Pictured is a Digitech PDS 1002 delay pedal modified with a control voltage input for delay time (via the 1/8” jack in the picture). The mod uses a homemade vactrol. With the delay time knob fully counter clockwise the CV input has no effect. As you turn up the knob the external CV begins to affect the delay time.
In this clip the delay time is being modified by my Wiard Noisering synth module (Random Voltage/Sequencer). The sound source is a squarewave drone. All of the pitch changes are done via CV control of the delay time.
Almost any piece of equipment can be modified with this type of CV control. If you’re interested in adding CV inputs to something of yours, shoot me an email.