Here is a more detailed image of the circuit:

the values of the resistors and the capacitor depend on the input signal wave shape and voltage.

Important! Use optical isolation between the output of the circuit and the tap tempo input of the JamMan.

I’ve used the following values:

Opto-C = LTV827
R0 = 180 Ohm
R1 = 10K
R2 = 4.7K
D1 Diode (reverse voltage protection) = 1N4007
Diode = 1N4148
Cap = 22µF
and 3 Schmitt trigger gates

The following are scope shots of input, output waves and samples from other points in the circuit:

Sample1 is the output of the metronome. As you can see it’s an AC square wave.

and zoomed in:

and scope shots of samples from other points in the circuit:

and here is the output signal:

input and output superimposed: