PMFoundations Clock User manual

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Clock v1.0 –Assembly Guide
Thank you for purchasing this module! This is an easy build with some precision integrated circuits.
Some of the pads are quite small and you will need a chisel tip or screwdriver tip soldering iron and
the skill to solder these tiny joints.
The module is designed and sized for Eurorack systems. You will need a 16-10 pin eurorack power
ribbon connector with –12/0/+12 which is connected to a synth power supply.
Follow the parts lists, these instructions and the PCB silkscreen text to build the module.
The module consists of 1 PCB board and a front panel.
You must follow the order of assembly as described below since some components will be soldered
underneath other components.

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Constructing the board
1. Resistors
See the appendix for options before proceeding.
Install the flat resistors on the TOP of the board. Solder and clip the leads.
2. IC Sockets
Now Install the sockets on the TOP of the board. Observe the notch or mark on the sockets and
align with the notch or mark on the board. Solder.
3. Power socket

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Install the 10 pin power socket on the TOP of the board. This must be installed with the correct
orientation or the module will be damaged when the power is connected.
The cut-out in the socket should face the jacks, aligning the cut-out with the "10" marking on
the board as shown in the photo. Solder on the underside.
4. Ceramic/film/polypropylene capacitors
With the capacitor values suggested in the BOM, the approximate clock frequencies are:
HI: 1.35 Hz to 68 Hz
LO: 0.1 Hz to 6 Hz
DO NOT INSTALL C3, C4, C5. See the appendix for options before proceeding.
Install the ceramic/film capacitors on the TOP of the board. Solder and clip the leads. The
photo shows one 2.2uF capacitor in bank 1 and four 10uF capacitors in bank 2 to make 40uF.

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5. Transistors
Install the transistors on the TOP of the board. These are polarized components. Align the
outline with the outline on the board. They should be raised off the board surface slightly and
at the same height. Solder and clip the leads.
6. Electrolytic capacitors
Install these on the TOP. Make sure you orient these capacitors correctly. The longer lead
and/or the lead marked with a + needs to be inserted into the hole that has the “+” marking
near it. Leads marked with “-“ go in the board hole WITHOUT the “+”. Solder and clip the leads.

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7. Trimmer resistor
DO NOT INSTALL R16 unless you are modifying the standard design according to the appendix.
8. LEDs
Install the LED on the TOP of the board and solder on the underside. The LED should face the
edge of the board. (photo in section 11)
9. Potentiometer
If the pot has positioning lugs on the front, cut these off with a sharp pair of flush cutting pliers.
The front of the pot (where the shaft protrudes) needs to be flat.
Tack one pin only with solder. This will be finalized later. Please ensure they are on the
CORRECT SIDE OF THE BOARD. See Photo in section 11
10. Switches
The locking switch is for the range HI/LO and the momentary switch is for the start/stop.
Tack one pin of the switches, align with the front panel, then solder all the remaining pins and
the locating lugs. (photo in section 11)
11. 3.5mm Jack Sockets
Tack one pin of each only with solder. These will be finalized later. Please ensure they are on
the CORRECT SIDE OF THE BOARD.

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12. Alignment
1. Place a washer over pot shaft.
2. Place the front panel over the board so that the pots and 3.5mm jacks align with the holes in
the panel.
3. Put nuts on the jacks and pots and FULLY TIGTEN all of them. Do not overtighten!
4. Now fully solder as many pins as you can reach of each jack and pot.
5. Remove the front panel and solder all the remaining pins on the jacks and pots.
6. If you cut off the ends of the pins of the jacks, near to the solder joint, the module will be
easier to fit into your rack close to other modules.
13. If you do not trust all your soldering and connections, carry out the voltage tests below before
installing the remaining ICs
Voltage tests

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1. You do not have to do these tests if you are completely happy with your soldering and are sure
there are no bridges or incorrectly placed components. However, these tests will ensure that
the correct power supplies are sent to the IC pins to ensure they will not be damaged on power
up.
2. Plug in the power supply and connect the –VE probe of a multimeter (set to the 20V DC range)
to one of the GROUND pins of the jacks. The GROUND pin is nearest to the edge of the board.
3. Check the voltage at the following points on the board:
a. At IC1 pin 14 approx = +12V
b. At IC1 pin 7, 12, 13 = 0V
c. At IC2 pin 14 approx = +12V
d. At IC2 pin 3, 5, 7, 8, 10 = 0V
e. All other pins should not show anything close to +12V or -12V
4. If any of these tests fail to match the readings given, you should check the components and
soldering before progressing
Final Assembly
1. Place the ICs in place by aligning the notch with the notch graphic on the PCB Silk Screen and
notch on the sockets.
2. Install the knob.
3. Put the caps on the switches by pushing each cap until it clicks.

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Appendix 1: Build options
Pulse level:
R14, R15 and/or trimmer R16 set the clock output pulse voltage level. The following options
are suggested:
•STANDARD BUILD: 10V pulse: R14 = 1.2K, R15 = 11k, R16 OMITTED
•5V pulse: R14 = 1.8K, R15 = 1.5k, R16 OMITTED
•VARIABLE PULSE LEVEL: R14 = 1.5k, R15 OMITTED, R16 = 50k Trimmer
Remember to add the trimmer to your parts order if you are installing this option.
If you are using R16, install it and then R15 SHOULD NOT BE INSTALLED. Make sure the multi
turn trimmer is oriented so that the screw is above the circle on the silk screen.
Range:
C3-C6 set the HI range of the clock and C7-C11 set the LO range of the clock. Each range is
determined by a bank of parallel capacitors equivalent to C(HI) and C(LO).
The clock values can be determined by entering different values for C in the range calculation
spreadsheet inclued in the documentation link.
Simply enter capacitor values in column A to find clock frequencies in columns D-E
For more extensive customization you can change the values of R1 and VR1.
The spreadsheet uses the following formula:
F = 1/2.2*(R4 +VR1)*C in Megohms and microFarads. F (freqency ) is the inverse of the clock
period.
You can use one ar more of the capacitors in each bank to obtain the equivalent values required
With the capacitor values suggested in the BOM, the approximate clock frequencies are:

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HI: 1.35 Hz to 68 Hz
LO: 0.1 Hz to 6 Hz
Calibrating the output voltage
If you have installed R16, connect the power supply and adjust the clock to a high frequency. Monitor
the output of the clock on an oscilloscope.
Alternatively, use a multimeter with the voltage set to a DC range that will read about 0-12V. Set the
clock to a slow speed if using a multimeter.
Adjust the trimmer until the desired voltage for the clock is achieved.