Building a Clean Boost Guitar Pedal

First delivered to my Music Production undergraduate students during lockdown, here I talk through the process of designing and prototyping a clean booster for guitar.

00:00 Introduction
02:02 Powering the Circuit
02:55 Measuring Battery Voltage
05:18 Operational Amplifier or Op Amp
09:04 Using a Potential Divider to power the circuit
16:09 Input Impedance
17:12 DC Blocking Capacitors
18:32 How the Op Amp functions in this circuit
19:58 The Maths (Gain)
23:20 Breadboarding the Circuit
34:48 Mistakes were made!
38:26 Testing with a Sawtooth
41:00 Using the Oscilloscope to Measure the Gain
43:44 Testing with Guitar

I am no expert in electronics, I remain a curious hobbyist. However, I have always been fascinated in learning how audio electronics works. Disassembling various radios as a kid and eventually becoming interested in designing and building guitar effects pedals. I attempt to understand how these systems operate electronically, and due to this approach, I have picked up a few bits of theory along the way. If you're unsure about it, my best advice is just get started, mistakes and corrections (and the occasionally popped component) is how we learn. You win or you learn

In this video I do my best to explain the simple Op Amp based booster circuit, build it on the breadboard and then test the prototype, using a mixture of my own DIY Lab test equipment, and a Digital Oscilloscope.

If you found this useful, want to correct my knowledge or want to know more about my DIY pedals and test gear leave a comment below.

Follow my other projects here:

[martinlewis]

Have been using pedals for 50 years! And now decided that I ought to understand them properly and your input is really appreciated. Got my first pedal kit, random parts and breadboard on order, so looking forward to diving in. No doubt will be referring back to your video(s) - just the right balance of theoretical and practical - many thanks.

[ae-tmdg]

I'm making a pedal for my GCSE engineering project and this was very helpful

[MyNameWasTecho]

Only 10 minutes in and loving the clear, thorough explanation. Not often I’ll subscribe before finishing a video, but this is one of those rare occasions. 👍

[DustinKreidler]

Excellent discussion of the why's for each of the components. I've been getting into design/build videos, and your discussion puts a lot of the ones I've already watched into a new perspective, especially the bias circuit. Cheers!

[emanuelmandarinifalero]

The best tutorial to learn audio electronics. please continue with the work of education. thank you

[poorbadger]

Coming from someone who used to know all this but hasn’t thought about it in a decade or more - excellent clear and thoughtful explanations at a good pace. Thank you!

[neilsmith]

How did I only just find this channel?! I’ve played guitar for 30+years and tinkered with electronics on and off, but really want to get into making my own tones and sounds.

Thanks to this channel I just ordered a breadboard and component set.

I can well appreciate how much effort and thought goes into these vids, but please know you have a fantastic teaching style. The pace is perfect, the context helpful, the leaving in mistakes and among questions along the way - super helpful.

Please do more!

I am really interested in the filtering aspects at the moment. Both for within a circuit but also to create a customs EQ circuit 😊

Thanks for your contribution to the pedal and electronics community and here’s to more content. 💥💥💥

[BrunoEspadanaGuitar]

This was perfect for someone like me who only recently started learning about guitar pedal electronics. Clearly explained and easy to follow - thank you!

[ms]

This is an absolutely amazing lesson! This is the very first video I see in which I finally understand how translating an schematic to a protoboard works. Please keep making these type of videos!

[rogerw]

I have a breadboard you can trouble shoot that I just built, lol. Great videos, awesome explanation, so many thanks

[densmalavagenskapell]

Finnaly an explanation that even I could understand. Nice and simpel. Will be watching moore of your uploads in the future. Thumbs up!

[carlosixty]

Great video easy to understand the foundamental bases of analog electronics

[til]

Brilliant Tutorial. Very well explained. Thank you very much.

[albouyhadrien]

Thank you for helping me understand what the Bias voltage is !

[TheseDazeAudio]

You explain perfectly; I finally understood. Thanks a lot!

[martinrauch]

Amazing Lesson. Really good job explaining everything step by step. I still have one question. You explained nicely the purpose of the 100 nF at the start of the circuit, but what purpose do the 10 uF capacitors serve for both the output and the other potential divider?

[kevinarbogast]

I’m starting to understand breadboards but I’m having trouble understanding how to transfer them to a strip board for permanent small build. A video transferring this circuit to a stripboard would be very helpful! Thanks for your videos!

[iblesbosuok]

I suggest:
1. It is better to add a 0.1uF-1uF capacitor to the LM741 supply rail. Capacitor's pins connected as close as possible to pin 4 and pin 7 of LM741. The addition of a capacitor will solidify the output sound.
2. You can replace R1 to 12k and replace R2 to 47k. Reducing the value of R2 will reduce the noise. Gain will increase to about 5 volts/volts.
3. It is better to apply a 100-470 ohm resistor in series with the 10uF output electrolytic capacitor to ensure that the LM741 is stable.
4. It is better to try another several types of IC to replace the LM741. I suggest trial with CA3130, CA3140, LF351, LF355, LF356, LF357, LM301, LM318, NE5534, TL071 etc to get a sound personality that suits your art personality.

I'm a technician and I can't live without art.
Thank you

[hzzle]

Trying to give into schematics and understanding currents after building pedals for about 5 years (not my PCBs). Your videos are very helpful and easy to watch. I was wondering if you could help clarify what reason to use which resistor values when dividing voltage? For example why is 2m2 used, instead of 1m, or any other? I’m sure you covered this but am still trying to understand. Cheers!

[fraxz]

This is great! I'd like to see some more of your creations on breadboard. Thanks for the nice info!