Serge Voltage Variable Q VCF
Voltage controlled Filters (VCF)

Serge Voltage Variable Q VCF

Excellent general-purpose VCF offering simultaneous low-pass, high-pass, band-pass and notch (band-reject) outputs

Overview

Files

Bill of materials

Description

The VARIABLE Q VCF (VCFQ) is an excellent general-purpose VCF offering simultaneous low-pass, high-pass, band-pass and notch (band-reject) outputs. The resonance (Q) of this filter is dynamically variable by manual or voltage control. The VCFQ has two signal inputs. One incorporates an automatic gain control to prevent the filter from overloading at high Q settings. The second input has a level control so that the percussive effects of overloading the filter can be exploited. When a pulse is applied to the Trigger input, the filter will ring, producing a damped waveform similar to that produced by striking a resonant object.

Files

Project schematics / Serge Voltage Variable Q VCF
Title Version Creation date Copyright notice Software Download link
PCB (original version)

The original schematics was obtained from an open source at: http://www.elby-designs.com/webtek/cgs/serge/cgs112/cgs112_vcfq.html

0.9 1/30/2019 Serge Tcherepnin, Ken Stone DipTrace Schematics Download PDF
Control panel and its connections to the PCB

The original schematics was obtained from an open source at: http://www.elby-designs.com/webtek/cgs/serge/cgs112/cgs112_vcfq.html

0.9 1/30/2019 Serge Tcherepnine, Ken Stone DipTrace Schematics Download PDF

Bill of materials

PCB (original version)
# Value Quantity Designator Comment
Semiconductors
1 1N4148 5 D1, D2, D3, D4, D5
2 TL074 1 U1
3 TL072 1 U2
Resistors
1 1M5 1 R1
2 100K 11 R10, R13, R14, R20, R21, R24, R28, R3, R35, R8, R9
3 47K 5 R11, R15, R18, R25, R7
4 330R 6 R12, R16, R17, R19, R23, R34
5 220K 1 R2
6 15K 2 R22, R32
7 100K* 1 R26 R26: Usually not fitted
8 22K 2 R27, R29
9 110K 1 R30
10 2K 1 R31
11 100R 1 R33
12 330K 1 R4
13 150K 1 R5
14 1K 1 R6
Capacitors
1 220pF 4 C1, C13, C6, C9
2 100nF 3 C10, C3, C7
3 CX 1 C11 C11: CX, CY, CZ: Stabilizing capacitors. If you find you have high frequency oscillation occurring in your op-amps, fit 33pF - 47pF capacitors in these positions
4 CY 1 C12
5 0.1uF 3 C14, C15, C16
6 10uF/25V 2 C1n, C2n
7 1nF 1 C2
8 CZ 1 C4
9 22pF 2 C5, C8
Other
1 CGS108 3 CGS1, CGS2, CGS3
2 Bead 2 F1, F2
3 2.54/2P 5 J1, J4, J6, J7, J8
4 3.96-3P 1 J100
5 2.54/4P 1 J2
6 2.54/3P 2 J3, J5
Panel (original version)
# Value Quantity Designator Comment
Resistors
1 47k 1 R1
Variable Resistors
1 50k/Lin 4 VR1, VR2, VR3, VR4
Other
1 2.54/2P/Female 5 J1, J16, J17, J18, J9
2 2.54/4P/Female 1 J10
3 4mm Banana In 10 J11, J12, J13, J14, J15, J2, J3, J4, J5, J6
4 2.54/3P/Female 2 J7, J8
Switches
1 DPDT [ON-ON] 1 S1
Authors:
Serge Tcherepnin
Serge Tcherepnin

American composer and electronic-instrument builder

Ken Stone
Ken Stone

Australian Musical Instruments Designer

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