x0xb0x Fabrication Manual: VCA
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The VCA can either use the BA662 or BA6110 chips. The kit comes with BA6110, which means that Q1-4 are also required. If you decide to go with a BA662, do not solder in Q1-4! Also, each chip has a different pinout so use IC15B for BA6110 and IC15A for BA662.

Dont put in your BA6110 upside down: the notch in the chip goes at the end of the socket that has a tapered end in the silkscreened picture (pointing north as seen above).

  1. Connect power from the IO board and provide 2.0VDC to R90, as before.
  2. In a quiet room, connect up a pair of low-fi (32ohm or greater impedance) headphones as before: ground the sleeve, and use the tip for probing. Touch the tip to rightmost pin (the one that is not connected to the ground plane) of where the volume potetiometer VR8 will go.
  3. Connect up an alligator clip as it was for testing the gate (clipped to R146) and touch the other end to R3 to generate a gate pulse. You should hear a struck note! Hooray, you're basically done with the analog section of the synthesizer!


1N4148 3 D27, D35, D36
100 ohm 5% resistor 2 R130, R132
2.2K 5% resistor 5 R125, R126, R124, R133, R162
22K 5% resistor 3 R120, R129, R134
47K 5% resistor 2 R119, R127
100K 5% resistor 1 R122
220K 5% resistor 3 R121, R128, R131
1.5MEG 5% resistor 1 R123
50K B (linear) potentiometer 1 VR7
.01uF (2A103K) capacitor 2 C21, C20
.033uF (2A333K) polyester capacitor 1 C36
.1uF (2A104K) capacitor 1 C41
1uF electrolytic capacitor 1 C38
1uF (105) tantalum capacitor 1 C42
10uF electrolytic capacitor 2 C37, C40
2SA733P, TO-92 PNP transistor 3 Q1*, Q2*, Q31
2SC536F, TO-92 NPN transistor 3 Q3*, Q4*, Q32
BA6110 9-SIP 1 IC15B*
BA662A 9-SIP 1 IC15A*
May 17, 2011 20:07