Blog Posts

The New Wave CV Generator released

9/26/2017

Here's a new DIY project that is a bit unusual. The "New Wave" is a Control Voltage Generator - two LFO's (Low Frequency Oscillators) in one box that you can use together with other pedals or synthesizers (with CV inputs) to modulate the sound of those devices (it doesn't do any sounds on its own).

Features:

Four different output modes:
1. Square wave
2. Triangle wave (or saw/ramp)
3. Sample & Hold
4. Sequencer (3 or 4 steps)
Slide - Smooth out the waveshapes (a.k.a. "portamento")
Switchable 5v or 9v operation and maximum output (Vpp)

It can be used with other Parasit Studio pedals such as the Into the Unknown, U-235 Suboctave Generator, Raygun Youth Fuzz, and many upcoming projects. Some old projects will also be updated with CV inputs.

The idea behind this project was inspired by modular synth design (let's bring some modular thinking to the pedal world!) and the name New Wave is inspired by the New Wave of punk and the New Wave of British Heavy Metal in the 80's.

The PCB is avaliable now in the shop

I have not made a proper demo yet, but here are a couple of examples.

The first prototype didn't have the slide and depth controls

The CV Generator is used from about 2 minutes in

I hope you like it! :)

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The U-235 released!

9/11/2017

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Here's a new DIY project that I have been working on for a while -
the U-235 Suboctave Generator.

In short, it's an analog monophonic octave down pedal.

I wanted to do something a bit different, so this pedal uses a CD4046 PLL to do the freqeuency dividing, insted of a D-flip flop that are typically used in analog octave down pedals. This allowed me to add a couple of fun features like the Detuned Mode and the CV input.

Here's a short demo (the fun part starts at about 2 minutes in...)

It will work best for guitar since the tracking gets alittle bit slower at the lower notes, but you can clean up the tracking by using the neck pickup. I also have found that it helps alot to palm-mute the strings alittle bit when playing the lowest notes.

I will not share the schematic for the U-235, so please don't ask for it. But when I have time I will try to write another part for the CMOS Workshop series that will explain how to set up the 4046 as a frequency divider so that you can breadboard it yourself and play around with it.

I hope you like it. :)

PCB avaliable now in the shop
Assembled pedals coming soon

U-235 Suboctave Generator PCB

In the last half of the demo I'm using the "New Wave CV Generator" (more info on that project coming soon) as a Control Voltage source, but you can hook up any LFO, from a synthesizer or another pedal.

..or why not build your own simple square wave LFO on a piece of veroboard and put it in the same enclosure? :)

Building tip: Make the input and output wires as short as possible. There's alot of high amplitude square waves going on inside the circuit and it can easily bleed into the clean signalpath, making it sound less clean than it's supposed to be. Never run the wires under/over the board. Just a small thing to keep in mind.

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New versions released, upcoming projects and more!

6/27/2017

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I'm happy to announce two new projects coming soon, summer sale and more!

It's been a long time since I posted anything. I've been very busy lately, working, touring and doing other projects. It's been hard just to keep up with the emails i'm getting every day, let alone work on new stuff. But in the last couple of week I've finally had some spare time, and I've managed to complete a couple of projects that has been brewing for a long time. I hope you find these interesting. :)

Coming soon!

1. U-235 Suboctave Generator

The U-235 is a "clean" octave down based on the CD4046 PLL chip.
It tracks very well both with guitar and bass.

It has three modes:
1. One octave down
2. Detuned (in between one and two octaves down)
3. Two octaves down

Here's a quick phone demo using the bridge pickup on my SG.

Prototype build.

I built the prototype on vero. I will share the layout once the PCB's are ready aswell.

2. The New Wave CV Generator

The New Wave is basically a stand-alone LFO board that can be used with synths or other effects to modulate the sound with various waveforms. It doesn't make any sounds on it's own.

It has one CV output that can be toggled between 4 modes:
1. LFO 1 - square
2. LFO 2 - saw/sine/ramp
3. Sample and hold
4. Sequencer (3 or 4 steps)

First prototype build. The final version will look a bit different.

In the demo i'm using it with the Into the Unknown guitar synth which already has a pad on the PCB for a CV input, but several parasit studio projects will be updated with optional Control Voltage inputs, such as the 0415 Guitar Synth, Sentient Machine, Green Currant and more.

The CV range is switchable between 0-5v or 0-9v.

More into coming soon on the new projects!
I expect about 5-8 weeks until release.

New PCB versions released!

1. Xor'cist 2.0

Here is a much improved version of the Xor'cist, with the fat trimmed. It's now a much simpler and straight forward build. It has a redesigned input stage, so issues with ringing notes and oscillation should now be a thing of the past. :)

2. Sonic Reducer 2.0

The Sonic Reducer has also gone through a complete overhaul. It's also easier to build, and has no longer any need for a JFET. :)

3. Green Currant Tremolo 1.5

This PCB has gotten a facelift, and is now green to fit the name. Circuit-wise it's the same.

4. The Sidescroller 1.5

The PCB has also gotten a facelift.

Four new versions of old projects are released and now avaliable in the webshop.

I also have new 3PDT-boards with LED + CLR in stock.

SUMMER SALE!

To celebrate these news I now offer a 10% discount in the webshop.
Just enter the code "summersale" at the checkout. Valid until 5/7.

That wraps up this long overdue post. I hope everyone out there is having a great summer.
Cheers // Fredrik

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New PCB updates released: Into the Unknown 2.0 and more!

1/12/2017

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3 PCB projects has been updated and are now avaliable in the webshop. :)

1. Into the Unknown 2.0

The Into the Unknown has been updated to solve the ticking issue that some people were having.

The LFO now completely shuts off in the middle switch position, to avoid ticking when not using the LFO.
A LFO gate is also added (similar to the Arcadiator) which shuts off the LFO when not playing. This gate can be switched on/off with board mounted DIP switches.
The filter and the gate pot are now reversed to easier reset the pedal by turning all pots counter-clockwise.

3. Subspace Transmission 1.5

The first Subspace Transmission PCB suffered for below unity output volume. This has now been fixed with the new PCB.

2. The Corruptor 2.0

The Corruptor has been updated significantly to be more than just a ring modulator. It's now also a octave fuzz!

Improved overall circuit and layout
Extra gainstage added for better sustain
Blend control added to let you blend between ringmod sounds and square wave fuzz
Octave up switch added for the fuzz side
Modboard connections added for possible ringmod carrier frequency modulation

Demo of the old Corruptor. A new demo for the updated version is coming soon.

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CMOS Workshop Part 4: octave up

1/3/2017

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It's time for another part of the CMOS Workshop series. :)
This part will be about octave up circuits (aka frequency doublers).

The easiest way to produce a digital octave up is by using a Pulse Generator circuit, also called a Edge Detector. It generates a pulse at every high-to-low and every low-to-high logic transition, thus doubling the frequency.

It's a simple circuit and what used for the Arcadiator. There are several ways to do this. Let's have a look at a few examples and start with the easiest way that require the least amount of components.

You can click on the images for a larger view.

The top row shows the square wave and the bottom row shows the pulses generated with the edge detector circuit

1. XOR gate (CD4070)

The CD4070 is ideal for this purpose and require very little extra components.

XOR pulse generator schematic

XOR logic: For the output to go high, both inputs needs to be at a different state

By connecting our square wave to both inputs and delaying one of the inputs slightly, there will be a brief moment when the inputs are in different states. At this moment the output will go high, thus creating a short pulse wave at the output every time the input goes high or low.

The delay is made out of a simple RC filter. It will round out the square wave, so that it takes alittle longer for each transition to cross the switching threshold of the logic gate.

Lets try this circuit on the breadboard. Remember to always disable all the unused inputs.

XOR pinout and truth table

Here we can play around with different values for the RC filter. It will change the width of the pulses and the character of the sound. For C5 (C1 on the schematic) try a 4.7nF - 47nF value. For R5 (R1 on the schematic) try 10K-500K. In the 1B example I've replaced R5 with a trimmer and for convenience I chose another gate. The top greyed out part is the gainstage and schmitt trigger front end from the CMOS Workshop part 2 so you will have to check the other component values there.

Notice that the pulse width can get too narrow or wide for the octave up effect to work. As a rule of thumb you don't want the pulses to be too narrow because it will sound bad, and you don't want the pulses too wide because then it won't track properly on the entire fretboard.

If you don't have any CD4070 chip at hand you can use a CD4011 chip to homecook one XOR gate our of four NAND gates.

But what if you don't have that either?

Surely you must have at least one CD40106 or a CD4093 chip laying around. We can use "Mickey Mouse Logic" that I have mentioned before to make four NAND gates out of four schmitt trigger gates by using diodes and resistors, then connect them together to form a XOR gate.

It's possible but silly. The amount of components required is rediculous.
There are other much easier ways if you want to use a schmitt trigger chip... :)

NAND gates connected together for XOR logic

"Mickey Mouse logic" using schmitt triggers

2. Schmitt Trigger (CD40106 or CD4093)

With a schmitt trigger gate we can make a simple edge detector shown to the right. However, it's only producing a pulse each time the input goes high (or only the opposite), so it's not really what we want for an octave up effect. It basically just changes the pulse width (this is how Tim Escobedo's "PWM" works).

So how can we turn this little circuit into a frequency doubler? Simple, we just need two of these and one inverter. One edge detector for the negative edge, and one for the positive edge. Then we simply invert one of the pulse outputs and sum them together and we have a frequency doubler. :)

Schmitt Trigger Octave Up A

Schmitt Trigger Octave Up B

This circuit produces a negative going pulse at each transition from low to high at the input

If we connect the resistor to V+ insted of ground, the circuit will work the opposite

The pulse outputs of the two edge detectors

The B schematic is just another way of doing the same thing. I just moved the inverter to the input insted.

Lets put it up on the breadboard!
C1/C2 = 10nF, R1/R2 = 47K, R3/R4 = 10K

Here you can play around with the R1/R2 resistor values for different pulse widths. This way of making a frequency doubler also has a couple of benefits over the XOR version. You can connect a LFO directly to R1 (or R2, or both) to modulate the pulse width. You can also switch in/out the second edge detector to toggle between octave up or a pwm sound, just like the Arcadiator.

Schmitt Trigger octave up with possible mods

Schmitt Trigger Octave Up A

In the last schematic I added an offset trimmer to the LFO input, which would probably be needed along with some attunement of the LFO voltage. Experiment! :)

3. Octave up using rectifiers

This is not really CMOS related, but I thought I'd just give a quick and crude explanation of how an octave up circuit works using rectifiers. It's probably the most common way of making an octave up circuit for guitar effects.

Simply put, the signal gets split into two signal paths (one is being inverted), then two rectifiers (one per sinal-path) cuts off half the waveform and then both rectified signals gets summed together (so in a small way it resembles the schmitt trigger method).

I won't go into any more detail about this method. There's plenty to find out if you google about half wave and full wave rectifiers. A rectifier octave up circuit is what I'm using in both the Eagle Claw and Sidescroller Fuzz.

This shows a very simplified waveform to give you an idea of what is happening. Sorry about my crappy handwriting :P

Just as the schmitt trigger schematics showed, the inverter can be placed after one of the recitifiers insted if one of the rectifiers is cutting off the opposide side of the waveform.

The rectifier method generates alot of distortion as it's clipping the signal. There's no easy way to do clean octave up in the analog domain.

4. NOT gate (CD4069)

There's one last version I would like to include in the article, similar to the schmitt trigger one, except that it uses regular inverters.

Octave up using five inverters / one CD4069

This version will only work with a prettly low value pulldown resistors since a regular inverter gate has no built in hysteresis to take advantage of. Use 4.7k resistors for R1/R2. To set the pulse width, play around with the cap values insted. When I breadboaded this I got good results using 150nF for C1/C2. The two extra inverters are there to clean up the pulses which looks kinda crude at the output of the first inverter, but it will work ok without them.

And last but not least, here's a video that shows the waveforms on a scope. The yellow line is our original square wave and the blue line is the pulse ouput from the edge detector circuit. I'm playing around with the pulse width, and as you can hear, it changes the sound from full to thinner and more nasaly sounding.

That's all I had for this part.
I've given some examples of how to make frequency doublers with edge detector circuits using at least 5 different CMOS chips (if you count the schmitt trigger variations). Which one you choose will probably depend on the rest of the circuit you are making. Maybe you already need a schmitt trigger chip in your circuit to do other functions, then example nr 2 is better because you will still have 3 gates left over (if using a CD40106) insted of adding an xor chip to only do one thing. Personally I prefer to keep the chip count as low as possible even if it adds more components. It usually takes less time to solder a few extra resistors and caps then having to solder another 14 or 16 pin chip (which also takes more space on the PCB). It's all about convenience.

As I've shown, there's usually several ways to do the same thing when working with CMOS. Remember that we're dealing with 1's and 0's, so no matter which chip/method you use it will basically sound the same (if the pulse width is equal). Same goes for the octave down methods in the previous part. However, there is a clearly sounding difference between edge trigger or rectifier doublers, or PLL VCO frequency doublers (as used in the Into the Unknown guitar synth) which I will cover in a later part.

But next part will be about oscillators and LFO's.
We will breadboard some fun stuff, as I've promised :)

UPDATED 2023-10-31: Some minor spelling corrections.

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Arcadiator 2.5 released!

12/20/2016

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Update 2016-12-20: Updated the info for the 2.5 version

Here's a minor update for the Arcadiator.

Changelog:

Optimized circuit
Improved schmitt trigger
Fixed clean blend mod

Read more about the mods in the build document.

The Modboard
Also released is this small LFO trianglewave daughterboard.

It can be connected together with the Arcadiator to modulate the pulse width for even more C64'ish sounds...
Many Parasit Studio boards will have Modboard connections in future revisions that will allow for new crazy sounds.

The modboard can be used to modulate just about any pot in any circuit that is set up as a variable resistor. You just have to experiment with the type of vactrol (or LED+LDR) to find the one to best suit your purpose.

PCB's avaliable now in the shop

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RIP Wookie and Ray

7/25/2016

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Wookie 2010-2016
Alittle over a month ago I lost my pet, my best friend and companion that I've had for the last 6 years. Her name was Wookie, a wonderful and very special dog.

She could do a ton of tricks (some that she came up with herself). She loved to take long walks, jump up on things, swim, play and training (agility). he was very social and loved to just hang out, even when I was recording bands. She would often fell asleep at the feet of singers while recording (even screaming vocals). She always knew when we were planning stuff. Even when we talked quietly she could pick out words out of long sentences and get totally psyched for something to happen. She was very intense (alittle bit of a nutcase in a good way) with all her emotions on the outside. Easily stressed and fragile but very fun, warm and loving. Wookie my sweet darling, I love you and I miss you.

Because of her passing I kinda lost my inspiration for pedal building and breadboarding new things, so that's why there's been very few blog updates lately and I apologize if I have been slow to reply when people are asking for help. I hope that some inspiration will return to me eventually because I have alot of ideas that I have not explored yet.

Ray Wilson 1955 - 2016
I would also like to dedicate this post to Ray Wilson - A true DIY legend within the synth DIY community and the creator of Music from other space. He recently passed away, and it saddens me alot. He was a big inspiration to me and his book Make: Analog Synthesizers got me interested in making pedals with cmos. It has a very brief but good chapter about cmos uses that led me to buy the CMOS Cookbook and without it I would not have come up with ideas for many of my pedals. I also was in contact with Ray a few times and he always wrote excellent replies (I still have a Subcommander Guitar Synth PCB waiting to be finished). Thank you Ray for your great contribution to the DIY community and for being a true inspiration. Rest in Peace.

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The Xor'cist released!

4/19/2016

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edit 2016-04-26: Limited edition fully assembled pedals now avaliable!

Here's a new DIY project - the Xor'cist stutter fuzz and ringmod. It's now avaliable as a PCB and as a fully assembled pedal.

I have been wanting to do a CMOS based squarewave stutter fuzz (a choppy on/off type tremolo) for quite a while. I have also been thinking about doing an extended version of the Corruptor ringmod (without the over-the-top sequencer of the King Corruptor) so I decided to combine both these ideas into one circuit and this is the result. :)

It can do fuzz, ring modulation or a blend of both. With the stutter engaged it will do stuttering fuzz, stuttering ringmod or alternating between fuzz and ringmod (depending on the mix knob setting). The momentary stutter footswitch can be disengaged and the LFO can be off/on/gated.

The Xor'cist uses a CD4070 XOR chip (hence the name) to achieve both the ringmod and the stuttering effect. It's basically the bastard big brother of the Corruptor.

PCB and complete pedal avaliable in the webshop

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Subspace Transmission Fuzz released!

3/18/2016

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Here's a new DIY project called the "Subspace Transmission Fuzz"

This is a fuzz with a recording and playback feature based on the ISD1820 voice recording chip. It can record up to 20 seconds and the playback can be repeated and pitched up or down. It's perfect for playing along to your riffs and coming up with new ideas, or why not make a short repeating loop and pitch it down for some sick drone sounds!

Please note that it can't be used to do overdubs because of the limitations of the chip and the repeat is not fluid, but it's still pretty awesome what a 14 pin dip chip can do. :)

I hope you like it!
/ Fredrik

PCB avaliable now in the shop

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The Sentient Machine

3/8/2016

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Update 2016-03-16: I added a vero layout

It has been a slow start to 2016, but a few new projects are finally coming together. Here's a new DIY project - The Sentient Machine.

It's a resonant lowpass filter modulated with an LFO. It has a couple of different voice settings, a standard wah sound and a special vowel sound. At slow speeds it makes a cool spacey sweeping sound reminiscent of a phaser, and at minimum depth and medium speed it almost sounds like a tremolo.

This circuit is pretty advanced, but it's a straight forward build. The PCB is made to fit inside a 125B enclosure.

The madman Savvas (@tagboardeffects) submitted a vero layout. Thanks! Please note that it's not yet verified.

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