[Fot] Technical Question

Randall TR3driver at ca.rr.com
Wed Feb 12 22:19:03 MST 2020


> Metal oxide semiconductor field effect transistor I think. 
> That's about all I know about MOSFETs!

MOSFETs basically have a very thin layer of glass between the control
element and the rest of the transistor, giving them a very high input
resistance and hence easy to control from a microprocessor that has only
logic level outputs.

They also can be designed with very low resistance in the ON state, making
them ideal for handling high currents.  I use some older ones (that I got
for free) that are good to 12 amps or so; while there are versions available
that can handle 500 amps (probably even more by now).

Didn't really need a MOSFET here, but that's what controls the center brake
light in this (very brief) video
https://youtu.be/q4GMcD9DktQ

But unlike Bill, I didn't bother with using a microprocessor.  The 4 blinks
are provided by an old fashioned NE556 integrated circuit.  Sometimes simple
is better.  The entire circuit, including active current limit for the LEDs
and some more LEDs to provide a license plate light (not shown), is located
inside the center brake light.

-- Randall 
56 TR3 TS13571L once and future daily driver
71 Stag LE1473 - awaiting engine rebuild
71-2-3 Stag - awaiting gearbox rebuild 




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