Free Modular

Clock Assembly Instructions

See general assembly instructions


See general components notes for more info about acquiring parts.

Interactive BOM: front, back

Board Reference Part Value Source Comment
Front R1-R8 Resistor 1kΩ   Determines output impedance. Any value is fine.
Front R1-R8 Resistor 5kΩ-10kΩ   Determines LED brightness. You may want to use a different value if you have different LEDs. A lower value means less resistance and brighter LEDs
Front D1-D8 LED 3mm   Any standard 3mm LED will work here.
Front SW1 Rotary Encoder EC11 series amazon  
Front SW2 Push button D6R30 F1 LFS DigiKey Make sure to line up the flat side of the button with the silkscreen on the PCB.
Front Screen OLED display SSD1306 SPI ebay The underlying display controller is the SSD1306. There are many ebay/amazon sellers that make modules based on it. Make sure to get one that uses the SPI protocol (6 or 7 total pins) instead of the I2C protocol (4 pins). The pins may be labelled differently or be in a different order on different modules. Just connect them to the corresponding holes on the PCB. The module also may or may not contain a 7th RESET pin. Either way should be fine. Different modules may also vary in the layout of their mounting holes. The faceplate is designed for a 23.5mmx24mm bolt pattern, which seems to be common, but it could be easily modified to fit a different screen. You can connect the screen to the PCB by soldering each wire individually or by soldering on some kind of 7-pin plug.
Front J1-J8 3.5mm Jack THONKICONN (a.k.a PJ398SM or PJ301M-12) thonk  
Front J9-J11 Pin headers 1x4, 1x4, 1x11 amazon Solder the two boards directly together using the male headers or (recommended) make them detachable using a male/female pair.
Back C1 Capacitor 100nF   Optional. Power supply noise filtering capacitor
Back C2 Capacitor 10uF   Optional. Power supply noise filtering capacitor
Back A1 Arduino Nano v3.0    
Back J9-J11 Pin headers 1x4, 1x4, 1x11   Match corresponding headers on front PCB
Back J12 IDC connector 2x8   Eurorack power header. Can use two rows of male pin headers or (recommended) a shrouded connector.
Back J13 - -   Not used. Expansion points for future features
Front - Mounting bolts 2 M2x8mm, 2 M2x16mm, 6 nuts   Used to attatch the screen to the faceplate. The two longer bolts can pass through to the PCB using additional nuts to hold everything together more firmly.