistor amp for level conversion.
so what's a good way to divide a crystal by 1000. giving a 50% duty
cycle?
512:488 might be close enough and you can get that using a CD4040 (or
similar TTL ripple counter chip) and and an 8-input and gate,
else if you need 50:50 you'll need a flip-flop too.
you're asking for a fair collection of parts...
>> I was thinking 2.457600 Mhz / 40960 using a CD4040 to drive the
>> crystal and divide by 4096 and a CD4018 to divide by 10 more and
>> provide a 50% duty cycle.
>
> You do realize that the higher the crystal frequency, the more power
> the divider circuit uses, don't you?
yeah, but the LED display would use much more anyway
anyway the original poster only needs a simple RC oscillator driving a
couple high-side transistor switches, as he's apparently not using the
timebase.
Bye.
Jasen
Michael A. Terrell
Jasen Betts wrote:
>
> On 2008-10-18, Michael A. Terrell <mike.t...@earthlink.net> wrote:
>
> >> I just cheked the local electronics shop and they listed 1 in stock.
> >
> > I wouldn't touch that on a bet. I never buy singles of obsolete
> > parts.
>
> Fair enough, by saying that I meant that my availability test was
> inadiquate. (by 'just' I meant 'merely')
>
> >> > A better choice would be a crystal & divider chain, but keep in mind
> >> > that some clock chips wand a 50% duty cucle at 60 Hz.
> >>
> >> yeah, if you don't give them that half the display will be brighter than
> >> the other half
>
> > You don't really understand the design, do you? Some of the dividers
> > need a 50% duty cycle, or they don't work, at all.
>
> that's a surprise! I'd not expect timing to be that critical at such a
> low frequency,
>
> >> > Digikey has a lot of suitable crystals. Fo instance, they have 60 kHz crystals starting
> >> > at 72 cebts. Divide by 1000 and yo have 60 Hz.
> >>
> >> what's a good way to divide a crystal by 1000 with a 12-15V supply?
> >
> > Sigh. Use a 78L05 voltage regulator to power the oscilator & divider,
> > and a single transistor amp for level conversion.
>
> so what's a good way to divide a crystal by 1000. giving a 50% duty
> cycle?
Divide by 500, followed by a divide by wo.
> 512:488 might be close enough and you can get that using a CD4040 (or
> similar TTL ripple counter chip) and and an 8-input and gate,
> else if you need 50:50 you'll need a flip-flop too.
>
> you're asking for a fair collection of parts...
Not really. Maybe $2 worth of CMOS, a crystal a couple caps a 2 cent
transistor and some nickle resistors. There are dual BCD counter ICs
like the mc14518 will give a clean divide by 100 followed by a divide by
five, and a divide by two, or use mc14040 and configure it to count to
500, then use a flip flop o divide by two.
I have seen oscilator modules that put out 60 Hz. Commodore used one
in their SX-64 computer, and I have seen them in some old battery backed
clocks.
> >> I was thinking 2.457600 Mhz / 40960 using a CD4040 to drive the
> >> crystal and divide by 4096 and a CD4018 to divide by 10 more and
> >> provide a 50% duty cycle.
> >
> > You do realize that the higher the crystal frequency, the more power
> > the divider circuit uses, don't you?
>
> yeah, but the LED display would use much more anyway
>
> anyway the original poster only needs a simple RC oscillator driving a
> couple high-side transistor switches, as he's apparently not using the
> timebase.
>
> Bye.
> Jasen
Jasen Betts
>> so what's a good way to divide a crystal by 1000. giving a 50% duty
>> cycle?
>
> Divide by 500, followed by a divide by wo.
>
>> 512:488 might be close enough and you can get that using a CD4040 (or
>> similar TTL ripple counter chip) and and an 8-input and gate,
>> else if you need 50:50 you'll need a flip-flop too.
>>
>> you're asking for a fair collection of parts...
>
>
> Not really. Maybe $2 worth of CMOS, a crystal a couple caps a 2 cent
> transistor and some nickle resistors. There are dual BCD counter ICs
> like the mc14518 will give a clean divide by 100 followed by a divide by
resistors cost more than caps?
> five, and a divide by two, or use mc14040 and configure it to count to
> 500, then use a flip flop o divide by two.
hmm, that 4518 looks like a CMOS part number :) 4018 can do the final
divide by 10 and give a 50% duty cycle (saving the flip flop)
so you can drive the crystal from a transistor? I've not seen that
done before.
> I have seen oscilator modules that put out 60 Hz. Commodore used one
> in their SX-64 computer, and I have seen them in some old battery backed
> clocks.
The clocks I've seen just used R-C oscilators, maybe 50Hz modules were
harder to get or my clocks were crap.
Bye.
Jasen
stigan...@gmail.com
How should i connect power to the ic of the clockradio if i just want
the display to work, being able to set the hours and minutes. (using
it to display other values i need to read out from my robotic devices)
As earlier described i need to power it from a dc supply.
Hope you can give me some advice on this issue, thanks
Stig
Jasen Betts
> How should i connect power to the ic of the clockradio if i just want
> the display to work, being able to set the hours and minutes. (using
> it to display other values i need to read out from my robotic devices)
> As earlier described i need to power it from a dc supply.
>
> Hope you can give me some advice on this issue, thanks
you still haven't said what chip it uses, I'll assume "8560"
because that seems to be the most popular one
build this: (view in courier font)
7V ----+------
|
+-[18K]-------|--------+
| | |
| +--------+ |
| | | |
| | . . . .|. . . . | +-[10K]---> Freq
| | . VCC(8) . | |
| | . . | |
| +--RES(4) OUT(3)--+-----+-----+-----------> D1
| . LM555 . |
+-------TH(6) DIS(7)--- | .---> D2
| . . | |/
+-------TR(2) CV(5)-- +--[560R]---| PN2222
100nF | . . |\| or BC337
===== . GND(1) . ~\
| . . . .|. . . . |
| | |
+-------------+-----------------------------+--
|
|
---+-- gnd
That should hit the ball park of 60Hz give approximately equal time
on each output and accept sufficient current to drive your LED display
Freq goes to pin 25 and D1 and D2 connect to the display.
if the display is too bright you may need to add some voltage drop by
putting (for example) 3 or 4 1N4001 diodes in series on D1 and D2.
(too bright will wear it out quiickly)
Bye.
Jasen
stigan...@gmail.com
hi Jasen,
Thanks for the schematics, It is an 8560 here is the datasheet, <<
http://www.paulanders.com/G5-LED/ver1/datablad.pdf >>
I don't find an lm555 just here in my pile of electronics, but i'd
like to ask if its nessecary to generate a frequency if i just need
the display to show me values given by sensors through my arduino. The
idea was to just use the chip to control the display saving some pins
on my arduino.
(sorry to be such a newbie)
In case i could hook it directly to the arduino with an external power
of 7v dc could i then just give let in 7v to pin 15 or and 20 (Vss,
Vdd)?
Stig
Jasen Betts
> hi Jasen,
>
> Thanks for the schematics, It is an 8560 here is the datasheet, <<
> http://www.paulanders.com/G5-LED/ver1/datablad.pdf >>
> I don't find an lm555 just here in my pile of electronics, but i'd
> like to ask if its nessecary to generate a frequency if i just need
> the display to show me values given by sensors through my arduino.
you need to generate a frequency, it doesn't need to be a precise or
even predictable frequency, anything between 30 and 100Hz is probably
fine, there is an aesthetic requirement is that it should be
approximately symmetrical.
> The
> idea was to just use the chip to control the display saving some pins
> on my arduino.
the chip only drives half the display at a time, you need some way to
switch halves rapidly enough to see the complete display.
> In case i could hook it directly to the arduino with an external power
> of 7v dc could i then just give let in 7v to pin 15 or and 20 (Vss,
> Vdd)?
the chip would not run, it need some sort of clock signal to be able to
measure how long the button inputs are active for, and to tell it which
LEDs its output pins will drive. (you see that pins 1 to 13 each drive
2 segments of the display depending on which half-cycle the AC supply
is in.)
>
> Stig
--
Bye.
Jasen