Strange mixer inputs

[Doug Tymofichuk]

On Mon, 4 Oct 1999 16:16:29 -0400 KA4HJH <ka4hjh at gte.net> 
wrote:

 
> Sounds like a ballast. Non-linear thermistor.
> 
> There was a guy whose model train kept derailing and 
> shorting out his electronic throttle, frying transistors, 
> blowing fuses, or tripping breakers constantly. He was too 
> lazy to fix the track, but fortunately a friend suggested 
> putting a 12V taillight bulb in series with the throttle. 
> Now every time there was a short the filament heated up 
> from the increased current, increased its own resistance, 
> and limited the current enough to prevent anything from 
> blowing.
> 
> Don't know if that's what's going on here but it's a good 
> story.

This is an old but effective trick for current limiting. If 
you need to charge 12 volt gel-cell batteries from a 
vehicle, a brake lamp makes a very effective current 
limiter. Or if you are repairing the output section of an 
amplifier, putting a 40 watt lamp in series with the AC 
power will protect it if there still is a short circuit 
present when you first power up.
----------------------
Doug Tymofichuk
dougt at cancerboard.ab.ca