Cards 3 (Envelope Generator) and 4 (Pulser) can have problems with bleed into the audio. This is caused mainly by LEDs that take a lot of current. I cut the traces on bottom side to the driver transistors 2N1711 and soldered 1k resistors across the cuts to drop the currents. In card 3 I also added a 100pF capacitor across IC1 pins 12 and 14 to tame possible oscillations. Card 3 has two jumper wires.
Card 5 (Balanced Modulator) has seven vactrols. Vactrols 1/2, 3/4 and 5/6 need to be matched. With this simple test-circuit I measured the on-resistance of the LDR.
Resistance keeps rising as long as the LED is on. This is because the LED warms the LDR and this changes the resistance. I measured the lowest resistance when the vactrol was fired on. On REV2.1 cards there is a small pad added that indicates where the positive (+) lead of the vactrols LED should be inserted.
Ei kommentteja:
Lähetä kommentti