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Signal pathDrag a knob. Add a block.
IN
DRIVE
GAIN
BIAS
LEVEL
MODULATION
RATE
DEPTH
DELAY
TIME
FEEDBACK
MIX
OUT
0 MS1600 MS

SIGSignal pathAn input wave through a rack of the same five stages these builds use, each block's own output is traced live as its knobs turn. Most of what a delay or a filter actually does only shows on the note.

Building Guitar Pedals

Personal project · Atlanta, GA

Role
Everything
Group
Georgia Tech Invention Studio and HIVE makerspace
Location
Atlanta, GA
Dates
August – December 2025

I built two analog guitar pedals by hand, a discrete delay and modulation unit inspired by the Echo Dream 2, and a four-track-style clipping fuzz based on a Demo Tape Fuzz.

I populated the boards, drilled and finished the enclosures, wired the switches and jacks, and tested the finished circuits. When something didn't work, it sent me down a rabbit hole to figure out why, as it was most likely something that I had done wrong.

I built with what I had on hand, often times straying from the original design. Parts came from bins, salvage, and eBay lots as often as from a distributor. The result isn't quite the original design. It is its own circuit, with some of those compromises showing up in a unique new sound.

Background

Building guitar pedals is really a simple exercise in analog electronics. A fun project that can be done in an hour or two (if you know what you are doing) and the whole thing fits on a basic workbench. I can populate the board, drill the box, wire the switch, turn a trim pot, and, a few hours later, find out whether I made a fuzz or an expensive little box of silence. There aren't many things I work on where I get to be responsible for every part of the machine and then immediately use it.

Georgia Tech also happened to have the perfect places to do it. The Invention Studio and the HIVE had most of what I needed already sitting on the benches: soldering irons, drill presses, oscilloscopes, component drawers, and all the other accumulated stuff that makes a shop useful. All I needed was a circuit, some parts, and an afternoon.

A makerspace bench: a pegboard of hand tools above, a soldering iron in its stand, two helping-hands arms holding wires, a yellow drilled enclosure blank, and the pedal's perfboard lying on the bench with loose potentiometers and switches wired to it.
02Work BenchWhere the magic happens.

Sourcing Components

I sourced parts the way you eyeball a recipe. If the build called for a value I didn't have, I reached into the drawer for something close given it was reasonably within the range of the original part. Capacitors came off salvaged boards. Switches and potentiometers came out of miscellaneous bins. ICs arrived in eBay lots with no particular pedigree.

It's not the proper way you build from a bill of materials, but it turned out to be part of the fun. A different capacitor can move the corner of a filter. A different pair of diodes can change the shape of the clipping.

The Demo Tape Fuzz with its back off, seen from above on a wooden bench. Four potentiometers, their shafts labelled B100K, B20K and A10K, wire in white, blue, yellow, orange and grey to a rectangle of perfboard carrying resistors, film and electrolytic capacitors, and a trimmer.
03Demo Tape Fuzz, insideThe fuzz's harness is simpler than the delay's, but the board is more densely populated.
A stripboard layout diagram for the Mid-Fi Electronics Demo Tape Fuzz: component footprints and values placed on an 18-by-10 orange stripboard, wired out to labelled treble, bass, volume, and trim controls, with a smaller board below marked 4 links and 14 cuts.
04Demo Tape Fuzz, layoutThe build document itself, from tagboardeffects.com.
A stripboard layout diagram for the Death By Audio Echo Dream 2: two orange stripboard sections, the left dense with component footprints and values for the feedback, blend, master, fuzz, and time controls, the right mostly bare jumper wire, above a note reading 30 by 21, 63 cuts, 22 links.
05Echo Dream 2, layoutThe build document this one followed, from tagboardeffects.com. Note power input calls for +9V and +18V DC. This build used a second power board with a 7805 regulator to make the second rail.

Assembly

The build order: populate the board, wire the hardware, then put everything into the enclosure. I spent a lot of afternoons at the Invention Studio with a soldering iron in one hand and the schematic in the other, working pad by pad and checking each connection before moving on, usually until the shop closed.

Fabricating the enclosure was a different type of fun. Drilling holes in the cast aluminum enclosure, finishing the box, mounting the jacks, footswitch, and pots, then somehow squeezing all the wiring into the small amount of space left over.

The Echo Dream 2 open on a bench, enclosure on its side with the board outside it. A dense perfboard of electrolytic capacitors, resistors and DIP integrated circuits connects by a spray of coloured wire to potentiometers, toggle switches and jacks. A green and a red indicator LED are lit, and a probe with a red clip is attached to the board.
06Gut shot, powered upThe board is out of the box here and running, with a probe on it to measure power and signal.

Bench test

I always check the power supply rails and grounds before feeding anything into the circuit, then worked through the signal path one stage at a time. A multimeter and the op-amp pinouts were usually enough to find the point where the circuit stopped doing what it was supposed to.

A lot of that time went into bad ICs. Buying old sometimes discontinued op-amps online means some fraction of them are dead, mislabelled, or counterfeit.Other issues were at solder connections. Cold joints, a bridged pad, a lead pulled off during assembly.

A Keysight InfiniiVision DSOX4024A oscilloscope screen showing five cycles of a green sine wave at 200 mV per division and 20 ms per division. The measurement panel reads AC RMS Cyc(2) 162.87 mV, with no signal on channel 1.
07Signal on the benchTroubleshooting the pedal on a scope. Reading a stage's output is faster than guessing which stage is wrong.

Echo Dream 2, delay and modulation

The Echo Dream 2 is a discrete analog delay with an added modulation and drive stage in the signal path. The repeats get softer, dirtier, and a little less predictable each time it goes around. Feedback takes part of the delayed signal and sends it back through the circuit, turning one repeat into a trail of repeats and, with enough of it, into self-oscillation. The dry path runs around the wet section, so the original note stays underneath all of this. That distinction is easier to see in the diagram below.

The schematic gets down to the parts level. This is the version I used to build the stripboard, and the block diagram above is what that much messier drawing looks like when you zoom back out.

Block diagram. Guitar in feeds an input buffer, then a drive and fuzz stage, then a delay line with filtering, then a dry/wet mix to the amp out. A modulation LFO feeds the delay line. A tap from the delay output returns to a feedback block that feeds the drive stage. A dry path runs from the buffer directly to the mix.
08Echo Dream 2 signal pathStage-level block diagram. Modulation moves the delay line, feedback returns the repeats to the drive stage, and the dry path keeps the original note intact underneath the effect.
A hand-drawn schematic of the Death By Audio Echo Dream 2: an MC33172P op-amp stage feeding a PT2399 delay chip and a 2260P vibrato chip, with potentiometers labelled fuzz, master, blend, speed, depth, feedback, and delay time, a 7805 voltage regulator, and switch and LED wiring, titled Echo Dream 2 Rev 2.
09Echo Dream 2, reference schematicThe PT2399 is for the delay line and the 2260P the modulation. Everything else is for the bias, filtering, and controls.

Demo Tape Fuzz, clipping

The Demo Tape Fuzz combines a gain stage, a clipping section, then tone and level controls. The gain stage bias is adjustable, and where that bias sits changes the behavior of the pedal. Small adjustment in the gain is where a lot of the pedal's personality lives.

The clipping diodes are the other key part. Their set when the signal starts to clip, while the pair determines how evenly it clips in each direction.

Block diagram. Guitar in feeds an input stage, then a gain stage marked bias and drive, then a clipping section, then a tone and level stage to the amp out. Below the clipping section, a pair of back-to-back diodes to ground.
10Demo Tape Fuzz signal pathStage-level block diagram. The bias on the gain stage and the diodes in the clipping pair are what give the pedal its characteristic sound.

Shout Out

Special thanks to Georgia Tech's Invention Studio and the HIVE makerspace for facilitating these builds. Go Jackets.

Skills applied

Electronics
  • Perfboard and PCB assembly
  • Offboard wiring and harness assembly
  • IC socketing and testing
  • Desoldering
Bench and test
  • Supply rail and ground verification
  • Signal tracing
  • Continuity and voltage measurement
  • Op-amp pinout and test-point verification
  • Fault isolation
Circuits
  • Reading schematics
  • Diode selection
  • Passive filter and tone stacks
Fabrication
  • Enclosure layout and drilling
  • Enclosure finishing
  • Component sourcing

Sources