[GreenKeys] Model 15 Governed motor, tuning fork.

[Harold Hallikainen]

On Mon, September 29, 2025 12:29 pm, hwhall--- via GreenKeys wrote:
> This seems like an opportunity for invention for someone. How hard would
> it be to build a device that reads the governed motor speed & can
> automatically adjust the motor for any speed desired? I've not worked
> with one but it sounds like they could be controlled by PWM since
> governor contacts opening & closing sound like a sort of PWM. 
>
> (standing by to learn that this has already been tried & why if didn't
> work)
>
> Wayne
> WB4OGM

Interesting idea! I wonder if the governed motor has enough speed range to
cover the speeds we want. Maybe if it was geared for the highest speed and
slowed down with PWM and a tach, that could work. As I recall, the
governor in a Teletype is a switch that shorts out a resistor in series
with the motor when the motor is running slow. When running fast, the
resistor is in circuit to slow it down. It oscillates between these two
conditions. The motor speed could be varied with a triac in series
(classic incandescent lamp dimmer) with a tachometer (probably a
reflective opto sensor sensing a spot on the fan) generating the speed
sample.

Harold
https://w6iwi.org


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