Building the VCF Tile

Notes:

• IF THE PCB VERSION IS NUMBERED “108” OR HIGHER SEE THIS PAGE FOR INSTRUCTIONS.
• The following picture shows where values are changed from what’s printed on the PCB (in yellow).
• The 330 and 240 ohm resistors labelled below control the resonance gain, and are very tweakable. Some other values are on the schematic. These 330/240 values seem to work best.
• 2n7002 MOSFETs are optional. They provide a less aggressive, smoother distortion to the resonance circuit, but the effect is not very noticeable.
• The orange parts are optional.
  • Xn is a filter in the resonance gain section.
  • Trim resistors replace the trimmer pots. These trimmers set the CV range so that full use of the filter is between 0 and 5V. Resistors instead of trimmers will be fine unless you plan to experiment with other component values.
  • 2K resistor is to add a log curve to a linear resonance pot. Not needed as a linear pot is fine.

BOM:

Schematic:

Build Instructions:

If necessary, separate panels carefully by gently flexing and twisting back and forth, ensuring that they break cleanly at the “mouse bites”. File the leftover tabs down until flush with the edge of the panel or PCB.

Clean PCB with isopropyl alcohol to remove any manufacturing residues.

Begin by soldering the surface mount devices.

Ensure the diodes and ICs are in the proper orientation.

If not installing the trimmers, install the labelled “trim” resistor instead.

Add the male and female headers.

It doesn’t matter which PCB get the male or female headers, just that they’re on the right side. The sides with the surface-mount components face the same direction (downwards when module is installed), and the PCB with most of the components is on the “bottom”. Use this picture as a guide.

Before adding the remaining parts, trim flush the bottom header pin under the left-most 3.5mm jack.

Trim the top header pins on both sides if they interfere or make contact with the pots (they shouldn’t).

Solder the pots and jacks to the PCB. It’s useful to use the front panel to ensure they’re soldered flush and aligned.

Testing and Configuration:

Check all connections for shorts, particularly solder-bridges between IC pins.

Before applying power, check for shorts on the tile power connector.

Set both trimmers to the middle position (if using trimmers).

Apply power and check that none of the components are getting hot.

If using trimmers, turn frequency knob up full, put a multimeter on each of the test-points near the trimmers, and set the trimmer to the voltage indicated next to the trim point. -200mV for the left trimmer, and +400mV for the right trimmer. Within 50-100mV is okay. These trimmers set the CV range so that full use of the filter is between 0 and 5V.

With nothing connected to audio input or CV input, listen to module output with resonance turned full right. Feedback should occur just before the end of rotation with a steady tone. Sweeping the FREQUENCY control should change the frequency from very low to very high.

Connect an audio source and a CV source and check that these inputs work.

Done!