Thursday, September 17, 2020

Gherkin Express TH

Credit Card sized through hole component Gherkin

This shares the same V-USB parts and configuration as the Aardvark and the same matrix and firmware as the Gherkin Express 2.

The main PCB is the standard 1.6mm thickness. The top and bottom plates are 0.8mm thick. JLCPCB will do 0.8mm in other colors for cheap, 0.6mm is only cheap in green soldermask.

The ICSP header is the tallest part. I built one with it to test, but have omitted it from the others so I could fit the top.

The holes in the top are 4mm for the switches and 3mm for the LEDs. The RESET and USBASP switches are shorter than the others.

With a full size socket and the 6.5mm tall resonator 8mm spacers were needed to fit the top piece. 9.5mm tall switches were used.

The lowest profile possible with 4mm spacers. 7mm tall switches are used. No socket for the ATmega328 and the resonator and power capacitor are replaced with the SMT parts from the Gherkin Express.

I use a 1.6mm thick brass nut as a spacer for the bottom piece. The bottom of the switch pins were trimmed. On the full height it has two 1mm thick nylon washers.

I will try replacing the resonator with a miniature through hole crystal and a smaller power capacitor.

Same outer dimensions as the Gherkin Express and Gherkin Express 2.