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Messages - paulsoulsby

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Fault report / Re: Very loud mains hum from audio out
« on: January 14, 2018, 12:53:51 AM »
Hmm hope it isn't the soldering on that socket.  I'll probably have to ship it back to me to fix it if it is, as soldering that joint isn't an easy job.

Couple of things to try before getting to that point:
1)  Pull the cable off of the header.
2)  Scratch a screwdriver on the header pins to make sure there's a good metallic contact and there isn't any dirt or gunk on them.
3)  If you have a small flathead screwdriver, push it into the little long thin gaps on the white header socket. This releases the metal clips so the white plastic part of the socket comes off.  Look at the 2 pins, are they bent flat? If yes, try and reshape it so it looks like this: 
4)  Then reassemble and reattach cable.
Another option could be for me to post another blue cable to you. It's fairly easy to replace, you just need pliers to remove the 1/4" jack.

Don't worry if any of this is too much effort or goes wrong, email me and I'll arrange a return. Just trying to avoid you having to be parted from the synth!

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: January 12, 2018, 12:10:03 AM »
You can download all the libraries:
and .ino:

or just use Easy Uploader and the .hex file.  It'll def work with any Arduino Uno. I assume you've installed the Arduino IDE which has the Uno drivers.
Click "show console" and copy and paste the error and I'll tell you the issue.

Atmegatron Librarian / Re: Atmegatron librarian CPU usage
« on: January 10, 2018, 11:18:56 PM »
Hi.  I've just done some tests.  I'm afraid I don't have any machines left on Win7, they're all on Win10, but I'd imagine the problems would be reproducible on both OSs.
I did a fresh install of the 64-bit installer on website.  The machine didn't have any Java or Netbeans (the IDE it was written in) installed.

I did notice that the installer behaved very oddly. It sat there for a good couple of minutes doing nothing, but eventually it did install successfully.

I then launched Librarian and it behaved completely normally. The Task Manager was showing 30-40% for Librarian, but no other apps were doing anything!  I thought a fairer test would be to play a Youtube vid in the background and see how it coped.  Screenshot attached. 

The performance of the app isn't great, but Java is famed for being processor intensive.  I don't think there's actually anything wrong with the app.  It's not bad enough for my laptop to heat up or anything!

Could you try completely removing Librarian and all Java run time installs.  Then download and install Librarian again.  It has the Java environment inbuilt to the installer, so no need to install Java manually.

Let me know if it starts behaving then!

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: January 10, 2018, 11:01:44 PM »
Looking really good! The mini uses the big cap as a cheap and easy way to remove the dc bias on the audio output. Considering Eurorack has dual power lines, I'd definitely recommend going to down the route of using the opamp to bias the audio properly.  However you won't need the cap before that stage, you'd want it at the output, along with a 1k resistor, as Eurorack has a standard of  1k output impedance.
Attached is the Oscitron output stage for your reference.  Very similar to yours apart from I derived the 2.5V using a voltage ref. Hope this helps!

Fault report / Re: Very loud mains hum from audio out
« on: January 10, 2018, 10:43:04 PM »
Hi - I think this is just the internal audio cable that has come loose in the post.  It's very easy to reseat. Do the following:
1)  Undo the 4 screws to the base plate
2)  Reseat the blue cable connected from the 1/4" jack to the PCB
3)  Test it.  If working, do it back up.  If not working, try waggling blue cable while it's on and making sound and let me know if it makes any difference to the issue.

If this doesn't make any difference, email me on

miniAtmegatron / Re: Serial Monitor
« on: January 05, 2018, 06:36:11 PM »
Couple of questions:
What is the code you're adding to do the serial monitoring (Is it all using the Arduino in-built library?)
You'll need to add the jumper to the PCB so that it boots into Arduino mode rather than MIDI device mode.  The Serial Monitor won't recognize it when it is in MIDI device mode.  The positioning of the jumper is shown in the instructions.

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: January 05, 2018, 06:31:16 PM »
Ah yes - I've also had a few delivery issues over Xmas :(

miniAtmegatron Hardware technical support / Re: is this r22?
« on: January 05, 2018, 06:30:34 PM »
Ah yes you are correct! I was a bit surprised when they turned up without any bands, but I checked and they are the correct resistance. Unfortunately it wasn't possible to alter the instructions as they were already printed.

Everything else / Re: Midi controllers
« on: January 02, 2018, 11:21:07 AM »
Hi - It depends on the specific keyboard. 
If it is just requiring USB for power, you can use any decent 5V USB power supply with a USB cable (eg an iPhone charger). 
If it is using the USB for MIDI and power and it doesn't have any MIDI ports, you'll need a "USB MIDI Host".  This can be a 1) a computer or 2) a stand alone device.
For 1) Just connect the Atmegatron to a USB MIDI device connected to your computer and the USB keyboard keyboard to the computer.  Then use an app like MIDI Ox ( to route the keyboard to the USB MIDI device.
2)  You can get a standalone device like this to connect the USB keyboard to the Atmegatron or  There's also a few DIY projects out there if you want to make your own!

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: December 28, 2017, 01:26:36 PM »
Wow I didn't even know about that setting - that's bonkers!  I've located it and updated it to a luxurious 1Mb per pic!

Nice PCB - that's got me think about the possibility of an expander board that allows CV control over the parameters. I'd be tempted to put the Arduino serial pins (digital 0 and 1) on a 2 pin header that can be added as an option. This would then allow an expander unit to be connected which would provide more modular friendly inputs.  Use the 6 analogue inputs for CV and some of the free digital inputs for gates.  Then convert them to MIDI CCs which is transmitted over serial to the Euro-Mini.

I might even be tempted to develop that next year if there was a demand for Eurorack miniAtmegatrons! Def worth sticking 2 pads on the PCB for pins 0 and 1 (on a standard 2.54mm 2-way header).

Anyway, just a thought!

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: December 07, 2017, 06:20:39 PM »
Yes, that's work in-progress.  Still trying to find a way to publish it properly.  Also, I think there's possibly too many diagrams, it makes it look more complex than it is!
Start with the Min class.  That contains a hardware class and engine class. The hardware class handles the electronics, the engine is the processing for the generating audio.  Both of those classes generate events.  The job of the Min class is to pass events between the hardware and engine class.  The idea is that the hardware and engine can be totally independent, so you can port different audio engines to different hardware interfaces really easily.
R.e. your customisations.
a)  Yes totally possible. Even can use a Sparkfun MIDI shield (don't connect the buttons or pots though)
b)  You'll need to remove pots on A4 & A5 as they use the I2C bus.  Then add an external I2C ADC chip.  If you look at the code for the Oscitron Hardware, you'll see how to do this with a Microchip MCP3208 ADC.  So 8 of the pots will come off the MCP3208 and 4 off the Atmega328.  That frees up A4 & A5 to use for the I2C to drive the ADC.
c)  See above.  Just free up A4 & A5 and use the I2C bus.  Then adding an I2C screen at a later date is easy too!

Hope this helps as a starting point!

Atmegatron / Re: Any more Atmegatrons?
« on: December 05, 2017, 01:53:49 PM »
If you haven't already, join the mailing list for info on a very small number of Atmegatrons which will be available in a couple of weeks.  Info will only be available on the mailing list:
After they've gone, it's eBay only!!  There'll be more info on the new range of Atmegatrons in the new year. Aiming for launch at Superbooth.

miniAtmegatron / Re: Is Miniatmegatron open source?
« on: December 03, 2017, 11:13:27 PM »
Hi - I'll do a little chart showing how the classes all interact with each other.  It's pretty easy once you know this.  The .ino file is just a holder for uploading the project.  All the work is done in the classes now.   Will hopefully add the diagram tomorrow.

Software announcement / Libraries v2.9 released + other updates
« on: December 02, 2017, 05:14:13 PM »
Here's the other updates:
* Libraries v2.9 is released and on Github: This is for Arduino 1.8.5 (and Atmel 7 + Visual Micro should you desire!)
* miniAtmegatron and miniOdytron now have CC 7 for volume added to latest version
* miniAtmegatron and miniOdytron now have separate versions for issue 2 and 3 kits.  Unfortunately the issue 3 kits have different LED pinouts which require different software. You can see your issue number below the value inc button on the pCB

Software announcement / Strings v1.3 released!
« on: December 02, 2017, 05:05:27 PM »
Strings v1.3 has all parameters controllable via MIDI CCs:
1: LFO modulation depth
16: Phaser LFO waveform
18: Arpeggiator pattern
19: Arpeggiator clock division
20: Waveform 1
21: Waveform 2
22: Waveform 3
23: Waveform 4
24: Pitch envelope depth
25: Phaser source mix
38: Gate on/off
39: Pitch LFO invert
40: Arpeggiator ping pong
41: Phaser LFO invert
42: Tie waveforms on/off
43: Waveform cycler on/off
72: Env Release
73: Env Attack
75: Env Decay
78: Pitch LFO waveform
79: Pitch LFO clock division
80: Env Sustain
81: Phaser LFO clock division
82: Sine Phaser frequency
82: Cycler clock division
94: Osc detune
95: Phaser depth
123: All notes off

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