The Practice Play Along is used to mix the audio output of a musical instrument with a stereo hi-fi audio system using the stereo system's monitor jacks.
The Practice Play Along is a Craig Anderton design from his "Electronics Projects for Musicians" book. It has a musical instrument input jack and left and right volume controls that affect only the instrument input volume level.
I power the unit with an old Jerome PIDH-36 power adapter that has +12 and -12 volt regulated outputs.
On the back panel there is a potentiometer to adjust the input gain to compensate for the output level of the musical instrument.
This project was the second of two that I made using a Radio Shack printed circuit board making kit. I drew the circuit traces on the board using a permanent marker and etched the board.
I built this project using the TL084 quad op amp in place of the original RC4136 or XC4136 quad op amps that were specified. I had to change the board layout because the TL084 has a different pinout. The RC4136 is still available.