Tag: guide




here we are ….

We both decided to meet each other here.

Somewhere in between time, space & room.

As you´re accepting the challenge to assemble SPROOM i´m trying to give you everything you need for a successful ride.

For SMT projects i´m not giving step by step based instructions like for THT as my commercial versions come assembled with the most common parts.

Don´t worry! The DIY version is proven to be working 😉 (Props to My_Modular_Journey)

BOM overview:

Need to know

  • Depending if you´re a baker, heat plater, hot flower or poor iron man, you should consider a further step based assembly!
  • The mainboard is the only PCB with SMT parts on both sides. (FV1 chip) so you can possibly run into some reflowing issues, depending on your technique. Therefore i´m advicing to attach the FV1 chip at least and in best case just with an iron.

HINT: i´m using hot air technique and nether managed to reflow parts on the backside 😉

  • The LED´s of the control pots are very bright if using clear super bright LEDs. Due to a mystery it´s not possible to drop the brightness with changing resistor values. In this case i´m advicing to use common diffused ones with lower brightness.
  • For C1 & C2 i´m highly advicing to use C0G caps as they´re a sensitive part at the incoming audio path.
  • Regulators you should go for this one or similar.

EEPROM programming

All right, your SPROOM is already working with the internal 8 algorithms.

Now let´s figure out how to program the EEPROMs.

There are several methods to flash em. I´ve chosen an Arduino Uno as EEPROM burner.

You can use the already prepared codes for both ROMs or create own sets of algorithms with the SpinASM assembler.

What you need:

  • Arduino Uno (possibly anyone instead of Nano)
  • Arduino IDE and basic understanding on how to upload codes
  • Breadboard or the “NoisyFruits Arduino UNO programming HAT ISP_2432_OLED”

The Process

You can use the already prepared codes for ROM1 & ROM2, or dive deeper into creating own sets of algorithms.

Here´s how you wire up the chip with the Arduino. You can also use the 5V source for this …

With the SpinASM Assembler you can create or modify algorithms (the super nerdy way) or you can create custom sets of existing algos (the not so but still nerdy way).

It´s about exporting the set of algos into a hex file / code and importing / exchanging it into the ROM.h from the Arduino code.

Make sure you set the output directory where you want the file to be exported. You just need the source file.

Open the source file with a simple text editor and you will see blocks of cryptic hex codes.

Each of these blocks stands for one algorithm. If you get the text formatting and the file name correct with outputting it out of SpinASM you could simply copy the whole text. BUT i´ve never figured out how to format the source file to simply copy & paste it.

That´s why you need to copy & paste the 8 blocks of hex code by hand without that prefixing:

const unsigned char ROM_00[] PROGMEM = {

Do a compile check if the IDE likes what you´ve done and simply upload that code to your Arduino.

Now the Arduino flashes the EEPROM on each repowering, even without the IDE.

With checking the serial monitor @9600 Baud you will see this:

YOUR EEPROM is flashed and ready to go 🙂

If not take a banana and check your head.

If you figure out how to make the process of flashing EEPROMs easier let us know!

Manual Latching Switches DIY Guide

Manual Latching Switches DIY Guide


  • Thonkiconns (Mono or Stereo) Yes, it can handle stereo signals, the DIYers easter egg 😉
  • DPDT Switches 7x7mm –> ALI, Ebay
  • Caps 6mm outside / 3,3mm inside –> ALI , works with rectangle or round holes 😉

The assembly is pretty self explaing if you know how to place the buttons :p

The orientation matters!!! Take a look onto the side parts of em, the side with two holes -> II <- shows to you, or the bottom of the PCB.

As the button holes of the panel are very precise i´m advicing to solder the buttons at last with mounted panel. So you can make sure they glide softly.

1U instruction

You will quickly realize something´s different here this time …

The thonkiconns share their ground pins and this makes em sit very tight and uncool.

To make sure they sit where they should, place em all as good as possible, solder the middle pin of each, put on the panel or better to say squeeze on the panel and reheat the soldered pins. This will force em to get the right position. I´m sure you will get the myth behind 😉

Happy switching 🙂



Best you check the iBOMs for collecting parts! I´m not using any exotic parts, mostly common stuff 😉

All pots are linear “B”


Step 1 – Resistors (Mainboard)

Follow the BOM and its designator “R”. You see, i´m using vertical allignment to save some space. Orientation doesn´t matter.

Step 2 – Capacitors

You got metal film, electrolytic and a polystrene one. Make sure you flatten down the electrolytic ones, else you will have a bad time with attaching the panel! The poly cap can be a metal film as i´ve already seen. This guy is meant to keep tuning stability with changing outer temperature. I think if you don´t travel from the sahara to the north pole constantly, a metal film will be fine.

Step 3 – IC Sockets

You can mount ICs directly to the PCB, but i´m highly not advicing to! You will find a mark on the PCB to place the right orientation. Make sure they sit plane and tight where they should. First solder two outer legs and check the fitting. SOCKETS CAN SAVE YOUR LIVE(time) 


Step 4 – Pin Connectors & Power Header

The 2×8 headers must be mounted in between the PCBs. Which one is female or male doesn´t matter, but make sure you attach them plain and straight.

The 2×5 power header MUST be soldered on the other side! If you use a shrouded one check the orientation!

Step 5 – Trim Pots

The footprints are for 3296X, if you use 3296W flip the orientation. Else the trim pots will work inverted!

Step 6 – Pin Connectors (Component Board)

Before soldering squeeze the two boards together to make sure the headers correspond together! AND put them on the correct layer!

Step 7 – LED and Resistor

Ok, that´s easy … if you put the long leg of the LED into the round hole … :p

Step 8 – Potentiometers

Finally some fun parts 🙂

Due to my chosen design the fine tune pot is a T18 shaft. For the course pot i´m using a 19mm knob. Make sure they´re all placed clean. First solder one leg of each to see if they sit well.

Step 9 – Thonkiconns

I´m placing the thonkiconns as final step with attached panel. This way there is no glitch that issues the smoothnes of the Song Huei pots and the panel fits softly.

Step 10 – Final Assembly and checking (unpowered!)

So, here we are. If everything went fine this unit should already do its oscillator thang. If you have placed the ICs 😀

BUT, before powering check the power pins if there is any short!

After powering the LED should glow and nothing should smell like fried banana!

Step 11 – Tuning (the painful process, not …)

Don´t worry! But you want your oscillator to act in a musical manner, don´t you …!? 🙂

The tuning process of this circuit is “always” the same. Before explaining this for the 1.000.000 time, i´m giving you some content on the hand. Once you got it becomes simple.

All you need is a source that gives CV notes, something like a beatstep or any other sequencer that gives quantized CV. And a tool to measure the frequency of the outputs, something like an OT1 or a Mordax Data or a guitar tuner with audio input. (Euroack Level 🔥!!!)

The clue is to get it stable over 6 octaves at least. This unit should give 7 octaves minimum 😉

Additionally you got two trim pots. One for the initial center position of the course knob. One for the range of the course knob.

With the “octave trimmmer” you can set individual octave sweeps when fully turned up or down 😉

Happy Oscillating 🙂