It's about how radio control toy servos from the 1970s work. Annoyingly, those pre-computer dumb devices with no feedback output still dominate the low end of mechanical output devices.
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One of my most amusing applications was the client who put an R/C servo on the choke cable of a carbureted generator motor instead of spending more money to buy the fuel-injected version. Servo cost about $5 and we were already measuring air temperature and had a PWM output available.