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 Post subject: Supply Voltages
PostPosted: 09.12.2004 09:48 
This is an awesome project, just what I've been looking for.
I wired it all up on a breadboard just as in the schematic, but it does one of two things depending on the resistor between pins 2 and 7. (this is just with the pnp bjt bit, not the npn)
If the resistor is 15k, the led will start on, and fade off and never come on again. If the resistor is 94k, the led will just stay on. When I add the npn bit, the led connected to the npn bjt just stays on regardless.

- Do the values of the resistors between pins 1-5 and pins 5-7 have to be the values stated in the schematic? If not, what happens if they are not?

- Does it make a difference to fading if the voltage supplied to the LM324 is different to the voltage supplied to the LED's?

I know a fair bit about electronics, but this one has me stumped :(.


 Post subject:
PostPosted: 09.12.2004 10:18 
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Wondering too much off that 100K will make the circuit behave incorrectly. That is because the timing part of the circuit might work the other way around but not back again because of too high/low value of the resistor. Also the cap is important too. Don't just slap something to replace it with, try it first with the one that I used in my article and experiment from there.

Current draw from the led can also cause strange behavious but I have never had any trouble with properly calculated current limiting resistor. Also the supply voltage shouldn't affect the operation that much. At least I didn't notice anything out of the ordinary but I didn't test it with that many different voltages in the first place...

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 Post subject:
PostPosted: 09.12.2004 10:41 
Woah, speedy reply.

Cheers mate!

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