Dual VCO
My main audio oscillators use Music From Outer Space PCBs. There are two oscillators per module. I also added some additional circuitry for sawtooth doubling (octave up), dividing the square by two (octave down), and a shared PWM modulation input (CV mixer).
Aug 2024
- Upgraded graphics from hand drawn pen to ink jet printed sticker sheet.
- Left side has an issue with the square wave where it is making a ticking sound. Quick look on the scope shows glitching, narrow pulses mixed in with the expected wave. Will be troubleshooting…
- While testing with 16 step sequencer, I noted that the oscillator frequency latches up to 67 kHz when the CV input gets to high (see table below). It has to be dropped well below the latch up point before it lets go of the 67 kHz state. When observing with audio output, it just appears like the oscillator has stopped. Definitely not desirable behavior. Perhaps adding a clamp somewhere to limit the input will help. To be continued…
| CV input [V] | Frequency output [Hz] |
|---|---|
| -3.7 | 20 |
| -2.6 | 40 |
| -1.5 | 80 |
| -0.64 | 160 |
| 0.36 | 320 |
| 1.36 | 643 |
| 2.36 | 1300 |
| 3.36 | 2600 |
| 4.36 | 5930 |
| 5.06 | 12400 |
| 5.26 | 67000 |
Setup notes: coarse and fine controls centered, using exponential input; rough freq measure and this is prior to any calibration and a long time since any previous calibration
