Feedback Looper Project

The Feedback Looper

The circuit constructed creates a feedback loop in which the original signal is produced and flows through the circuit. The output is then ran back into the input and this process repeats creating what is known as a feedback loop. Feedback has many practical applications in electronics most notably increasing gain in a circuit.

Purpose and Goals

1.) The primary goal of this project is to successfully design a pedal capable of housing its circuit.

2.) Become familiar with components such as 3pdt switches, mono audio jacks, and DC power jacks.

3.) Produce a pedal for less than the average market value.

Feedback loopers generally go for about $50-$100 when bought new. The sabo-tabby feedback looper pedal shown is a very similar circuit and has the same main functionality as the circuit being designed in this project.

Materials/ Components

Mono audio jack x4 $3.48
Pedal enclosure $26.90
DC power jack $0.13
3pdt switch $2.49
500k linear potentiometer $0.50
LED $0.02
Knob $0.50
Wires $0.94
Resistor $0.01

Total: $34.97

3PDT Switch

(Three pull double throw switch)

The image above shows the pinout for a 3pdt switch and although this is not the only way to wire it, this is the wiring that will be used for this project.

DC Power Jack

The pedal being constructed for this project does not include a 9 volt battery, so both positive nodes of the DC jack will be soldered together.

Mono Audio Jack

Four mono audio jacks will be used as an in, out, send, and return jack. All of the negative sleeves will be soldered together as that is the ground.

Circuit Schematic

Shown in the picture is the pedal schematic provided by Holy Island Audio. This is the schematic that was referenced when wiring the circuit. The circuit itself is relatively simple, only requiring a resistor and LED which is in place to signal when the effect is turned on and off. The audio jacks are labeled as follows; in, out, send, and receive. The "in" jack is the input of the guitar signal, this is where the cable from the guitar gets plugged in. The "out" jack is where the pedal would then be connected to a guitar amp or something equivalent. The send and return jacks are what allow the signal to be modified. These jacks allow the user to send a certain amount of signal to another effect pedal or black box circuit which will modify the signal in some sort of way, ex. modulation, distortion, filters, etc. This signal is fed back over and over again creating some interesting sounds. The amount of signal that is sent can be controlled by the linear potentiometer that varies from 0-500K ohms. This effectively controls and limits the current entering the send jack.

Completed wiring and souldering of circuit

Exterior and enclosure of pedal