Boss NF-1 Noise Gate pedal schematic diagram
The Boss NF-1 Noise Gate pedal contains a simple circuit that cuts off all sound as soon as the signal level falls below a threshold level adjusted with the SENS knob. You can set how fast you want the sound to disappear with the DECAY pot.
Fig. 1: Boss NF-1 Noise Gate guitar pedal schematic diagram
Fig. 2: Boss NF-1 Noise Gate circuit board
Fig. 3: Boss NF-1 Noise Gate adjustment
- Controls: Sens, Decay
- Connectors: Input, Output, AC Adaptor
- Input Impedance: 220kΩ
- Output Load Impedance: over 10kΩ
- Maximum Output Voltage: +9dBm
- Current Draw: 3.9mA (DC 9V)
- Recommended AC Adaptor: ACA Series
- Dimensions: 70(W) x 55(H) x 125(D)mm
- Weight: 400g
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.
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