My breadboard rig

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19-05-2020, 07:19 PM
jugglindan

1 Attachment(s)

My breadboard rig

For no apparent reason, here is a photo of my breadboard rig for playing with pedal circuits:
Attachment 35215

I was going to use an actual wooden breadboard, but they ain't cheap (well, OK, they are but I can get a lot of components for $8) so I used a ratty lump of wood I had previously been using as support for drilling holes in things. The bracket has been drilled to accept jacks, pots, and switches as needed.

The ratty wood is sort of appropriate, as this is a ProCo Rat I am building to experiment with while I relearn some basic analog electronics. Power stage is top-left, signal input and initial filtering top-right, gain stage is bottom-right, into the middle clipping diodes, then tone filter (called "filter" and wired backwards on the Rat) at the front to the left of clipping diodes. I haven't added the JFET output buffer and volume control yet, but the circuit is playable taking the output of the tone circuit direct to the output jack.

It's also the wrong op amp. I only have 4558s, everything else seems permanently stuck in the post right now. From what I have read, this could make my rat a little harsher as the original op amp tends not to amplify the higher harmonics as much. I don't have anything to compare with though, and it sounds ratty to me.
19-05-2020, 07:38 PM
Joe Garfield

I love this. I’d really like to know more about audio electronics (power supplies, amplification, filters, etc) and these posts are inspiring me to get started. If my compressor comes out OK I think I’ll build a breadboard and experiment with different types of gain. I’m starting to amass a few spare components now which is nice.

Thank you.
19-05-2020, 07:43 PM
Woltz

Quote:

Originally Posted by jugglindan

For no apparent reason, here is a photo of my breadboard rig for playing with pedal circuits:
Attachment 35215

I was going to use an actual wooden breadboard, but they ain't cheap (well, OK, they are but I can get a lot of components for $8) so I used a ratty lump of wood I had previously been using as support for drilling holes in things. The bracket has been drilled to accept jacks, pots, and switches as needed.

The ratty wood is sort of appropriate, as this is a ProCo Rat I am building to experiment with while I relearn some basic analog electronics. Power stage is top-left, signal input and initial filtering top-right, gain stage is bottom-right, into the middle clipping diodes, then tone filter (called "filter" and wired backwards on the Rat) at the front to the left of clipping diodes. I haven't added the JFET output buffer and volume control yet, but the circuit is playable taking the output of the tone circuit direct to the output jack.

It's also the wrong op amp. I only have 4558s, everything else seems permanently stuck in the post right now. From what I have read, this could make my rat a little harsher as the original op amp tends not to amplify the higher harmonics as much. I don't have anything to compare with though, and it sounds ratty to me.

I've got a spare CA3080 if that's of use to you?

Sent from my SM-G960F using Tapatalk
19-05-2020, 07:53 PM
jugglindan

The Rat is a good one to experiment on, since the circuit is relatively simple, well understood and documented, and it has lots of modding potential. If you want to start exploring this world, here are a few resources I have found invaluable as I relearn what I used to know 30 years ago (when I was studying electrical engineering):
Jack Orman's website He has a range of reasonably priced ebooks on what makes pedals tick as well as lots of information freely given.

Electrosmash. More good info, including a full breakdown of some classic circuits, including the Rat (I am building from their schematic since it is so clearly done).

Elliot Sound Products have a lot of info, including a beginners section covering basic components and onwards.

And of course, freestompboxes.org. A massive community and a wealth of information. Oddly though I have never posted there, but I lurk a lot.
19-05-2020, 08:07 PM
jugglindan

Quote:

Originally Posted by Woltz

I've got a spare CA3080 if that's of use to you?

Sent from my SM-G960F using Tapatalk

Thanks, but that's OK. I have some TL072s, LM386s, LM741s, & LM308s on order (as well as Ge diodes, the correct JFETs for the Phase 45, and other parts). I am just building this Rat for tinkering, and any old op amp will do the job for that. By the time I discover which mods I like and go to build on on stripboard I am sure the 308s will have arrived. At which point I will probably discover that I like something else anyway :)

It would be good to catch up with some Canberra builders and share stories once this whole COVID-19 shutdown starts relaxing a bit more.
29-05-2020, 01:06 PM
DrNomis_44

I'm going to be getting-together a breadboard and small +/- 15V variable power supply so I can do some more work on building the modules which will be included in my diy modular synthesizer build, there's going to be at least 44 modules including a Tube/Valve VCA (Voltage Controlled Amplifier), and a 16-Step analog sequencer with vari-clock, there's going to be a total of 8 VCOs (Voltage Controlled Oscillators) that will put-out Sine, Square, Triangle, and Sawtooth waveforms, as well as a noise source, I've already got the Tube VCA module built, but un-tested so I'm not sure if it actually works.

I'm also going to be including a few VCF (Voltage Controlled Filter) modules too, the whole audio signal-path is going to be 100% analog, but there will be some digital circuitry included, like for example a DSP FX module, and a Midi to CV (Control Voltage) converter, I'm also going to be including a small oscilloscope display module, for looking at signals.
29-05-2020, 02:14 PM
jugglindan

Quote:

Originally Posted by DrNomis_44

I'm going to be getting-together a breadboard and small +/- 15V variable power supply so I can do some more work on building the modules which will be included in my diy modular synthesizer build, there's going to be at least 44 modules including a Tube/Valve VCA (Voltage Controlled Amplifier), and a 16-Step analog sequencer with vari-clock, there's going to be a total of 8 VCOs (Voltage Controlled Oscillators) that will put-out Sine, Square, Triangle, and Sawtooth waveforms, as well as a noise source, I've already got the Tube VCA module built, but un-tested so I'm not sure if it actually works.

I'm also going to be including a few VCF (Voltage Controlled Filter) modules too, the whole audio signal-path is going to be 100% analog, but there will be some digital circuitry included, like for example a DSP FX module, and a Midi to CV (Control Voltage) converter, I'm also going to be including a small oscilloscope display module, for looking at signals.

Your setup sounds a lot more sophisticated than mine. My only diagnostic tool is a DMM from Jaycar. I have built 4 pedals so far this year, but I am really only just getting into this hobby, trying to relearn some of what I knew when studying electrical engineering (before dropping out) 30+ years ago.

An oscilloscope and an adjustable oscillator for driving the input would be invaluable for testing, tweaking and debugging audio circuits though. I am quite green with envy!

DC
29-05-2020, 02:40 PM
DrNomis_44

Quote:

Originally Posted by jugglindan

Your setup sounds a lot more sophisticated than mine. My only diagnostic tool is a DMM from Jaycar. I have built 4 pedals so far this year, but I am really only just getting into this hobby, trying to relearn some of what I knew when studying electrical engineering (before dropping out) 30+ years ago.

An oscilloscope and an adjustable oscillator for driving the input would be invaluable for testing, tweaking and debugging audio circuits though. I am quite green with envy!

DC

Yep, I do happen to have an old Dick Smith Electronics 20Mhz dual-trace oscilloscope, which I bought back in 1998 or so, got an even older Telequipment Scope in a cupboard in my studio room, it needs a bit of restoration work done on it and a replacement CRT to get it working, I do need to build a good audio Sine/Square wave generator too.

I've got the basic design for my breadboard power supply worked-out in my head, just need to buy all the bits and pieces to build it and then I'll be able to get cracking with the modular synthesizer build.

Also need to buy two new scope probes and a good logic probe for de-bugging digital circuits, digital electronics isn't really my forte, analog electronics is what I'm better at than digital, although I know some digital electronics theory.

If you have a look on eBay, you might be able to pick up a decent 5MHz or 10MHz single-trace oscilloscope for maybe $200 or so, those are fine for audio testing/debugging work, make sure it's rated to work on our Australian 240V AC mains though.
15-06-2020, 12:17 PM
DrNomis_44

I'm going to be buying a couple of new 10:1 100Mhz Oscilloscope probes for my old DSE Q-1804 20Mhz Dual-Trace Scope from Jaycar Electronics tomorrow.
15-06-2020, 01:51 PM
jugglindan

Sounds cool. I have decided to build one of these. It's a very simple signal injector and audio probe on a single board. Not as handy as a scope, but still useful. I just need to check some datasheets to see which transistor I can sub. I don't have any BC547s on hand. I do have some other NPN small signal transistors (S8050 and others) that should work. Maybe breadboarding and some suck it and see engineering will be faster than reading datasheets :)
16-06-2020, 02:20 AM
DrNomis_44

Quote:

Originally Posted by jugglindan

Sounds cool. I have decided to build one of these. It's a very simple signal injector and audio probe on a single board. Not as handy as a scope, but still useful. I just need to check some datasheets to see which transistor I can sub. I don't have any BC547s on hand. I do have some other NPN small signal transistors (S8050 and others) that should work. Maybe breadboarding and some suck it and see engineering will be faster than reading datasheets :)

You could substitute a BC548, BC549, or even a 2N3904 or 2N2222 (might have a different pinout though), for the BC547, and they should all work fine, since they are all NPN types.

A BC107, BC108, or BC109, should also work fine as a substitute for a BC547.

I just checked-out the link you posted and I think that's a great little bit of test gear, looks easy enough to build.
16-06-2020, 02:22 PM
DrNomis_44

Just got my two new 10:1 100Mhz Scope probes home from the shops, I also bought a new 2m IEC lead for my scope while I was at it.

I'm wondering if anyone would be interested in me doing a mini-tutorial on Oscilloscopes and how to use them?
16-06-2020, 02:28 PM
JohnH

Quote:

Originally Posted by DrNomis_44

I'm wondering if anyone would be interested in me doing a mini-tutorial on Oscilloscopes and how to use them?

Yes! That'd be great
16-06-2020, 02:42 PM
DrNomis_44

Quote:

Originally Posted by JohnH

Yes! That'd be great

No worries, I'll start a new thread about it in the DIY Pedals section then, I'm going to be using my 20Mhz Dual-Trace scope for demonstration purposes in the new thread, which will include some screenshots.