This guide is for all three Clock Tiles: Clock Generator, Clock Divider, and Clock Multiplier. They all use the same PCB with the same component values. The differences are in the pull-up / pull-down resistor and jumper placement, and the software running on the microcontroller.
The two sets of jumpers are used to configure whether the central 3.5mm socket is connected to the pot giving CV control of the pot function, or if it goes to a separate CV or gate/trigger input. Both sets of jumpers should be in the same position: either joining the top two pins (labelled “SEP. POT” on the PCB), or joining the bottom two pins. The Clock Multiplier uses no jumpers, and has the top two pins hard-wired. More on this later…
Although the PCB has a footprint for an SMD microcontroller, the DIP (on a socket) is much easier to program and reprogram. If using the SMD microcontroller programming can be done through the DIP socket, even on a fully populated PCB. The latest revision has a tact switch instead of the SMD microcontroller pads. The tact switch makes it easier to change operating modes from the front panel.
Be sure to get the MCP1702 and not the MCP1700 power regulator — the 1700 can only handle up to 6V input.
|1||B10k||Potentiometer||9MM SNAP-IN||9mm vertical snap-in pot, Alpha / Panasonic style with 6mm built-in knob.|
|1||1N4007||DIODE-DO214AC||DO214AC||Power protection DIODE|
|4||B54S||BAT54S Schottky Diodes||BAT54S_SOT23||Schottky barrier (double) diodes|
|1||Tact Switch||6×6 13mm||Tact Switch 6*6mm 13mm Through Hole SPST-NO||https://www.taydaelectronics.com/tact-switch-6-6mm-13mm-through-hole-spst-no.html|
|1||ATTINY85-20||DIP08||Atmel 8-pin 2/4/8kB flash uC|
|1||Header||1X01 Male||PIN HEADER|
|2||Header||1X03 Male||PIN HEADER|
|3||3.5mm Jack||THONKICONN||3.5mm socket for Eurorack modular synths||https://www.thonk.co.uk/shop/3-5mm-jacks/|
Now is also a good time to file away the “mouse bites” that separate the PCB and Panel.
Solder the surface mount devices. Each of the three modules uses different configurations of input and output pull-up and pulld-own resistors. Leave the unused spots empty.
If building the Clock Multiplier, the wire jumpers can be soldered in now. Bend a bit of discarded resistor lead into a U and drop it into the holes to connect those traces. Trim the leads flush on the other side so it won’t interfere with the socket later.
Trim the IC Socket pins almost flush to the bottom of the PCB so they won’t interfere with the potentiometer (they shouldn’t anyway).
Straighten the potentiometer “snap in” supports so that they can clear the DIP socket when being installed.
They may need to be flared outwards a wee tad.
Before soldering the pot double-check to make sure the DIP pins are contacting the metal body.
The power cable can be installed now.
Assuming no shorts, apply power and check that Pin 8 has 5V and none of the other pins have 12V.
If testing the Clock Divider or Clock Generator, add jumpers to the two sets of jumper pins. They should both go over the same set of pins: 1 and 2, or 2 and 3. Don’t put on jumper on 1-2 and the other on 2-3. The module won’t function properly without jumpers.
Add the appropriate programmed microcontroller, and power-up the module. The led should immediately flash to signal that it has booted and loaded any EEPROM presets without error.
Test all inputs and outputs with the jumpers (if jumpered) in both positions.
Bootloader: Attiny85 16MHz internal clock
Older source for PCBs without tact switch: