Buddy's Breadboard and Circuit Design Notes

[fig]

That's fantastic!

 

[BuddytheReow]

Here’s a little breadboard tidbit I learned today. In my post about Breadboards 101 I mentioned that the power rails marked blue or red go all along the board on both sides. Not all breadboards are like this!

I picked up this breadboard from Tayda and noticed there was no power going from one set of power rails to the other even with a jumper wire going across the board. At first I thought I got a bad board. Lo and behold I noticed that the power rails get cut mid way down the board. You can see that the colored lines are cut showing this as well. Why have this? Off the top of my head you may want to do 2 separate input voltages (9 or 18v). Other than that I have no idea. The simple solution to this “problem” is to simply jumper them. I used solid core wire and it fixed it right up. Now all my breadboards act the same!

 

[BuddytheReow]

Welp, I think I found my limit. I thought my breadboard platform would provide nearly unlimited builds. While this is still true I forgot to figure in user error. My "protoboard" has 3 boards on it and I thought I could work on 3 projects simultaneously. Turns out after 2 things start getting really messy. Especially when I start crossing jumper wires for the various pots. It's always that 3rd build that starts giving me problems.

Not sure if I should post this here or at the Loafing Lounge thread.

Here are 2.5 projects before I called it quits: a MuffRat (schematic below and a nice med/high distortion), my L-PB&J Sandwich, and an attempt at Jack Orman's Son of Screamer. I gave up after the gain stage. Now comes the crappy part of taking it all down

 

[BuddytheReow]

This is more of a rant/complaint than anything else....

First, I'm really enjoying breadboarding. I really enjoy building a circuit from scratch either by following a schematic, modding something, or from the ground up with basic circuit blocks. I haven't really picked up a soldering iron in weeks months now, but I plan on it soon...

I have 2 complaints when it comes to breadboarding:

1. When I'm finished with a breadboard project and happy or not happy with the circuit I have to clean up. Booooooo! Very few of us like cleaning up. Putting all those resistors back in their bags/drawers/compartments, making sure the correct value component goes back where it should, taking the jumper wires out, etc. It's annoying. The solution is to buy more breadboards

2. Where I put circuits together and where I play are on opposite sides of the same room in my basement. I think I've finished a circuit, walk it to the other side of the room, turn on my amp, plug in the guitar, plug in the jumpers on my test box (always on my board now), hit the stomp switch and...nothing. Ok, now I've got to back to my workstation, get my multimeter, get my tablet if a schematic is on there, and go back to my play area to start troubleshooting. Oh, I forgot a jumper cable there? How stupid of me! Back to my workstation for a cable. Yadda yadda yadda... I tend to repeat this process more times than I'd like since I test my circuits in stages (first gain stage, after clipping, after tone control, etc.) to make sure everything works. Maybe you guys are in the same boat too with this even though you're soldering? I would love to have a small amp and cheap guitar at my workstation, but I don't have the room. Correction, I do have the room but the layout of our basement doesn't allow this: our home "gym" is in between.

 

[BuddytheReow]

I've been stalking around Jack Orman's site http://www.muzique.com/ for a while and decided to go through his lab notebook. I chose his Saturation Control page to see how you can change the clipping depth of many circuits that use diode clipping. These are hard clipping circuits, not soft clipping. I would be curious to see how they could be done in, say, an opamp feedback loop but I don't think these ideas here can be transferred part for part. You would be adding resistance to the fb loop and would affect the gain. You can read his article here and all credit for this is to Mr Orman himself.

What's a simple circuit to try this out on? Why, the MXR Dist + of course! I chose to use the schematic taken from Beavis Audio's beavisboard project found here. If you're wondering how to whip this up on a breadboard it shows how to do that as well. Schematic is posted below. For purposes of this experiment I stopped building after C6. A volume pot is not necessary if I'm just experimenting. Plus, I tend to dime most of my dirt pedal volumes anyway. I also modded the circuit a bit too: change C2 to 100n and C4 to 100n. These 2 mods allow a LOT more bass to get through and gives your tone some balls!


Jack's article has 9 variations of the saturation control and I chose to experiment out of order than the article reads. I will label them 1 through 9 if anyone wants to follow along with my notebook/blog here. If there is a capacitor in the examples below right at the input I didn't breadboard them since I've already got an electrolytic already in there (C6). It's merely there as a coupling capacitor (I may write up something about capacitors soon).

First up is example 1. This is the basic saturation control.

I used 1n4148 diodes since they are the "standard" clipping diode IMO. When turned ccw there should be less resistance going to the diodes from the input signal and it should sound harsher per his article. When I tried this out it was VERY subtle turning the pot in either direction, but it is there. Even tweaking the gain pot of the Dist +didn't change the clipping sound that much. The sound is still very usable though. Oh, I should also mention if you've got the gain pot maxed out there will be clipping BEFORE the saturation control. This clipping happens in the opamp itself.

I then tried example 2.

Still using the 1n4148s, this is almost identical to the first example with the exception being that you're controlling only 1 of the diodes. I found this one to be a little less subtle that the first example, but it is still pretty subtle. This one controls the clipping on the negative peaks of your signal.

Jumping down to the end of the article I went with example 9.

The pot here is a blend control going back and forth between a pair of hard clipping diodes and your raw guitar signal. The purpose of this is to provide some more subtlety that a simple on/off switch to select the diodes. The pot here would be the equivalent to using hot sauce: sometimes you want a lot and sometimes you only need just a little something. I kind of liked this one and may use it on a future project.

Working backwards I went to example 8

This pot is also a blend control between hard clipping diodes and a low pass filter (gets rid of the highs). Since I wanted to hear the full effect of the blend control I modded the Dist + circuit back to schematic stock values (only 2 capacitors and took me all of 30 seconds, if that). It's a very treble oriented circuit so this blend control seemed interesting to try. Lo an behold, it is!! Turning it fully ccw is the full clipping and very harsh sounding and as you dial it to the right you start taking off those nasty, ear piercing highs. Since it's a passive tone filter here there was a bit of volume drop.

Example 7

Like the previous example, this one blends clippers and now a high pass filter. To get the most out of this one I remodded the circuit (C2 and C4 to 100n). As you turn the knob to the right you start bringing out the highs in your tone to give it a bit of "sparkle" as said in the article and I agree wholeheartedly. This one is great to put into a DIY circuit IMO. Then again, Jack says this one would be great in a Dist + circuit, so go figure.

Example 3. Now we go into something called crossover distortion (sounds cool, right?)

The article suggests to use germaniums or schottkys to get the full effect, so I decided to use BAT41s. Honestly, I couldn't hear anything when going back and forth with the pot. I tried dialing back the gain a lot on the Dist + and couldn't hear anything. I guess I need to try this on a different circuit.

Example 4.

A crossover saturation control also attached to a LED (chose a red one). I tend to like the sound of red LEDs as clippers: less compression and more volume. However, I couldn't hear a difference in sound using the saturation knob. I'd like to think I did, but who knows?

Example 6

Blending hard clippers and crossover distortion. Despite the volume drop going toward the clipper side, I can honestly say I DO hear the crossover distortion when dimed to the right. It's very subtle, but it's there. To me it almost sounds like the tiniest amount of soft clipping, but not quite.

Example 5. A simpler variant of the above.

Altering the behavior of the same pair of clippers to act as either hard clippers or crossover distortion. It sounds very similar to the previous example and am relatively unimpressed. I'd rather use the hard clipper/full signal one instead.

My thoughts based on the above:

-I don't get crossover distortion. When I tried to hear it via youtube everyone just points to the oscilloscope showing its occurring and I hear very little change. Maybe because I'm just using my laptop speakers.

-General saturation controls and to add subtlety, nothing more. If you're a tone snob, and we all are to some degree since tone is subjective, you may want this.

-My best takeaway from this was the blend controls between the hard clippers and a RC filter of some kind, whether it be a high pass or low pass. These controls are also the most noticeable out of the 9 examples above. Sometimes you only need one tone knob to get a good sound and why not incorporate some clipping in there too.

 

[BuddytheReow]

Darlington/Sziklai Transistor pairs. Some good theory that opened up a world for me for circuit analysis.

I had a brain lightbulb go off recently. Actually it was last night when I was reading up on some circuit analyses and someone mentioned a "Darlington transistor pair" in a YouTube video so naturally I stumbled further down a rabbit hole. Once everything 'clicked' I realized how useful this can be and how common this is in many circuits.

(Small) Bear with me here...

A Darlington transistor pair consists of 2 transistors (either NPN or PNP) linked together that act as one whole transistor. The output of one transistor becomes the input of the other transistor. The schematics for either set are shown here


When linked as such, their common connections become one whole unit and the "new" collector/emitter is created.

The result? Increased current gain, and not just a simple 1+1=2. The product of the gains of each transistor becomes the total gain of the unit. If you're using 2n2222s with a gain of around 100, the gain of the darlington unit becomes 100 x 100 = 10,000 in theory.

There are a few disadvantages to using this. First, you have to have an input voltage large enough to make the circuit block work (voltage drop). Each transistor has its own voltage drop (~0.6v) so you'll need an input voltage of 0.6 x 2 = 1.2v. Not a big deal, but its there. The other disadvantage is that this circuit block becomes relatively unstable as the input current changes.

There is a solution to the above. It is call the Sziklai/Complementary Pair. Use a NPN/PNP combo. The schematic looks like this.

Why am I sharing this? Well, this is a circuit block used on many pedals out there and helped me "unlock" one of the schematic secrets out there.
A great example of this would be the PedalPCB Executive Fuzz, which is a Jordan Bosstone. I have highlighted the Sziklai pair in the schematic along with a mini-circuit analysis. I plan on writing up a breadboard tutorial soon for anyone who may be interested.

C1 and C4 are the input/output caps. Increase them to allow more bass to come through in this circuit.
R1 and R2 are the voltage divider to bias the complementary pair/unit.
R3 and C2 form a lot pass filter. If you remove C2 the sound gets thinner, but still decent.
C3 helps with oscillation. Best guess here considering the value and where it is located.
D1 and D2 are your hard clipping diodes.
The 2 pots are your pre-gain (think volume knob on your guitar) and output volume.

 

[bowanderror]

I've been stalking around Jack Orman's site http://www.muzique.com/ for a while and decided to go through his lab notebook. I chose his Saturation Control page to see how you can change the clipping depth of many circuits that use diode clipping. These are hard clipping circuits, not soft clipping. I would be curious to see how they could be done in, say, an opamp feedback loop but I don't think these ideas here can be transferred part for part. You would be adding resistance to the fb loop and would affect the gain. You can read his article here and all credit for this is to Mr Orman himself.

What's a simple circuit to try this out on? Why, the MXR Dist + of course! I chose to use the schematic taken from Beavis Audio's beavisboard project found here. If you're wondering how to whip this up on a breadboard it shows how to do that as well. Schematic is posted below. For purposes of this experiment I stopped building after C6. A volume pot is not necessary if I'm just experimenting. Plus, I tend to dime most of my dirt pedal volumes anyway. I also modded the circuit a bit too: change C2 to 100n and C4 to 100n. These 2 mods allow a LOT more bass to get through and gives your tone some balls!
View attachment 16308

Jack's article has 9 variations of the saturation control and I chose to experiment out of order than the article reads. I will label them 1 through 9 if anyone wants to follow along with my notebook/blog here. If there is a capacitor in the examples below right at the input I didn't breadboard them since I've already got an electrolytic already in there (C6). It's merely there as a coupling capacitor (I may write up something about capacitors soon).

First up is example 1. This is the basic saturation control.
View attachment 16309
I used 1n4148 diodes since they are the "standard" clipping diode IMO. When turned ccw there should be less resistance going to the diodes from the input signal and it should sound harsher per his article. When I tried this out it was VERY subtle turning the pot in either direction, but it is there. Even tweaking the gain pot of the Dist +didn't change the clipping sound that much. The sound is still very usable though. Oh, I should also mention if you've got the gain pot maxed out there will be clipping BEFORE the saturation control. This clipping happens in the opamp itself.

I then tried example 2.
View attachment 16310
Still using the 1n4148s, this is almost identical to the first example with the exception being that you're controlling only 1 of the diodes. I found this one to be a little less subtle that the first example, but it is still pretty subtle. This one controls the clipping on the negative peaks of your signal.

Jumping down to the end of the article I went with example 9.
View attachment 16312
The pot here is a blend control going back and forth between a pair of hard clipping diodes and your raw guitar signal. The purpose of this is to provide some more subtlety that a simple on/off switch to select the diodes. The pot here would be the equivalent to using hot sauce: sometimes you want a lot and sometimes you only need just a little something. I kind of liked this one and may use it on a future project.

Working backwards I went to example 8
View attachment 16313
This pot is also a blend control between hard clipping diodes and a low pass filter (gets rid of the highs). Since I wanted to hear the full effect of the blend control I modded the Dist + circuit back to schematic stock values (only 2 capacitors and took me all of 30 seconds, if that). It's a very treble oriented circuit so this blend control seemed interesting to try. Lo an behold, it is!! Turning it fully ccw is the full clipping and very harsh sounding and as you dial it to the right you start taking off those nasty, ear piercing highs. Since it's a passive tone filter here there was a bit of volume drop.

Example 7
View attachment 16314
Like the previous example, this one blends clippers and now a high pass filter. To get the most out of this one I remodded the circuit (C2 and C4 to 100n). As you turn the knob to the right you start bringing out the highs in your tone to give it a bit of "sparkle" as said in the article and I agree wholeheartedly. This one is great to put into a DIY circuit IMO. Then again, Jack says this one would be great in a Dist + circuit, so go figure.

Example 3. Now we go into something called crossover distortion (sounds cool, right?)
View attachment 16315
The article suggests to use germaniums or schottkys to get the full effect, so I decided to use BAT41s. Honestly, I couldn't hear anything when going back and forth with the pot. I tried dialing back the gain a lot on the Dist + and couldn't hear anything. I guess I need to try this on a different circuit.

Example 4.
View attachment 16316
A crossover saturation control also attached to a LED (chose a red one). I tend to like the sound of red LEDs as clippers: less compression and more volume. However, I couldn't hear a difference in sound using the saturation knob. I'd like to think I did, but who knows?

Example 6
View attachment 16317
Blending hard clippers and crossover distortion. Despite the volume drop going toward the clipper side, I can honestly say I DO hear the crossover distortion when dimed to the right. It's very subtle, but it's there. To me it almost sounds like the tiniest amount of soft clipping, but not quite.

Example 5. A simpler variant of the above.
View attachment 16319
Altering the behavior of the same pair of clippers to act as either hard clippers or crossover distortion. It sounds very similar to the previous example and am relatively unimpressed. I'd rather use the hard clipper/full signal one instead.

My thoughts based on the above:

-I don't get crossover distortion. When I tried to hear it via youtube everyone just points to the oscilloscope showing its occurring and I hear very little change. Maybe because I'm just using my laptop speakers.

-General saturation controls and to add subtlety, nothing more. If you're a tone snob, and we all are to some degree since tone is subjective, you may want this.

-My best takeaway from this was the blend controls between the hard clippers and a RC filter of some kind, whether it be a high pass or low pass. These controls are also the most noticeable out of the 9 examples above. Sometimes you only need one tone knob to get a good sound and why not incorporate some clipping in there too.

Nice writeup!

I've also played with some of these AMZ saturation controls, and also found them to be subtle with high Vf diodes (like the 1N4148), especially when fed by a single gain stage.

Because you're adding resistors to the mix, it takes a larger voltage signal to forward bias the diodes and audibly clip them. If you use lower Vf or softer knee diodes, the differences become much more audible. For low Vf & soft knee diodes, Ge diodes (or low gain Ge transistors with collector & base tied together) or diode connected MOSFETs work great. There is a great chart from Repair Cafe that compares the forward voltage & knee characteristic of over 30 diodes. Lots of interesting options:



You're also bound to run into opamp clipping with a single gain stage like the Dist+. I had much better luck with 2 cascaded gain stages, but a rail-to-rail opamp or running the circuit at higher voltage (12-18V) will also give you higher voltage gain before hitting the rails.

 

[bowanderror]

Welp, I think I found my limit. I thought my breadboard platform would provide nearly unlimited builds. While this is still true I forgot to figure in user error. My "protoboard" has 3 boards on it and I thought I could work on 3 projects simultaneously. Turns out after 2 things start getting really messy. Especially when I start crossing jumper wires for the various pots. It's always that 3rd build that starts giving me problems.

Not sure if I should post this here or at the Loafing Lounge thread.

Here are 2.5 projects before I called it quits: a MuffRat (schematic below and a nice med/high distortion), my L-PB&J Sandwich, and an attempt at Jack Orman's Son of Screamer. I gave up after the gain stage. Now comes the crappy part of taking it all down

View attachment 15865
View attachment 15866

I just found this thread and I'm really enjoying it. It's nice to see I'm not the only one who's had a few donnybrooks with a breadboard!

Originally, I also had 3 breadboards hooked together as an all-in-one protoboard, but it ended up being a pretty inefficient use of them, and I'd end up clumsily breaking jumpers off. My solution was to keep them separate and tape them on to clipboards as-needed. To keep the pot & switch jigs in place on the clipboard, I just use some blue tack on the solder side. It's non-conductive & fairly easy to remove when you're done.



The clipboards are easy to store, and the clip portion is helpful for holding things in place:



My recent epiphany was the use of 9mm PCB-mount pots in cut-down female headers. You have to bend the mounting pins to get a good angle for adjusting the pots, but they're easy to bend back into place if you want to solder them to a build later on. I also spent an hour cutting & stripping a TON of different-length jumper wires, which has reduced the amount of "spaghetti" in air over the breadboard. They also do a great job of holding breadboards together:

 

[BuddytheReow]

I just found this thread and I'm really enjoying it. It's nice to see I'm not the only one who's had a few donnybrooks with a breadboard!

Originally, I also had 3 breadboards hooked together as an all-in-one protoboard, but it ended up being a pretty inefficient use of them, and I'd end up clumsily breaking jumpers off. My solution was to keep them separate and tape them on to clipboards as-needed. To keep the pot & switch jigs in place on the clipboard, I just use some blue tack on the solder side. It's non-conductive & fairly easy to remove when you're done.

The clipboards are easy to store, and the clip portion is helpful for holding things in place:

My recent epiphany was the use of 9mm PCB-mount pots in cut-down female headers. You have to bend the mounting pins to get a good angle for adjusting the pots, but they're easy to bend back into place if you want to solder them to a build later on. I also spent an hour cutting & stripping a TON of different-length jumper wires, which has reduced the amount of "spaghetti" in air over the breadboard. They also do a great job of holding breadboards together:

I've also taken the time to make my own jumper wires out of my solid core 22awg. Not really worth posting here, but definitely worth the time and effort.

Great idea with the clipboard! I don't need to "clean up" my work area per se, but I just put it aside where the wife won't bother it. Things tend to work itself out.

 

[BuddytheReow]

I've been pretty busy over the past week or 2 with work and house projects. My last circuit tidbit was about Darlington Transistor pairs. I wanted to see this in action and whipped up a Bazz Fuss found via runoffgroove. It's an incredibly simple circuit composed of nothing more than a transistor, 2 capacitors, a resistor, and a diode. Here's the schematic for it.


Considering the component count this is a pretty decent sounding circuit. Lots of simple substitution mods for this.

What I decided to do with this is to A/B it with the stock circuit as one and the circuit with the Darlington pair in the other via a DPDT switch. Every other component was identical. I chose to use 47n caps for both the in and out just for kicks. Looking at my previous post, you can see that arranging the transistors in that configuration creates one MEGA transistor with gain levels in the 1000s.

My expectations for this were kinda high if I'm being honest. In the first minute or two of comparing the circuits they sounded EXACTLY the same to my ears. WTF? This should sound different with the MEGA transistor in there, right? Stay with me. After a few more minutes (In reality maybe 30 seconds) I realized that the difference sonically occurs when you hold a note or chord. The sustain on this lasts freaking forever! The stock sound dies out like a normal dirt pedal, but this one is ridiculous! With the amount of gain on tap here more signal gets pushed through the transistor and therefore the note decay lasts much longer.

Always nice to see an application of what you might read in a textbook. Btw here's my breadboard with both circuits. I used 2n5088s.

 

[BuddytheReow]

Hey All,

About a month or two ago I pulled the trigger on a Muffin Fuzz board and it's been sitting on my workbench since. Once I finally got my protoboard up and running (big thanks to @fig ) I decided to start going through all the different variants via PedalPCB's Muffin Fuzz. There are 9 variations out there and there are 2 that I may not do simply due to either not having the correct components on hand (Bigger Muff) or the schematic doesn't mention a few components (Double G Overdrive).

First up is the Martian version. In a separate thread I had a theory question why the input stage had only unity gain on my board. Turns out I had the bjt flipped around. Another point for user error . Anyways, this version definitely has an octave up sound to it and reminds me of the hyped fuzz board I built a year ago or the ionizer. You can definitely get some Electric Wizard type sounds out of this one! I really like it with a downtuned guitar on it. Will this one be the winner for my board? Honestly, probably not since I have others that sound similar to this one.

Since I have the layout figured out from schematic to breadboard the other versions will come together much quicker.

 

[fig]

I have some catching up to do here! I just read through your darlington pairs write-up and re-post, a fantastic read for someone wanting to better understand a LOT of popular circuits. Your illustration should light up more than a few lightbulbs! (it lit my fire) Thanks

 

[Chuck D. Bones]

Very clean layout!

 

[Chuck D. Bones]

At first glance, I thought this said "TWAT."

 

[BuddytheReow]

Very clean layout!

Thanks. Making my own jumpers makes the picture look better. That and I really don’t like using the prepackaged ones unless I have to. They tend to be either way too long or short

 

[Chuck D. Bones]

I make my own jumpers too. but I'm not quite A/R enough to make them exactly the right length or run them along the grid lines. And that explains why I have parts and jumpers in the wrong place sometimes.

 

[bowanderror]

At first glance, I thought this said "TWAT."

View attachment 19128

Sometimes my internal monologue gets externalized.

 

[BuddytheReow]

Been a while since I posted here, but I have some flexibility this week in between holidays to work on some breadboarding. Last week Dirtboxlayouts posted a handful of Devi Ever circuits. Devi's circuits are relatively simple for the desired effect. This is an overdrive circuit called Devi Ever Electric Brown. https://dirtboxlayouts.blogspot.com/2021/12/devi-ever-electric-brown.html

A skill that I wanted to work on was to convert a layout (stripboard, p2p, pcb, etc.) to a schematic and then breadboard it. It didn't take too long to figure out, but what stumped me for a while was the purpose of the second transistor. I'm not cheating here, but below is the schematic I found that matches what I did (my handwriting ain't the best). See the top schematic. I think it's purpose is to act as a diode since the emitter is not used at all. Can anyone chime in with their analysis/purpose of the second MPSA18? I added a switch to compare the sound at one transistor vs both and it's subtle, but it's there. Pardon the messy layout since I'm usually pretty anal about that stuff, but I said screw it this time.

Anyway, this is an ok transistor based overdrive. You need to dial in the pre-gain pot to remove some of the gating. If you've got the parts laying around this is definitely one to try.

 

[Chuck D. Bones]

To say that Devi Ever's circuits are unconventional is a gross understatement. Makes it very difficult to sanity-check the traces and Vero layouts. How did you switch the 2nd transistor in/out? A series switch that creates an open circuit or a parallel switch that shorts B to C? I think a regular Silicon diode would work in place of Q2. Whatever that 2nd transistor does, it must only do it during the note attack. That 100nF cap blocks DC and the transistors C-B junction only lets current flow one way. OK, there's a tiny reverse leakage current. The C-B diode might turn on briefly
during the attack of a note or chord. IDK.

 

[BuddytheReow]

To say that Devi Ever's circuits are unconventional is a gross understatement. Makes it very difficult to sanity-check the traces and Vero layouts. How did you switch the 2nd transistor in/out? A series switch that creates an open circuit or a parallel switch that shorts B to C? I think a regular Silicon diode would work in place of Q2. Whatever that 2nd transistor does, it must only do it during the note attack. That 100nF cap blocks DC and the transistors C-B junction only lets current flow one way. OK, there's a tiny reverse leakage current. The C-B diode might turn on briefly
during the attack of a note or chord. IDK.

The switch is where the volume pot should be. The bottom cap I put right after the collector of q1 (one end of the switch is here) and I also added a jumper wire from that to where the volume pot would be. Both caps meet there and that’s my other switch point. The middle lug of the switch is output.