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Fastest incandescent lamp?

Discussion in 'Electronic Basics' started by Bill Bowden, Nov 21, 2005.

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  1. Bill Bowden

    Bill Bowden Guest

    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
     
  2. Tim Williams

    Tim Williams Guest

    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
     
  3. Bob Masta

    Bob Masta Guest

    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
    www.daqarta.com
    Home of DaqGen, the FREEWARE signal generator
     
  4. Jasen Betts

    Jasen Betts Guest

    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
     
  5. Bill Bowden

    Bill Bowden Guest

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

    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
     
  6. John - kd5yi

    John - kd5yi Guest


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

    So rumor has it.

    http://members.misty.com/don/bulb1.html

    Cheers,
    John
     
  7. 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.
     
  8. Bill Bowden

    Bill Bowden Guest

    In general, higher voltage bulbs of the same wattage will turn on and
    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
     
  9. Bob Masta

    Bob Masta Guest

    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 <g>

    Best regards,




    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
    Home of DaqGen, the FREEWARE signal generator
     
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