Digital Trim Pot with LED Display



  • On-board 8-bit microcontroller
  • Eight (8) LEDs, staged in colour: four green; three yellow; one red.
  • Any normally-open momentary switch can be used.
  • 0.5-4.5V linear output
  • 5V supply
  • Non-volatile option available (default mode sets outputs to minimum voltage on reset).
  • Resettable fuse protection on power and return signal lines. Voltages to 24V tolerable.


The digital trim-pot (digpot) is a response to a need by joystick manufacturers to add thumb-operated proportional controls to their products. Buttons mounted on top of the joystick can be used to provide a variable signal, while providing operator feedback in the form of a LED bar showing real-time signal level. Unreliable potentiometers can be replaced with simple momentary switches for a more robust system.
The output follows an acceleration curve when one of the buttons is initially pressed. Initial response will be slow permitting fine-control of output devices; however, after aproximately 500mS the output will change much more rapidly.
The below diagrams are sampled data of a production unit showing the transition from minimum output voltage to maximum and back to minimum.

  • ΔV = 4.60V
  • Δt = 2.66S
  • Vmin = 240mV
  • Vmax = 4.82V
  • 1V/div
  • 400mS/div
  • ΔV = 4.58V
  • Δt = 2.68S
  • Vmin = 240mV
  • Vmax = 4.82V
  • 1V/div
  • 400mS/div