MTFCA Forum

I recently changed my acetylene head lights, in my 11 T, to LED lights based on an article in the Jan/Feb Horseless Carriage GAZETTE. Using the 3500K 6 watt COB bulbs I was very happy with the results. The light color is comparable to the gas lights. I didn't notice it at the time, but with the lights off and the engine running, I get a faint pulsating light from the LED bulbs. I've disconnected everything, including any feed to the lights, and running on the mag I have the issue. With disconnecting the Mag and running on the battery I have the same issue. I've come to think the Buzz coils are involved.
Has anyone changed to LED's. THOUGHTS?
Keith,

Does the frequency / speed of the pulsation vary with engine speed. Try putting filter caps across the headlight wires as close to the bulbs as possible. The caps will act like a filter and short circuit the pulsating ac voltage. while not affecting the dc voltage going to the Leds.the long wires going to the headlights can act like a antenna and pick up the pulsating ac which is like a short range radio signal. Spark coils were used in the earliest radio transmitters and can generate a intense RF field. If the wires to the leds are disconnected at the base of the bulbs does the pulsation go away. regardless the filter capacitors should eliminate the problem

Thanks Jim, I visually checked the speed of the Pulsations. As best I could tell they did change with speed. My wiring runs thru the 1/4” ID gas hose to 1/4 OD by 3/16 ID brass tubing used by the acetylene system. Makes a clean and neat system, but one with limited room. Would the brass tubing magnify the signal? The light on the distributor side is brighter. I also have a smoked LED light bar at the rear and the running lights also flicker dimly. No lights up front other then the headlights. How small a capacitor be available?
Keith

Keith. Sounds like You have a nice set up. light wires hidden in the gas line. The metal gas line can act like a antenna and pick up stray ac voltage from what appears to be the vibrating coils. several ways to go at it. After writing a page full of suggestions I thought of another simple fix that just might work with less effort. take a small tail light bulb and connect it to the power wire going from the light switch to the lights.and the other wire to ground. The bulb will be connected all the time and will light up when You have the lights on but draws little power and when You turn the lights off acts like a load to bleed off the pulsating hash. You can paint it black if You like. Let me know the results. Jim

Thanks for your comments Jim. Tried the light bulb and still pulsating. I guess the brass antenna is to strong. I suppose I should consider it free energy and live with it.
Keith