Homebrew SD Interrupter on strip-board
Posted: Sat Aug 15, 2015 12:30 am
Knocked up a strip-board version of the oneTesla SD Interrupter, the main differences being the use of an Arduino microSD card reader module and a contrast pot for the LCD. The rest of it is essentially the same as the original circuit. Using the microSD module eliminates the need for the 4050 chip in the original circuit, saving space and making construction a lot easier.
The various photos below show how it was put together with the ATMega328 and its support circuitry under the LCD, a 10k pot for the contrast, a jumper (to the right of the pot) to disconnect MISO/DO from the microSD card module during ISP programming (it won't work otherwise) and a 4xAAA battery holder mounted about 3mm above the board with the microSD card module underneath it. The underside of the board includes a surface mount low-dropout regulator (AMS1117).
The various photos below show how it was put together with the ATMega328 and its support circuitry under the LCD, a 10k pot for the contrast, a jumper (to the right of the pot) to disconnect MISO/DO from the microSD card module during ISP programming (it won't work otherwise) and a 4xAAA battery holder mounted about 3mm above the board with the microSD card module underneath it. The underside of the board includes a surface mount low-dropout regulator (AMS1117).