BOSS NF-1 Noise Gate

ICs, transistors and diodes used in the Boss NF-1 Noise Gate pedal:

• IC1: uPC741C (operational amplifier IC)
• D1: RD11EB (11V Zener diode)
• D3, D3: RD4.7EB (4.7V Zener diode)
• D4-D8: 1S1588 or 1S2473 (switching diodes)
• Q1, Q2: 2SC732TM-GR (NPN silicon transistors)
• Q3: 2SK30A-Y (N-channel JFET transistors)
• Q4-Q9: 2SC1815-Y (NPN silicon transistors)

Adjustment procedure:

1) Set the Sens knob fully counterclockwise and the Decay knob fully clockwise.
2) Connect an oscilloscope to the effect's output through a millivoltmeter. Feed a 1kHz -45dBm sine signal to input.
3) Adjust VR3 and VR4 for the values shown in Fig.3.