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Amplifier transistor matching?

Measuring and matching used batteries is not that difficult, if you need to use them in pairs. Also, some sources for used batteries are applications where they were originally used in pairs. I collect and cull AA's from RF mics all the time with little ill-effect. Sometimes I come in from a gig with my pockets literally bulging with AA's. I usually just match them by open-circuit voltage and put them in different piles matched within a 0.1 or .05 volts of one another. Anything below 1.4 volts, I usually either relegate to the kids' CD/Mp3 players or discard.

It saves me hundred$ a year, at least.

jak

Reply to
jakdedert
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"Watson A.Name - "Watt Sun, the Dark Remover""

OK. Suppose we have a circuit that draws 20 milliamps at -3v, and 220 milliamps at +3 volts. And suppose our power supply is four 1.5v 2200mAh batteries, wired so one pair provides +3v, and the other pair provides -3v.

Is it possible to redesign the power supply to do better than replace the

+3v pair of batteries every 10 hours, and the -3v pair of batteries every 110 hours? (So for 110 hours of operation, we'd need to replace 12 pairs of batteries.)

Tim

Reply to
Tim Martin

Make a switching powersupply using 6V input and outputing two 3V voltages?

Use a latching relay to switch the batteries (3V -3V) every once and a while?

Reply to
Kristian Ukkonen

2200mAh

provides -3v.

the

every

pairs of

I would use a DC-DC converter to get the minus 3V, at 20mA. SHould take just a 555 and a cap and a couple rectifiers. A V doubler with a zener seems like it would do the trick.

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if But use a CMOS 555 if the supply is less than 5V. But the CMOS 555 may not source enough current, I'm not sure how much it can handle.

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This one is already assembled.

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It doesn't have to be this fancy.

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Reply to
Watson A.Name - "Watt Sun, th

2200mAh

provides -3v.

the

every

pairs of

Seems like a lot of extra effort and expense for no net benefit. If you improve the circuit by converting the 6V to +/- 15V instead, (assuming that does provide some benefit for the circuit involved) at least there may be some point to it all. Otherwise it would probably be easier to provide a battery low indicator for each pair of cells.

MrT.

Reply to
Mr.T

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