>Date: Mon, 10 Aug 1998 14:01:18
From: "Robert L. Nuckolls, III" <nuckolls@aeroelectric.com>
>Subject: Re: RV-List: Re: COZY: Re: do it yourself strobes . . .
>
>
>>I recall the article as well. If memory serves (no garantees), the writer
>>did NOT use flash tubes and capacitor discharge.
>>
>>Was a seemingly simple method of using 50 Watt Halogen bulb switched on and
>>off via simple 555 timer and, if I remember correctly, a power FET.
>
> This would be a clone of the AeroFlash incandescant fixtures used
> on thousands of Cessnas since about 1967. I was at Cessna when the
> roating beacon was being replaced with the flashing incandescant
> lamp . . . wasn't impressed. The fade-in-fade-out characteristic
> of the filament lamp was (IMHO) less attention getting than the
> sharp pulse of light you got from the rotating mirror assembly
> of then popular 36 watt beacons. Further, the lamp used then
> (and still) is 150 watts . . . about 12+ amps!!!! We had to add
> a resistor to the system so that when the lamp was off, we were
> dumping an equivalent amount of power into the resistor to make
> the load on the system more constant . . . pulsing of the panel
> lights at night would drive you nuts.
>
>>Drawback in my mind would be the heat of 50 Watts through the FET. Duty
>>cycle would make it cooler and a heat sink would certainly be required.
>
> No problem these days. Power FET's with .007 ohms on resistance
> are quite common. A 12-amp load makes these devices disipate
> only 1 watt! Easily handled with very small heatsink. A feature
> of one of our turn-key wiring kits will inlcude solid state relays
> for nav, landing, taxi lites and pitot heat . . . no heavy currents
> through panel mounted switches.
>
>>The bulbs come in a number of 12 volt flavors from low voltage
>>track-lighting to H-3 auto headlight bulbs. Also available in lesser or
>>greater wattage ratings.
>
>>
>>Might be worth investigating. I have no way of determining the lumens
>>(candlepower) output of these things. Anyone know if such an animal would
>>meet the FAA requirements for visibility?
>
> Given that FAR23 requirements do not apply to amateur built
> airplanes, I think a 150W halogen lamp pertched on top
> of your vertical fin under a baby food jar might impress
> your inspector enough to get you signed off. You have
> a strong precedent in the Cessna experience. Plan on
> needing the dummy load to keep the system voltage from
> pulsing when this size lamp is flashed.
Bob . . .
AeroElectric Connection
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