One of the newsgroups had a neat idea on checking the capacity of rechargeable batteries. The idea is to take a quartz analog clock and add a parallel load resistor with the battery connector. The clock runs until the resistor depletes the battery enough to stop the clock - giving you an idea of how much charge the battery is able to hold. Great idea for those old questionable batteries you may have lying around.
Resistor is sized for point one times the amp hour capacity of the battery. An AA NIMH with a 2,000 mah capacity would get a ~6 ohm 1/2 watt resistor to drain it at a rate of ~200 milliamperes an hour.
The author posted no links to the originator.
So, I'm fooling with a picaxe and wanting to test/calibrate the time delay and decide to try the quartz clock idea as an automatic timer. All part of the of using the AD to set long time delays with a resistor.
I cut a 1/2" wood dowel to 1-3/4" long drilled the ends and put a couple of small round head brass wood screws and tightened down a red/black wire on the screws. The dowel replaces the AA battery in the clock and gets wired to the picaxe output pin.
Instant hassle free calibrator for long time delays. I'm running the picaxe at 3 volts and used two silicon diodes, forward biased, to drop 1.2 volts so the clock sees ~1.5 volts.
I had to add a 300 uf 6 volt cap across the dowel before one of my clocks would work (the clock needed a low impedance source to drive the impulse motor in it).
Resistor is sized for point one times the amp hour capacity of the battery. An AA NIMH with a 2,000 mah capacity would get a ~6 ohm 1/2 watt resistor to drain it at a rate of ~200 milliamperes an hour.
The author posted no links to the originator.
So, I'm fooling with a picaxe and wanting to test/calibrate the time delay and decide to try the quartz clock idea as an automatic timer. All part of the of using the AD to set long time delays with a resistor.
I cut a 1/2" wood dowel to 1-3/4" long drilled the ends and put a couple of small round head brass wood screws and tightened down a red/black wire on the screws. The dowel replaces the AA battery in the clock and gets wired to the picaxe output pin.
Instant hassle free calibrator for long time delays. I'm running the picaxe at 3 volts and used two silicon diodes, forward biased, to drop 1.2 volts so the clock sees ~1.5 volts.
I had to add a 300 uf 6 volt cap across the dowel before one of my clocks would work (the clock needed a low impedance source to drive the impulse motor in it).