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Re: [Phys-l] win/win solution for light bulbs

Traffic light fixtures still use the same 120 VAC wiring as the incandescent heaters did !!!!!

There is a current limiter (capacitor) in some of them.
Some use a simple transistor circuit.
The LED exit signs around here seem to use the capacitor current limiting scheme.

Todays experimentation indicates that if you bypass the simple current limiting circuit - that 10 - 12 volts AC will light them nicely. We didn't measure the total current draw yet but they seem to be series strings of 5 or 6 (red) LEDs, hooked up in parallel with half lighting on each cycle of the AC.

These modules were 'scrapped' because the major 'pass' transistor was fried and removed before being cast-off.

Your local 'traffic light' agency should have a 'few' rejects lying around.
All the LED's are working.

At 1:24 PM -0700 on 5/1/07, Bernard Cleyet wrote concerning Re: [Phys-l] win/win solution for light bulbs :

bc, amazed at the rapidity of the signal lamps' replacement in CA.p.s. major problem till 110 V. led developed. i.e. now requires the same
p/s as the CFLs + rectifier? -- imagine all on one chip! Or house wired
for 3V.?