MiniOSC v2.x

An analog oscillator based on the 40106 chip. It’s a remake of my very first PCB-based module. I added PWM and Sync inputs.

MiniOSC v2.0

I redid the PCB with SMD parts. In fact, I’m in the process of remaking my all my old PCBs into SMT. It’s just easier to keep the layouts clean while keeping the modules small.

MiniOSC v2.0 Back

I understand that this might make them not so beginner-friendly, so I’m also planning to do a new line of through-hole modules with bigger panels in the future.

The Panel

I’ve been expermenting with more handwritten labels and panel art using a drawing tablet that I got for free.

The MiniOSC v2.0 panel

I did my drawing on Inkscape, exported it to PNG, and then imported the PNG into KiCAD through the Image Converter. I only had to Export it to Clipboard and then pasted it into my PCB Editor.

The MiniOSC panel art on Image Converter

New Features

The first version of the MiniOSC had basic controls and I/O: Coarse and Fine Tuning knobs, FM CV, Pulse and Saw Wave Outputs.

With this new version, I decided to make some improvements. Testing out these mods was easy to do using 3D-printed panels and some deadbug wiring.

Testing mods on my MiniOSC version 1's

PWM CV and Triangle Wave Output

Pulse width on first version can only be controlled by a knob, which is pretty useless for my usual hands-off generative jams. This is why I felt the need to add a PWM CV input with an attenuator for better control.

MiniOSC v2.0's PWM input and knob

I also needed something smoother sounding than saw and pulse waves so I added a triangle output.

My deadbug prototype for the triangle output and PWM input

The upper half doesn’t always line up perfectly, but I don’t mind it.

The triangle wave output from the MiniOSC v2.0

The Sync Input

This simple mod lets me hard sync one oscillator to another for further tone shaping. This works especially great with the triangle and saw output.

In the final version, it can be enabled using a latching button.

MiniOSC's sync button
Triangle output from MiniOSC v2.0 synced with the pulse wave from another one

This can get LOUD. My tests can make it go to 20Vpp, so be careful.

Schematic

This isn’t too different from the original MiniOSC. Because I was able to switch to SMT, I don’t have to deal with pin sockets anymore.

The MiniOSC v2.1 schematics

PCB

My PCBs for this module were sponsored by PCBWay. Of course, everything’s open-source, so you can download all my files and modify/print them as you please.

NOTE: After I verify this version, I will put this module up for PCBWay’s PCB Assembly service where you should be able to order the boards with the SMD components pre-populated.

TitleFilename
Gerber FilesMiniOSC v2.1 - Main.zip
MiniOSC v2.1 - Front.zip
BOMMiniOSC v2.1 - Bill of Materials

Version Log

v2.1 - Fixed initial mistakes (For verification)

v2.0 - Moved to SMD

More Build Notes

This build uses two different types of potentiometers. Coarse Tune and Pulse Width use solid shaft, panel mounted, pots that also hold the panel in place. I use KN1250 ABS Fluted 15x11mm knobs for most of my builds.

Threaded pot

The Fine Tune, FM, and PWM controls use indicator pots that aren’t theaded. These are knurled and don’t need separate knobs attached to them.

Indicator pot

Trim pots come in different sizes even though they might look similar. Make sure to get the 3296W type to be sure that it’ll fit.

The sync enable button uses a latching KFC7x7 switch. You’ll also need to buy a button cap for it. I used red because it looked good with the matte black panel.

Latching button

I have links to all of the parts on the iBOM.

Conclusion

At the time of writing this, I am still waiting for my copies of the v2.1 PCB. So I haven’t verified my changes yet. I’ll update this page as soon as I’m done.

You can check out my Instagram @benjiaomodular or YouTube for demos.

Let me know if you’ve built it! Also, if you’d like to support what I do, please consider donating through Ko-Fi.