I have a fairly simple project coming up. My task is to design a system which powers and controls a Pan and Tilt positioner for a camera. It has some weird and unavoidable requirements/constraints:
- No telemetry allowed in the Pan and Tilt positioner. Power must go straight from a control box, through a wire, directly to motors.
- PWM or AC should be avoided. The Pan and Tilt conductors will have to be in the same Minikevlar cable assembly as some low-voltage analog signals, and PWM would likely be too noisy.
- As the title suggests, speed control is not a requirement.
The Pan and Tilt will likely contain 24V brushed motors for both axes. My initial approach would be to use a switch joystick to open/close a circuit for each motor in forward and reverse, and supply it via a 24V+ DC power supply (I say 24V+ because I will be accounting for Vdrop). I would also need a current limiting device of some sort to protect the motor when it reaches end-stops.
My second idea would be to use PWM anyway, and if it causes interference in the sensitive low voltage signals in the cable, I could keep changing the PWM frequency until I find something that works (while driving the motor properly, of course). However, if I keep the PWM duty cycle at 100%, I feel like it defeats the purpose.
What are your thoughts, and how would you approach this? I'm assuming my solutions are missing something important because my experience with electronics is not quite as extensive as I want it to be.