Square Wave Guitar Pedal

[Legal_Planet]

I'll jump to the case to avoid wasting too much of the readers' time.  But I'll note I've done some rather hideous armature circuits to attempt this before asking people who're far more experienced.

So the question is what'd be the best way to achieve a square wave from a guitar signal? 
I'd measure the voltage from the pickups but have no tools to do so.  But the internet gods are saying 35mV to 1v is average.  So I'm thinking boosting the voltage and using an op-amp (in my case a LM324) as a comparator would somehow work?  I've tried to do so with no luck.  But again I'm quite the nooby here.

[Wimberleytech]

I've tried to do so with no luck.  But again I'm quite the nooby here.

You probably did not bias and ac couple it correctly.  Search "op amp guitar preamp schematic" and there are many ideas to choose from.  Take the output of the preamp and drive into another 324 properly biased acting as a comparator.

[Legal_Planet]

Thanks!  Will give a look and a try.

[Zero999]

Why not use a proper IC designed to  be a comparator, such as the LM393 or LM339? The LM324 is designed to be a linear amplifier, not a comparator. It can be used as a comparator but very poorly, compared to a proper comparator IC.

[Dumpsterholic]

Craig Anderton's book is a little dated. but inside it you'll find a couple of fuzz circuits which sound pretty good with electric guitars. If I remember correctly, he has a circuit built around a CD4049 hex inverter that'll give you a nasty square-wave sound.

https://www.barnesandnoble.com/p/electronic-projects-for-musicians-with-soundsheet-craig-anderton/1000130023/2679416112164?st=PLA&sid=BNB_DRS_New+Marketplace+Shopping+Textbooks_00000000&2sid=Google_&sourceId=PLGoP164984&gclid=EAIaIQobChMI6u_azKHy2QIVTLnACh0TAAgsEAQYASABEgL8RPD_BwE

[Audioguru]

A raspy squarewave sounds awful on good speakers by a person having good hearing. It sounds fine on a cheap guitar speaker that has bad high frequency response by a person who is deaf.
I turn off my hearing aids when I hear electric guitar fuzz or bagpipes.

[Wimberleytech]

A raspy squarewave sounds awful on good speakers by a person having good hearing. It sounds fine on a cheap guitar speaker that has bad high frequency response by a person who is deaf.
I turn off my hearing aids when I hear electric guitar fuzz or bagpipes.

Well...it is Friday night.

[Legal_Planet]

I found a pdf of the book online and have been reading through it from start for the past 30 minutes.  Wanted to stop real quick to say thanks and that it's a perfect starting place.  And the square wave isn't meant to be ear candy but rather a building block.  No plans to destroy people's ears or my own!

[Bassman59]

A raspy squarewave sounds awful on good speakers by a person having good hearing. It sounds fine on a cheap guitar speaker that has bad high frequency response by a person who is deaf.

An electric guitar tone necessarily involves the speakers in the cabinet and especially the low-pass response of those speakers. It’s all part of the signal chain.

A Rat fuzztone into a direct box into a mic preamp sounds awful. Into my ‘62 Bandmaster which drives a 2x12” cabinet, it sounds pretty great.

[Bassman59]

I'll jump to the case to avoid wasting too much of the readers' time.  But I'll note I've done some rather hideous armature circuits to attempt this before asking people who're far more experienced.

So the question is what'd be the best way to achieve a square wave from a guitar signal? 
I'd measure the voltage from the pickups but have no tools to do so.  But the internet gods are saying 35mV to 1v is average.  So I'm thinking boosting the voltage and using an op-amp (in my case a LM324) as a comparator would somehow work?  I've tried to do so with no luck.  But again I'm quite the nooby here.

Don’t use a comparator. An op-amp with back-to-back diodes in the feedback loop is a good starting point. See here, for example.

[mgraves235]

a purely square wave audio signal will sound horrible, plus running DC current into a speaker is a great way to destroy it.

[iampoor]

Guitar square waves sound pretty good. Good in a "raw" sort of way (Yeah its an acquired taste!). Depends on the effect. I like Tim Escobedos square wave shaper, but its pretty intense!

http://www.diale.org/escobedo.html

A raspy squarewave sounds awful on good speakers by a person having good hearing. It sounds fine on a cheap guitar speaker that has bad high frequency response by a person who is deaf.
I turn off my hearing aids when I hear electric guitar fuzz or bagpipes.

Most guitar speakers roll off past 7khz...many GOOD amps do too. Sounds like you just dont like fuzz tones. Reasonable enough.

a purely square wave audio signal will sound horrible, plus running DC current into a speaker is a great way to destroy it.

Except it is a common effect....A "Fuzz box" basically is a square wave generator, and sounds far from horrible. We have beenusing them for a good 50 years now. :-)

[Nerull]

Square waves were common in synths for a while too.

The NES sound chip's two primary channels are square waves, as was the 8-bit Atari line.