125B · 4 knobs

Lynch

Category: EQ / Filter
Controls: Freq · Mid · Low · Hi
Price: $10.00in stock

Buy the PCB at God City Instruments Build document

From the vendor

Active 3-band EQ

Lynch is an active 3-band, sweepable mid EQ circuit that can be built as a stand-alone pedal or used as a mod to add EQ control to another circuit. A volume trim control is also available on the front panel to compensate for any loss or boost in volume caused by equalization.

Sale is for PCB only. You must source the components and build the pedal yourself. To make foot switch wiring easier, we also suggest you buy the 3pdt utility switch.

Build documentation can be found here below. Please read before purchasing.

Lynch Build Guide

For your convenience, a parts kit can be purchased here:

http://smallbear-electronics.mybigcommerce.com/kit-lynch-pcb-not-included/

Share your work, get tips, ask questions and help troubleshoot at our Facebook Group. Don't forget to agree to the group rules if you wish to join. GCI DIY PCB builders group

NOT FOR COMMERCIAL USE

Schematic

The schematic is in the vendor's build document. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 52 rows

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Ref	Value	Normalized	Type	Notes
Resistors 22
CLR	4.7k	4.7k	1/4 watt resistor 1k-10k Current limit	ing resistor for LED.
R1	10K	10k	1/4 watt resistor
R2	2.2M	2.2M	1/4 watt resistor 1M Pull down res	istor
R3	2.2M	2.2M	1/4 watt resistor 1M Bias referenc	e for IC1A. Forms HPF with C2.
R4	1k	1k	1/4 watt resistor
R5	100k	100k	1/4 watt resistor
R6	10k	10k	1/4 watt resistor 1k-100k Affects range	of trim control. Smaller will will be louder, but more clipped.
R7	22k	22k	1/4 watt resistor 27k-47k Affects balan	ce of differential summing amp. R7-9, and R19 must match.
R8	22k	22k	1/4 watt resistor Affects balan	ce of differential summing amp. R7-9, and R19 must match.
R9	22k	22k	1/4 watt resistor Affects balan	ce of differential summing amp. R7-9, and R19 must match.
R10	10K	10k	1/4 watt resistor
R11	10K	10k	1/4 watt resistor
R12	10K	10k	1/4 watt resistor
R13	10k	10k	1/4 watt resistor
R14	10K	10k	1/4 watt resistor
R15	2.2K	2.2k	1/4 watt resistor 1k-10k Affects range	of frequency pot
R16	2.2K	2.2k	1/4 watt resistor 1k-10k Affects range	of frequency pot
R17	10k	10k	1/4 watt resistor
R18	10k	10k	1/4 watt resistor
R19	22k	22k	1/4 watt resistor Affects balan	ce of differential summing amp. R7-9, and R19 must match.
R20	3.3k	3.3k	1/4 watt resistor
R21	3.3k	3.3k	1/4 watt resistor
Capacitors 14
C1	1u	1u	Film cap
C2	22n	22n	Film cap 10n-0.1u Input cap. Fo	rms HPF with R3.
C3	1u	1u	Film cap
C4	100u	100u	Electrolytic cap 47u-220u Power filter	capacitor
C5	100u	100u	Electrolytic cap 47u-220u Power filter	capacitor
C6	0.1u	100n	Film cap
C7	470p	470p	MLCC 220p-1n Bigger darken	s the circuit overall.
C8	0.1u	100n	Film cap
C9	47n	47n	Film cap 22n-100n Affects low f	requency boost or cut. Should match C10.
C10	47n	47n	Film cap 22n-100n Affects low f	requency boost or cut. Should match C9.
C11	4.7n	4.7n	Film cap
C12	68n	68n	Film cap
C13	470p	470p	MLCC
C14	22n	22n	Film cap 10n-47 Affects hi fr	equency boost or cut.
Diodes 1
D1	1n5818	1N5818	Schottky diode 1n5817, 1n4001, bat 41, etc Any suitable	protection diode for 9v.
ICs 3
IC1	TL072	TL072	Dual Op Amp AD712, LM833, OPA2134 Any pin compa	tible dual op amp.
IC2	TL072	TL072	Dual Op Amp AD712, LM833, OPA2135 Any pin compa	tible dual op amp.
IC3	TL072	TL072	Dual Op Amp AD712, LM833, OPA2136 Any pin compa	tible dual op amp.
Potentiometers 4
FREQ	C50k	C50k	16mm dual pot B50k, C100k Frequency ran	ge or taper not ideal unless C50k is used
MID	B10k	B10k	16mm potentiometer
LOW	B100k	B100k	16mm potentiometer
HI	B100k	B100k	16mm potentiometer
Trimmers 1
TRIM	A100k	100k	16mm potentiometer
Switches 1
S	PAD	PAD	Send to PCB
LEDs 3
LED	L1	L1	LED
L+	PAD	PAD	LED+
L-	PAD	PAD	LED-
Other 3
R	PAD	PAD	Return from PCB
V	PAD	PAD	9v input
G	PAD	PAD	Ground