Fastest incandescent lamp?

What type of low voltage incandescent would be best to use for fastest response time, or is there any difference?

I'm looking for a approximate 2 watt low voltage lamp to use with a electronic roulette wheel. The pulse width is about 15 milliseconds when the wheel starts and gets wider from there as the wheel slows down. I tried using a 12 volt, 3 watt lamp with some bias to keep it warm but that didn't help much. The lamp is fairly dim on short short pulses with or without the bias.

Is there any particular incandescent lamp that is better than others in terms of response time?

-Bill

Reply to
Bill Bowden
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For a given filament temperature (and thus life, intensity and color), there's a certain amount of mass (volume) behind the surface area emitting that light. Your best bet would be grain-of-wheat types, if smaller don't exist (grain of dust lights? LOL).

Trivia: you can operate incandescents up to many kHz, but it's a small delta T (small delta intensity) at a high bias temperature (where heat loss is rapid = high thermal slew rate).

Tim

-- Deep Fryer: a very philosophical monk. Website:

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Reply to
Tim Williams

Yes, I thought of using white LEDs but I don't think a single LED would be bright enough and has a narrow viewing angle. Most of the light would go straight up to the ceiling. I suppose the Luxon star 1 watts might work, but are too expensive.

Anyway, I picked up a couple 14 volt 120mA bulbs at Radio Shack today for $1.71. I'll give them a try and report back. They are cheap enough to run at higher voltage with a little less lifetime.

Do you know what the reduced lifetime would be running at excessive voltage?

-Bill

Reply to
Bill Bowden

If response time is an issue, why not convert to LEDs?

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

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Home of DaqGen, the FREEWARE signal generator

Reply to
Bob Masta

Life expectancy is roughly inversely proportional to the applied voltage raised to the 12th power.

So rumor has it.

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Cheers, John

Reply to
John - kd5yi

for your lamps you could try a series capacitor with a parallel resistor ad drive them with a higher voltage.

you may do better switching to some other type of display.

neons are fast but not low voltage,

LEDs are fast and low voltage.

Bye. Jasen

Reply to
Jasen Betts

Yes, I hooked up the 14 volt, 120mA Radio Shack lamp and the results are impressive. With a 15 millisecond pulse, the bulb lights up white with no orange color at all. Looks like this bulb will be usable.

The only problem is the rated lifetime is only 30 hours. Seems a bit short to me, maybe it's a misprint?

-Bill

Reply to
Bill Bowden

In general, higher voltage bulbs of the same wattage will turn on and off faster, because their thinner filaments have a higher surface to volume ratio. A 4 watt 120 volt night light lamp should have a higher flicker frequency capability than a 12 volt 4 watt lamp.

Reply to
John Popelish

I have an old bicycle flasher that uses a 9V battery to drive a 6V bulb. It is very bright, but the flashes are very brief. At about 2 flashes per second, it has run hundreds of hours without bulb failure, while I've gone through many batteries over the years. This was a complete surprise to me, since I knew about the 12th power law, and also expected that the power bursts would cause some sort of thermal / mechanical fatigue.

So as long as your flashes are short, you may likewise get a long bulb life. YMMV

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

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Home of DaqGen, the FREEWARE signal generator

Reply to
Bob Masta

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