A three-knob delay module based on Rene Schmitz' PT2399 delay design. It’s a simple setup with input and output sections designed to work with Eurorack modular synthesizer levels (10Vpp).

MiniDelay pcb fully assembled
MiniDelay perfboard prototype
MiniDelay front panel


Watch me talk about the module as well as some sound demos on Youtube.


Bill of Materials

Download the complete list of materials from my Github: MiniDelay v1.0 - BOM.xlsx.


The MiniDelay v1.0 schematic. Click on the image to see full size.


My PCBs in this series were sponsored by PCBWay – a great option for prototyping. Use their Quick-order PCB tool to get an instant quotation on the files.

PCB shops use Gerber files for etching copper traces, printing labels, drilling holes, and other manufacturing steps. You can download my zipped Gerber files for a version you like and upload those into their website.

This is also my very first SMT project!

MiniDelay module from the back


1.0. Initial version

This was the first release of the MiniDelay. I have tested this and didn’t find any issues. These come in two boards: The Front panel and the Main board. Make sure to print both.

SchematicsMiniDelay 1.0.png
Gerber FilesMiniDelay 1.0 -
MiniDelay 1.0 -
MiniDelay v1.0 - BOM.xlsx


There are a couple of other features I plan to do for future versions. CV inputs for most settings can be added. A dry knob or a wet output will also be pretty helpful.

This module does have some hiss/noise at longer delay times, as expected with PT2399 circuits. One workaround for this would be to cascade two PT2399 circuits together. I’m also considering this for v2.

For now, I’m pretty satisfied with how it sounds!

Let me know if you’ve built it. Follow me on Instagram for more updates @benjiaomodular.