Echo-Matic! Breakout Box Tape Delay

Proto-Schlock DIY box for using a cassette player/recorder as a tape delay

This surprisingly simple circuit turns any 3 head tape recorder into an awesome sounding tape delay machine. The tape recorder has to be a three head unit (erase head, record head, and play head) for it to work. This type of recorder will have a button or switch that allows you to listen to the source audio, or what has just been recorded to the tape. The small gap between the record head and the play head creates the delay effect. I'm a novice when it comes to circuit design, but the schematic just looks like four buffers and some pots to mix the different signals together.

http://proto-schlock.blogspot.com/2015/04/echo-matic-diy-tape-delay.html#:~:text=This%20knob%20adjusts%20the%20pitch,head)%20for%20it%20to%20work.