Model Forum / Radio Controlled / Land Models / July 2003

it's a pot and/or multiposition switch being turned by a servo.

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DEWorley
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They use a rotary switch that dials in less resistance with each
step. The switch is attached to a servo. You get three forward speeds,
and one reverse speed.

Rick R.

its a simple switch plate. It has a wiper arm thats driven by a throttle
servo.
The plate has 3 contacts in the forward side and three in the reverse side
(usually). The contacts feed the battery current through a pair of big assed
resistors like so:
Slow speed: current runs through both resistors
medium speed: through one resistor
fast: neither resistor

reverse works the same but polarity is reversed to the motor.
You said in your post "1 step reverse"
Thats less common, but conceptually the same. instead of three reverse
steps, you only have one contact that gives you medium or maybe fast speed
(backwards)

If you have one in front of you, its quite easy to understand.