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What is the smallest voltmeter?

I second that idea. Though I'd probably go with a Cree LED if using more than one - they don't sell "bin numbers" their LEDs either meet specification or they don't sell them.

I put 56, 13,000 mcd, white LEDs in an auxiliary light on my motorcycle and it is very bright - easily enough for a bicycle under most conditions. In daylight it is more noticeable than the headlight low beam. Burns 3.4 watts and outshines the 50 watt low beam. Only cost $9 Beam angle on that is only +/- 10 degrees - so it won't replace the low beam at night

I have four Cree red LEDs in the tail lamp and it is way overkill . . I should have used just two. At $8 each Beam angle on those is 120 degrees

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Yes, LEDs are definitely more efficient. I have designed a current regulated driver for strings of Cree LEDs. My friend Tony

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is making a diving flashlight that will have either 7 or

13 of the 3 Watt LEDs (which requires up to about 50 VDC). My circuit (using a PIC and a boost converter) produces 750 mA from 10-14 VDC, and it has a low power mode which drives the LEDs at only 100 mA, which is still plenty bright. The circuit board is only 1" x 2". It also senses low battery condition and then flashes the LEDs to conserve power and also provide a warning. I'll be getting boards made soon. All the parts are maybe $10, and you can reprogram the PIC if you want other features or different output currents. It has about 90% efficiency. Let me know if you would like one of the boards for your project or others.

Paul

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Paul E. Schoen

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