Build Guide - Calibration

Step 1 - LO-End :-

  1. Set the '5K Lin' pot fully anti-clockwise
  2. Set [FREQUENCY], [WAVE SHAPE] and [CV A] to their minimum (CCW) position
  3. Set [CV B] to ‘0’
  4. Monitor [SAW-DC]
  5. Adjust P101 for an output of 16Hz

Step 2 - Wave Shaper :-

  1. Set P201 to its mid-position
  2. Monitor [SHAPED DC]
  3. Adjust P201 for best sine shape which should be similar to that in Figure B. Note that the wave shaping circuitry can take a couple of seconds to stabilise so make small adjustments and wait for the waveform to stabilise
  4. Turn [WAVE SHAPE] to maximum and check that the waveform is similar to that in Figure C
  5. Repeat steps (3) and (4) until both ends of [WAVE SHAPE] are a best match for those in Figures B & C


Figure B

Figure C

Step 3 - HF Trim:-

Stage 1:

  1. Monitor [SAW DC]
  2. Set [CV-B] pot to '0'
  3. Set REFERENCE to 0.0V to [CV A]
  4. Adjust [FREQUENCY] for 300Hz using [CV-B] pot for fine tuning
  5. Set REFERENCE to 2.0V to [CV A]
  6. Adjust ‘5K Lin’ pot for 75Hz
  7. Repeat steps (3) to (5) for best accuracy

Stage 2:

  1. Set REFERENCE to 2.0V to [CV A]
  2. Set [CV-B] pot to '0'
  3. Adjust [FREQUENCY] for 300Hz using [CV-B] pot for fine tuning
  4. Set REFERENCE to 0.0V to [CV A]
  5. Adjust P102 for 1200Hz
  6. Repeat steps (1) to (5) for best accuracy

Calibration of the HF Trim is a series of successive approximations so stages 1 and 2 should be repeated several times for optimum accuracy.

Email:  elby-designs@bigpond.com
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