Control a servo (180-degree swing) with an On/Off switch without arduino (?)

Hi,

For my application, I need to be able to control a servo with a simple on/off switch. When it’s off (pulled LOW), I need to servo to go at -90 degrees and stay there – possibly for a prolonged time. When it’s on (pulled HIGH), I need the servo to go to +90 degree and stay there – possibly for a prolonged time.

I’d like to minimize the control logic footprint and complexity, and also to minimize standby power consumption in servo jitter in both positions. So ideally I’d want to get by without Arduino at all – with some kind of a simple analog / IC logic based on servo’s internal potentiometer, and direct control of motor wires.

Rotation precision is not important, so +90 can be “anything above +85 degrees”, and -90 can be “anything below -85 degrees”.

I won’t be able to fit external end-switches to the mechanical application and want to rely on servo’s internals only. I have a bunch of no-name SG90 lying around (which are a perfect fit size-wise and torque-wise) – but I would not be against buying a different kind of a “servo-like” actuator that would facilitate a simpler conversion.

Can someone suggest where to look for the solution schematics – and whether it might exist as a pre-made IC?

Update: found a https://www.sparkfun.com/products/13118?_ga=2.160099069.1169016740.1587923297-1103320110.1587923297 – Servo Trigger board, which at a first glance does what I need. While it is easy to use, it is still an over-complicated (internally) solution with a constantly running microcontroller to produce PWM pulses that are to be decoded on the servo side.

I guess a much simpler (and less idle power draw) solution would be possible based on a direct hook-up to servo’s potentiometer and analog comparator logic.

Thanks!

submitted by /u/spgremlin
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