E-Brake Tung Sol Flasher

[Ron B.]

Perhaps someone with electrical savy can help me understand this. My '57 came with the e-brake alarm. The flasher that came with it was a Tung Sol 550. It was DOA. I came across a brand new Tung Sol 624...same size and shape...inside looks exactly the same. Yet...it will not light a #90 bulb at all. It will light a test light, but not correctly. Actually the test light bulb sort of flutters, for lack a better expression. Can anyone explain, in layman's language, why this doesn't work and how I might be able to make it work?
I appreciate any help. Thanks.

[Jack H.]

Re: E-Brake Tung Sol Flasher

These types of early flasher modules are typically based on a bi-metal contact element. When the circuit switch closes, current runs from the battery through the lamp(s) and flasher to ground.

That current heats the bi-metal element in the flasher and when it reaches sufficient temperature, it changes shape and opens the circuit. Current flow stops and the bi-metal cools. Get the picture?

The flasher, by model number, is designed to function with a pre-defined current. The current is dictated by the lamp's filament resistance and the number of lamps in the circuit.

So, get the wrong flasher in a given circuit and it might pass current and NEVER heat sufficiently to open and begin the blinking cycle. Also, get the wrong lamps in the circuit and they might blink but at a MUCH faster or slower rate than expected.

Get everything right and the world is a 'happy' place...

[Ron B.]

Re: E-Brake Tung Sol Flasher

Thank you very much for a clear explanation of the theory. Let me see if I can figure this out . Since the bulb comes before the flasher in the circuit, a bulb with less resistance i.e. the bulb in the tester, would allow more current through to the flasher, and conceivably heat it up and the bulb would light and blink. Am I even close to a solution, or terribly confused?

[Rob M.]

Re: E-Brake Tung Sol Flasher

The higher the current the longer the bi-metal will break the circuit. so if the lamp is more off then on the lamp draws too much current, if it is more on the off it draws to little current...

[Ron B.]

Re: E-Brake Tung Sol Flasher

Hi Rob,
Thanks very much for your answer. I appreciate your help with the explanation. Ron.