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Suitable 32.768KHz oscillator for Pulsar Modules...read on..

For electronic related stuff like module repair, silver epoxy fixes etc.
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retroleds

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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post26 Jul 2010, 03:07

clockace wrote:so i been snookered???? :oops: peter
Who knows.

Further thoughts: 2 original 355 batteries , of only 60-80mah capacity each. At 20 time checks a day, the display is used for 6+ hours a year. Meanwhile, the oscillator circuit has to run continuously, 24 hrs. a day. The possible power left for heating up the chip(after the power needed for the display is subtracted) would be truly minuscule. Hopefully an engineer type with time and the correct numbers will crank the numbers and give us some idea how much, if any battery energy would be left for conducting heat, considering the drain of the display, while still giving approximately a year of battery life.

My original purpose in examining those traces was to determine if they could be bypassed with a resistor of correct resistance, to regain function. No good deed goes unpunished. :lol:
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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post26 Jul 2010, 09:44

rewolf wrote:
retroleds wrote:... Mr. Klien claims he was told by a Pulsar engineer that those traces are there to extract heat produced by the IC. I'm thinking that is the most implausable explanation I have heard yet regarding their intended function. ...
That's rather easy: they are actually negistors, not resistors, i.e. they have negative resistance.
A resistors heats up when current is forced through it, but a negistor induces current when heated up, similar to an inductor in a variable magnetic field. It is a combination of the Seebeck effect and the Peltier effect.
In the Pulsar, this heat-induced current is used to drive the oscillator. A very clever way to retrieve some of the battery energy turned into heat by the rest of the circuitry - so the oscillator runs on "free" energy, prolonging battery life. And, 2nd effect, it helps cooling the chip - the Pulsar is nothing but a (time) computer, and as we all know from our personal computers, proper cooling is essential for the main chip.

I'm totally serious! Engineers never kid laymen - granted!

HEY, THIS WAS A JOKE! It's total bullshit!
Either I should have added some smilies or now YOU fooled ME making me think you took this for serious ;-)
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post26 Jul 2010, 20:27

AAAAAAHHHHHHHH!!!! some of us are soooooo gullible. :oops: peter
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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post26 Jul 2010, 20:57

rewolf wrote:
rewolf wrote:
retroleds wrote:... Mr. Klien claims he was told by a Pulsar engineer that those traces are there to extract heat produced by the IC. I'm thinking that is the most implausable explanation I have heard yet regarding their intended function. ...
That's rather easy: they are actually negistors, not resistors, i.e. they have negative resistance.
A resistors heats up when current is forced through it, but a negistor induces current when heated up, similar to an inductor in a variable magnetic field. It is a combination of the Seebeck effect and the Peltier effect.
In the Pulsar, this heat-induced current is used to drive the oscillator. A very clever way to retrieve some of the battery energy turned into heat by the rest of the circuitry - so the oscillator runs on "free" energy, prolonging battery life. And, 2nd effect, it helps cooling the chip - the Pulsar is nothing but a (time) computer, and as we all know from our personal computers, proper cooling is essential for the main chip.

I'm totally serious! Engineers never kid laymen - granted!

HEY, THIS WAS A JOKE! It's total bullshit!
Either I should have added some smilies or now YOU fooled ME making me think you took this for serious ;-)

:oops: I was a bit wound up when I typed up that response(not over this thread, some personal stuff going on with one of our kids...seemingly they are in some crash and burn mode with their life). I took it at face value and thought,"damn that is an irritating, silly idea". Writing under stress or conditions of fatigue is never a good idea. Ditto with watch repair - best done when you are feeling totally calm and analytical. :lol: 8-) I will take a chill pill. ;*
“No persons are more frequently wrong, than those who will not admit they are wrong.”
― François de La Rochefoucauld
http://www.retroleds.com - Sales of vintage LED, LCD, analog watches, parts and gadgets - repair tutorials & tips.
http://www.thedigitalwatch.com - Huge database of digital timepieces. All content from ledwatches.net is going here.
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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post04 Aug 2010, 09:18

retroleds wrote:...My original purpose in examining those traces was to determine if they could be bypassed with a resistor of correct resistance, to regain function...

With all we know by now, this should be possible!

To sum it up: they are simple resistors. No heat spreader, no temperature compensation, no heat compensator, no inductor, no capacitor, etc. Just simple resistors with ~90kOhms resistance.

However, you have to consider that if you "bypass" them with an SMD resistor, you will in fact connect the original and the bypass resistor in parallel, so the resulting resistance is NOT simply the value of the bypass resistor, but always less. And if the residue of the original resistor shows some awkward variable behaviour, the combination with a bypass resistor will also be variable, but to a lesser extent.

The formula is: R = 1 / ( (1/Ro) + (1/Rb) )
R=resulting resistance, Ro=actual resistance of original resistor, Rb = bypass resistor; all values in kOhm.

Or, to calculate the required bypass resistor: Rb = 1 / ( (1/R) - (1/Ro) ). With desired R=90k, this results in: Rb = 1 / ( 0.0111 - (1/Ro) ).
(You will find that if you insert Ro less than 90kOhm in the formula, the bypass resistor needs negative resistance - voilà, a negistor :mrgreen: )
Last edited by rewolf on 04 Aug 2010, 13:28, edited 4 times in total.
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post04 Aug 2010, 10:30

so the discussion proved useful.
end of story :)
many thanks to Dennis for posting the same explanation on his forum.
"The first and still only LED watch maniac in the East Block" - www.crazywatches.pl
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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post04 Aug 2010, 13:35

rewolf wrote:
retroleds wrote:...My original purpose in examining those traces was to determine if they could be bypassed with a resistor of correct resistance, to regain function...

With all we know by now, this should be possible!

To sum it up: they are simple resistors. No heat spreader, no temperature compensation, no heat compensator, no inductor, no capacitor, etc. Just simple resistors with ~90kOhms resistance.
I'll have to take another test of those with something over them to avoid the possibility of humidity being a factor in their resistance change - it appeared that they were temperature sensitive when I originally did my tests. If they have became moisture sensitive due to deterioration, that would really suck. I am assuming they would have been originally designed to be moderately stable despite variables in humidity, brought on by off gassing of batteries, or just battery changes during humid weather.
“No persons are more frequently wrong, than those who will not admit they are wrong.”
― François de La Rochefoucauld
http://www.retroleds.com - Sales of vintage LED, LCD, analog watches, parts and gadgets - repair tutorials & tips.
http://www.thedigitalwatch.com - Huge database of digital timepieces. All content from ledwatches.net is going here.
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Re: : Suitable 32.768KHz oscillator for Pulsar Modules...rea

Post04 Aug 2010, 14:01

retroleds wrote:... I am assuming they would have been originally designed to be moderately stable despite variables in humidity, brought on by off gassing of batteries, or just battery changes during humid weather.
They ARE stable, but only if not contaminated. They certainly should better have been covered/sealed at the production stage to keep them stable.
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post04 Aug 2010, 14:49

I'll feel really stupid if I find the resistance is stable under temperature changes when covered with something like thin cellophane. An incredible oversight for me not to have considered the effect the humidity from my breath might have had on uncovered resistors. The resistance changes were almost instantaneous....this will be interesting.
“No persons are more frequently wrong, than those who will not admit they are wrong.”
― François de La Rochefoucauld
http://www.retroleds.com - Sales of vintage LED, LCD, analog watches, parts and gadgets - repair tutorials & tips.
http://www.thedigitalwatch.com - Huge database of digital timepieces. All content from ledwatches.net is going here.
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post04 Aug 2010, 18:32

I have no idea what contamination could do to the chemical or electrical properties of TaN resistors, but I could imagine that such an altered resistor would also be less temperature stable than in its original state.
And heating it up will also dry it - maybe that's why the "heat-cure" sometimes helps (temporarily).

The meandering structure of these resistors makes them very susceptible to contamination or even moisture alone: if you cover them with any conductive substance, the currrent will not only flow the "long way" as intended, but also the short way accross the meanders, decreasing the resistance. And (battery) acid with water/moisture is a very good conductor - at least compared with a 90kOhm resistor. OTOH, acid could also etch away some of the TaN and thus increase resistance or even break the circuit.
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post04 Aug 2010, 18:41

They appear to be the weakest link in an otherwise fantastic feat of engineering. Damn.
“No persons are more frequently wrong, than those who will not admit they are wrong.”
― François de La Rochefoucauld
http://www.retroleds.com - Sales of vintage LED, LCD, analog watches, parts and gadgets - repair tutorials & tips.
http://www.thedigitalwatch.com - Huge database of digital timepieces. All content from ledwatches.net is going here.
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: Suitable 32.768KHz oscillator for Pulsar Modules...read on

Post19 Oct 2011, 22:54

I was inspired by Handy's Oscillator mod as I had a working P3 module which died with the dreaded single digit disease.

I tried all the obvious crystal changes, warming, vinegar baths but to no avail.

I did a little more trawling and came up with a smaller Swiss oscillator chip ironically made by an offshoot of the Swatch group. This oscillator offers +/- 20ppm and .3/.5 uA consumption.

It was very fiddly to fit, but I persevered with a 10x eyeglass and BINGO
I now have a working P3 module again.

The chip I used was a Micro Crystal OV-7604-C7

This is a great forum !
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Re: Suitable 32.768KHz oscillator for Pulsar Modules...read

Post10 Apr 2013, 20:32

I recently installed an external Oscillator module for my P3 as it had the infamous single "0" condition. Replacing the crystal didn't product any clock signals so I installed an external one. Module is working perfectly but I did notice the LED display was much brighter than my other Pulsars. Do I need to install a resister to attenuate the display drivers or is the external oscillator independent of the amount of current being supplied to the LED display? I've attached a picture of an attempt to revive another module and checked that the oscillator chip was functional however as you can see only the top row of LEDs are lit so I think this module cannot be revived.
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