REFLECTOR:A (re)volting problem

Chuck Jensen reflector@tvbf.org
Fri, 3 Oct 2003 09:43:08 -0400


The plot thickens.  Yesterday evening, I went out to get my night landings
in for currency and tested the pitot.  I pushed in the circuit breaker and
turned on the pitot switch.  After 5-10 seconds, the "10" (amp, I assume)
breaker popped.  I cycled it again, same results.  I checked and the voltage
dropped from 12.8v to about 11.0v, then the breaker would pop after a few
seconds.

Based on my passing understanding of electricity (I once passed by the
Electrical Engineering building), when you go up in volts, you go down in
amps.  I assume the converse holds true; when the voltage is cut in half,
the amps double?  So, an instrument rated for 10a at 24v is going to need a
20a circuit at 12v (actual draw is approximately 80%, or 16a)?

Is that thinking correct?  Or is there some squaring and doubling going on?
If the circuit has 14 gauge wire, can a 20a push button breaker be safely
used or is that asking impolitely for trouble?

Chuck, coming up short of a perfect solution.