David researched and found a digital potentiometer by Intersil (X9511WP)-it arrived today. It’s a 10K ohm device with 32 up/down steps controlled by the three button array David salvaged from a printer (seen on the left). It works flawlessly with about 330 ohms per step. This device is limited to a wiper current of only 1ma. I also connected it to a 555 timer in an astable configuration. By replacing the two timing resistors with the digital pot, we can vary the ratio of the two resistors. The duty cycle is determined by this ratio giving good motor speed control via a mosfet. It works great and we think it is a better solution for control of the dive motor speed over a continuous mechanical potentiometer.
