2 potentiometer Speed and Max speed governor for sewing machine motor

I was looking to modify a potentiometer driven speed controller for a motor. it runs a 0-5V signal. This is typical for a PWM motor controller while other SCR controllers occasiomally use 0-10V. For the purpose of this exercise i actually designed it with a 10V signal for ease of calculation, but this of course can be changed.I wanted to add a second potentiometer as a maximum speed. *What happens* If the max pot wiper is set to: 10 V, the speed pot outputs 0 to 10 V 5 V, the speed pot outputs 0 to 5 V 1 V, the speed pot outputs 0 to 1 V I wanted the regular speed controller (which is attached to a sewing machine foot pedal) to have a maximum speed but still have it's entire range of motion. i.e.. i didn't want to lower the max speed to 10% voltage and just have the speed potentiometer max out at 10% travel to the end. I want it to be more sensitive and full range. i.e.. if i set it to 50% voltage i want the foot pedal pot to give me 0-50% signal from foot off (full resistance) to pedal down (no resistance full voltage). This is accomplished by wiring two pots. one for speed and a second max potthat modulates the current on one side (hi to lo in this case) feeding the speed potentiometer. This is my first circuit on this platform!

published 1 month ago