Tuesday, July 14, 2020


Germanium Diodes

I have a lot of NOS (New Old Stock) Russian germanium diodes that I purchased on eBay. I've used them in a few keyboards in place of the common 1N4148. They don't always fit as they are much larger.

I decided to make a board to highlight these large glass diodes.

The diodes are all moved to the top left of the board. In 4 clusters of 12. Each of the clusters is a row.

The board is a plain 4x12 grid layout. Powered by a Pro Micro. This one has the new Sparkfun Qwiic Pro Micro which has a USB-C connector.

I use a second PCB as the bottom. There are holes for M2 spacers and screws to hold the two PCBs together.

I installed Peel-A-Way sockets on the PCB. I did try installing them in the small top PCB as well but trying to get the leads to line up was next to impossible as the diodes would wobble in the sockets. Soldering them held them in place and made it much easier to fit all 13 pins in the socket.

The top PCB connects the Cathodes of the 12 diodes together. There is a 13th pin that connects the Cathodes back to the main PCB.

The WS2812B RGB LED is installed under the diodes. The dot indicates pin 1, which is the opposite corner of the notch on the LED.

Trimming the leads in a staircase pattern made it much easier to fit the top PCB. The leads were trimmed flush to the PCB and then soldered.

Here the bottom piece is the same PCB in black. I had already soldered a set with sockets before realizing how difficult it is to align all 12 diodes.

The grid of holes to the right of the Pro Micro are for small zip ties to secure the USB cable. I ran out of red ones, would use at least one more to secure the cable.

The matrix is identical to the Gnap. The WS2812B LEDs are connected to the same pin as on the Gnap RGB (Gnap with a WS2812B strip attached). The same firmware can be used, the only change needed is the number of RGB LEDs. 4 instead of 7.


I used the same 4x4 plate that I made for the unquadquad. The PCB also has the holes for PCB mount switches.

With some black keycaps.

Gerber files on git.