Quantisise has four outputs per section (VCO, VCA and two S&H outputs). Each is monitored by a different color LED, green for the VCO, yellow for the CV S&H, red for the ‘castle’ S&H, and orange for the VCA. After consulting with the wigglers, I realized that the objectives for the LED driver were as follows:
- A wide a range of brightness to indicate the levels up to 5 volts
- Low current with high intensity
- Isolated from the main power supply
Ken Stone’s CGSLD boards, which come in strips of eleven, were separated into six groups of four. An assembled set of four is shown above. High intensity, water clear LEDs are soldered into the board in a pattern that matches up to the panel holes. The boards are held in place behind the panel by the LEDs after they are inserted into the lenses. (The lenses are also from Mouser, e.g. the red one is part number 593-3000R.) The white leads are the input wires. Red and black wires are for power and ground. (Power and ground must be jumpered across the boards.) Note that R2 is soldered to the emitter lead above the board, since this is a circuit enhancement to increase the effective brightness range.
In the schematic, below, the 1N4148 diode protects the transistor from negative voltage on the input. Resistors R1 and R2 were selected experimentally, so that the relative brightness of the different colors is similar (to my eye). LED power is isolated from the 15 volt supply by a 12-volt regulator and some big capacitors.