Lantern Mantles? Coleman or generic?

1967, I was in charge of the night shift building an earth dam. The management of the engineering company was concerned for my safety around all that heavy equipment, but I assured them, that, with my Coleman lantern, I was the most visible person on the site. Besides, who else could make the 11PM run to the hamburger joint? Gerry :-)} London, Canada
Reply to
Gerald Miller
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If you're going to the trouble of putting a switching power supply in a flashlight, might as well make it a step-up circuit that can operate from a single cell. This way, you can drain the cell completely without worrying about hurting it. (The problem with draining a series pack of cells completely is that one goes flat before the others and is damaged when the others try to charge it in reverse.)

This circuit says it will drive any LED from a single 1.2-volt cell, and that it regulates the brightness as the cell drains:

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Reply to
Colonel Mustard Green

There are a lot of single cell flashlights on the market and they typically have a white LED. White LEDs need about 4.5 Volts. That is exactly how they do that.

The original topic of this thread was around battery capacity. Volts can be converted as you please, but how many Amp-hours are in the battery determines the run time for any given load.

Reply to
Winston_Smith

Interesting circuit, a strangely drawn multivibrator at its core, but would have only moderate efficiency with the bipolar transistors and large base drive. Perhaps only 60% since the 3904's have pretty poor beta gain and are relatively slow. Mosfets like the 2N7000 would be vastly superior but would require most all values changed except the inductor.

I'd suggest two cells with one of the LTC drivers that provide efficiencies of >85% plus you can program drive, in effect an intensity control, to save even more power.

If you're worried about driving one of the cells negatively just parallel both cells with a schottky diodes in reverse.

And watch out for EMI/RFI! Both circuits will yield lots of interference unless shielded.

Reply to
Curly Surmudgeon

If your problem is "going through" rechargeable batteries the "AA cell in a D cell adapter" solution isn't going to be much help.

The best NiMH AA cell has 1/4 the available amp-hours of power of the average alkaline primary cell, meaning it has to be recharged 4 times as often. And since each rechargeable battery has a finite life in numbers of recharges before failure...

Spend the money for the highest amp-hour D-cell NiMH cells you can find, which will be 10 AH or better. Then you get the most power with the least recharges, and also the longest overall life.

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Reply to
Bruce L. Bergman

thanks for that

Reply to
Myal

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