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===== Testing and Calibrating the VCF =====

==== Testing ====
  - Re-attach the power supply (with J4)
  - Apply 3volts to R90 (either with 2 AA batteries or a benchtop supply)
  - Probe the resonance pot with either a cheap pair of headphones or your oscilloscope.  With the cutoff all the way anti-clockwise, you should see mostly a sinewave.  If you're probing with headphones, you should hear a low, soft tone.  When you turn the cutoff up, you should see a waveform similar to the one you have selected on the VCO.  Using headphones you should hear a lot of higher overtones to the sound, and it might be buzzier and more 'acidic'.

==== Calibrating ====

According to the [[TB-303]] service manual, the resonance frequency should be at 500Hz.

  - Set the waveform to saw
  - Set Cutoff to 50%
  - Set Resonance to 100%
  - Apply 3V DC to the VCO (or press the lower C key if your sequencer is done)
  - Ajust TM3 so that the resonance frequency is 500Hz
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