Signal Gate circuit diagram, Part A and Part B. Resistors shown with three significant figures are 1%, 1/4-watt carbon film. The remaining resistors are 5%, 1/4-watt carbon. All capacitors in pF units are either ceramic COG types or dipped silver mica. Polarized capacitors are 50 V tantalum. Rail 0.1uF bypass capacitors are ceramic Z5U; the remaining capacitors are 50 V film. Trimming pots, P1 through P5 are 6-mm cermet. Voltage levels shown at each trim pot are approximate initial settings prior to final adjustment; see text. Parenthesis-enclosed bold letters ((A), (B), etc) designate points where waveforms may be found when the Signal Gate is driven by the Simulator. The U1 Substitute, a 100-ohm resistor mounted on a 14-pin DIP header plug, replaces U1, a 4066, when the Noise Gate is not used. Note (Spring 2001): U1 substitute resistor connection corrected to between pins 9 and 8. Also, power supply voltage to U11 is +5 volts.