What is it?

This module implements unity gain input and output buffers for breadboard prototyping of guitar audio circuits. The input and output are ¼" jacks. There is also a toggle switch to bypass the buffers and connect the input directly to the output.

Why did you make it?

The goal for this module was to implement all the general I/O circuitry that is required when prototyping a guitar effect or similar analogue circuit on breadboard in a single small module. For me at least that means:

• Breaking out ¼" jacks for input and output (these do not usually fit into breadboards without a fight)
• Buffering the input signal so that the signal source isn't loaded (this can introduce unwanted low-pass filtering or more unpredictable but equally undesirable effects)
• Buffering the output signal so that the circuit under development isn't loaded
• Providing a bypass switch so that the circuit that is being developed can be switched in and out of the signal path easily

This module implements all of these features. As a bonus, because of the switching contacts built into standard jacks the input signal can automatically switch between two sources. When there is no plug in the input jack the input is instead taken from Pin 16 (Sig-gen+), when there is a plug in the input jack Pin 16 is disconnected and the input is taken from this plug.

What makes it special?

Implementing a breakout for two ¼" jacks with a bypass switch and two buffers would normally take up much more breadboard space. This module implements all of these features in only slightly more board area than a single jack and a toggle switch.

How to use it?

The module requires a bipolar power supply. The details of the supply range and pin-out can be found by following the Documentation link below but typically +4.5 V, 0 V, and -4.5 V would be required on the V+, Vref and V- pins respectively. The module includes power supply decoupling so external decoupling capacitors should not be required.