22/7 4069

RunOffGroove 22/7 4069

First build of 2022! This is a 4069 version of RunOffGroove’s 22/7. The original uses the 4049 hex inverter. This the same circuit using the 4069. Both chips contain 6 inverters but the they differ in format and layout. The 4049 is a 16 pin DIP and the 4069 is a 14 pin DIP. One is a drop in replacement for the other.

While it’s possible to make an adapter I decided to make a a new PCB based on the 4049 board I had already made since the board will be more reliable and make a better build than using an adapter. Now days it’s cheap and easy to have boards manufactured. The cost is around $20 for 10 boards is money well spent if you consider the time invested make boards from scratch. I had these boards made at PCBWay.com. They service is pretty cheap and easy to use.

Build your own 22/7

You can order these boards and build your own! Order from the shared service at PCBWay here. Then follow the 22/7 Build Guide.

Does the 4049 sound different from the 4069? Not that I can tell. But discerning ears might detect a subtle difference. I’d like to hear your opinions. The best thing about this project is that it this is a a great sounding circuit and it gives me a place to use this bag of 4069 chips!

Tim Escobedo’s PWM


Tim Escobedo was this wildly creative force in the early DIY Stomp Box community. His circuit snippets page was had a lot of really great ideas. One of the ideas there was the PWM, which stands for pulse Width Modulation.

This circuit converts your input signal into a square wave and varies the amount of on and off time or duty cycle of the wave.

I had these boards manufactured through PCBWay.com. The quality is great. Ignore the bad silkscreen that was my fault. The cost was $5 USD for 10 boards which is very reasonable.

I designed this board to fit a 1590B enclosure in landscape. The cutout is for the power jack. I thought it would work well… After getting the boards I realized I would have trouble getting 500k 9mm pots that mount at 90 degrees. I going to have rethink this project. I also botched up the silkscreen. This is going to need a second try.

UBE Screamer 4069

UBE Screamer 4069

This is a version of the UBE Screamer using the 4069 in place of the 4049. Essentially these chips are the same. They both contain 6 inverters. The 4049 is a 16 pin DIP while the 4069 is a 14 pin DIP. Electrically the should the same but the pin arrangement is different.

The original circuit from RunOffGroove.com is a very interest evolution of the Ibanez Tube Screamer TS-808. RunOffGroove has an article describing how to make an adapter that adapts a 4069 to a 4049.

I decided to just make another PCB since I had already created a PCB for the original 4049 circuit. The adapter would work but ordering some PCBs from PCBWay.com costs about $25 for 10 boards which worth the time spent hacking a solution. And, the boards are well made and reliable!

22/7 4069

22/7 4069 PCB

Here is a version of RunOffGrooves 22/7 using the 4069. The original circuit uses the 4049 Hex inverter. The 4049 is a 16 pin dip with 6 inverters. Here is the 4049UBE data sheet.

You can see it has 16 pins with 6 inverters. There is a power Vdd pin 1 and ground Vss pin 8. And two unconnected pins 13, and 16.

The 4069 is essentially the same chip. Here is the 4069 data sheet. Here is a picture of the chip:

The 4069 is a 14 pin chip with 6 inverters. Pin 14 is power and pin 7 is ground. There are no unused pins.

The two chips should be the same and interchangeable. Of course we of discerning audio tastes can sometimes hear subtle differences in devices. So of course we have to build both and see what they sound like!

RunOffGroove.com has notes on building an adaptor. You can check out the instructions here.

I had the PCB designed for the 4049 already and PCB manufacture these days is pretty inexpensive. I updated my 4049 design and had some boards made. It cost about $25 for 10 boards. I figure that’s worth the couple hours time it might have taken to make the boards myself, and I get high quality boards! Manufactured boards have two sides, are pre tinned, and have tighter tolerances which allow you to get more in a smaller space. I used PCBWay.com low cost prototyping service to create these.

UBE Screamer v2

UBE Screamer 2 PCB

I made an update to the RunOffGroove UBE Screamer from a suggestion in their notes. This version adds a mix control the blends some of the original signal with the distorted signal.

The original uses Rx to set a fixed mix amount. The notes suggest a value of 100K to 470K for this resistor with a 100K for lower output pickups like single coils and 220K to 470K for hotter pickups like humbuckers. There is a suggestion in the notes to make this a trimmer. With this board I made this an outboard control.

These boards were done through PCBWay.com. The quality is great. It was abut $25 for 11 boards so the price is pretty reasonable.

I built his up and after testing I realized I needed another resistor in the mixing section. I should have seen that earlier, oops. This wasn’t hard to fix by cutting the leg off the blend pot and inserting a 100k resistor in its place. This idea will take a another revision to get it working as it should.

I left R13 out. This is needed mixer is not working when the Blend pot is at a low resistance. I clipped a leg off the blend pot and replaced it with a 100k resistor as a patch. Then updated the schematic.

1981 Inventions DRV clone.

Here’s a PedalPCB Informant. This is mostly the Rat circuit with a few changes. The biggest change is the addition of a charge pump. The charge pump provides a +9 and -9 volts power for the circuit to run off. Effectively this doubles the voltage.

I have some reservations about the power supply. The clipping section clips at a fixed point. After the clipping diodes the charge pump doesn’t make any difference. With only a 9 volt power supply the circuit would running off +4.5 and -4.5 volts and there would be plenty of headroom going into the clipping section. The clipping section uses silicon diodes which will clip the signal at 0.7 volts. Which means the signal can’t really get past +0.7 volts and -0.7 volts. After the clipping section the output buffer is unity gain so nothing is added there.

The circuit does have a buffered bypass. The PedalPCB Informant offers an option to make this true bypass. The original DRV is buffered. I went with a buffered option. Here the charge pump can offer something since the buffered output can use the entire +9/-9 volt swing.

I built this is from a PedalPCB Informant PCB. The board is a great quality and set up for an easy build with all of the pots and LED mounted to the board. I would be happier to put this in a 1590B enclosure but the board is a little too large. On the other hand using a 125B allows for all of the jacks at the top.

The cost of this project was about $25. Which is pretty reasonable and took only a couple hours. The parts are all easy to get. Nothing special or hard to source. You can get everything for this at Tayda Electronics including the charge pump.

I milled the enclosure, filled the engraving with some paint and sanded the enclosure after. there is a small hex bolt between the knobs at the top. I drilled there for an LED but realized I had some of those stomp switches with the LED ring later and decided to use one of those. I used the hex bolt to fill the hole.

UBE Screamer 1.1.1 build

Built and tested the new version of the UBE Screamer PCB. Everything is working! Sounds great. This is a good alternative to the standard TS-808 and other overdrives if you’re looking for something a little different. Does great low gain sounds.

I built this in a 1590B enclosure from Tayda. I got most of the parts from Tayda as well. They still the 4049UBE Hex inverter. The cost was about $20. The build is easy. With all of the pots and LED mounted to the board the assembly simple. I used the same layout used over at PedalPCB.com for the PCBs. Power connections are at the top and all off board wiring is at the bottom.

You can build this project for yourself. Follow the build guide here. Or buy one already built from my Reverb Shop!

Wata’s Electro Sound Big Muff

I heard this new song by Boris and it got me interested in the band again. This is apparently an add for a new EarthQuaker Devices pedal. If you haven’t heard Boris you should take a listen. They are on BancCamp here.

Reading an interview with the guitar player Wata. It mentions the Hizumitas, her new signature pedal from Earth Quaker Devices, being “A painstaking recreation of the Japanese alt-rock icon’s beloved Elk BM Sustainar.” I had to look this up.

Turns out the Big Muff Page has me covered with some background history and a schematic! Looks like this version of the Big Muff is most the standard circuit. The one biggish exception is that it uses PNP rather than NPN transistors.

Here is what the Big muff Page has to say about the ELK Big Muff Sustainar:

ELK BIG MUFF SUSTAINAR / SUPER FUZZ SUSTAINAR  – Among the many Japanese Big Muff clones, one of the first on the market was the Super Fuzz Sustainar, a nearly exact clone of a 1972 era Big Muff made by the Hoshino Gakki company (early units possibly made by Miyuki Ind. Co.) sometime around 1973. It was housed in an identical enclosure to the V1 Big Muff with very similar graphics. These were sold throughout the 1970s, and not long after its introduction, Gakki shamelessly changed the name from Super Fuzz to Big Muff. The pedals marked Electro Sound are the earliest, and those marked Elk Incorporated or Elk/Gakki are the later made production. 

The circuit is identical to a PNP triangle circuit from 1972, almost identical to the PNP circuit shown above. The only change made was the high pass cap in the tone section at C9. Typically .004µF, it was changed to 330pF in the Sustainar. This had the effect of retaining treble when the tone pot was turned to the bass side, making the bass range more useful. When fully in the bass position the overall volume level is significantly higher than other tone settings as well.

The transistors used were NEC A733. I looked these up. They seem pretty standard but lower gain. The data sheet I read shows typical HFE of 90 to 200. Looking online I found 10 for $8.65. That’s $0.87 a piece for some meh transistors. Looking in my parts bin I found a bag with some PNP types in similar gain range.

Speaking of Big Muffs with low gain transistors, I think these sound really good. My favorite Big Muff is a clone of the Way Huge Swollen Pickle Jumbo Fuzz. It uses a transistor array that has four low gain 2N3904 transistors in one device. These transistors are in the same range Hfe range ~200.

Using the PNP types would mean the circuit would have a positive ground. With the consequence of using a daisy chained power supply being all of the noise from your other pedals would be going through audio of this pedal. It would be possible to use a charge pump to generate a negative voltage from a positive supply but this seemed more work than it was worth.

Looking through my parts I found some NPN transistors that measured about 200 to 285. Which seemed in the ballpark. I decided to use these. I can use a standard power supply, and no battery.

Now I need a PCB. This would be a good test for my MiG Buff board. This board is printed with the part numbers uses by all of the schematics on the Big muff Page! I had a board and some transistors it was time to get started!

Order some boards, find a schematic on the Big Muff Page, and follow the instructions here to build your favorite version of the Muff.


Built the board on one my BMP PCBs. I had a run of these made at PCBWay.com. You can order this PCB from their shared service here.

I soldered up the boards and used what I had on hand. It was great not having to order parts. The transistors were 2N2222A types in these little metal cans. They look super old school.

Next I found a Black glossy powder coated 1590B enclosure. I setup the mill and milled the box. I spent a little time in Sketch setting up the art.

I fit the PCB, pots, and LED into the box and soldered it all up.

Then I wired it up and tested!

How does it sound? Sounds like a Big Muff! It also has some secret sauce that gives it it’s own unique flavor of the Big Muff sound. The tone Stack is has a different feel. Part of this is because the pedal uses Audio taper pots. The change in C9 also is noticeable. When you get the dial around to the bass side. The lower gain transistors provides that singing sustain and a bit of note bloom, especially when you play with a light touch.


Next to nothing. I was able to build this with parts that were laying around and left over from other builds.

Yet another Big muff

Does the world need another? I wanted to do a Big Muff using those 9mm pots. These seem like they might be a good build option. I also wanted to setup this PCB to use the same part numbers that appear on all of the schematics not the Big Muff Page. This way it would be possible to easily build any version from the many schematics there!

22/7 PCB Order

I just got these PCBs in the mail from https://www.pcbway.comPCBWay.com. I’m impressed with the quality. This is an update of my my 22/7 PCB. I made a couple small improvements.

The 22/7 is a CMOS based Big Muff. A very cool and innovative circuit by RunOffGroove.com. Did I mention they just turned 20 years! If you like the Big Muff but would like something a little different try this.