"Ignoramus8558" wrote in message
.. .
We were playing with my son last night and made a toy railroad
gate. It would open and close based on a relay signal from a
momentary
switch that is activated when a train comes near the railroad
intersection.

It worked, kind of.

My problem is that the DC motor (pulled from a demolished HP X-Y
recorder) would overheat from being under power constantly.

I would like to find a little 12 VDC motor that could survive a
locked
rotor condition indefinitely, or some other simple solution. A
little
solenoid with a dual coil (pulling and holding) also comes to mind.
I
need something that can be bought for a few bucks at most or made
easily, and I am out of ideas.

i



555 timer circuit to supply full current for 110% of the time it takes
to operate the gate, then fall back to 10% current.

I did a very similar thing on a dc motor that advances the tool turret
of my small cnc lathe. It positions the toolpost, then falls back to a
lowish current to hold the motor against a dentent, only difference
was that this motor had to run forwards to position, over-run a
ratchet then reverse onto the ratchet stop then reduce the current.

AWEM