Ray Wilson authored this content while he was actively running MFOS as the founder and resident genius.
We retain the content because it reflects a valuable point of view representing that time and place.

Article by Ray Wilson

Guitar to Gate

This is a decent guitar to gate circuit. It sustains well on most notes. It takes you guitars signal and applies a gain of 100 to it then full wave rectifies it dropping the rectified signal on C3 charging it rapidly. When the guitar note dies the cap discharges via R13. U1-C is a comparator which goes high when the guitar's strings are played in response to the charge on C3. R7 and R8 set the threshold voltage for comparator U1-C. LED1 illuminates when the gate output is high. U1-D is used to provide some gain to the instrument applied to the input so that it will be high enough in amplitude to put through your VCF, VCA, etc. You could build this circuit on a small breadboard or stripboard.

 

Guitar to Gate Project Parts List

Qty.	Description	Value	Designators
1	LM324 Quad Low Power Op Amp	LM324	U1
2	Diode 1N914	1N914	D1, D2
1	LED	LED	LED1
2	Potentiometer	100K	R2, R14
2	Resistor 1/4 Watt 5%	100K	R5, R8
5	Resistor 1/4 Watt 5%	10K	R3, R10, R12, R17, R18
3	Resistor 1/4 Watt 5%	1M	R6, R13, R16
1	Resistor 1/4 Watt 5%	3.9K	R9
1	Resistor 1/4 Watt 5%	4.7M	R1
2	Resistor 1/4 Watt 5%	470K	R4, R11
1	Resistor 1/4 Watt 5%	47K	R15
1	Resistor 1/4 Watt 5%	82K	R7
1	Capacitor Alum. Nonpolarized	10uF	C5
2	Capacitor Alum. Nonpolarized	1uF	C1, C4
1	Capacitor Ceramic	.01uF	C3
2	Capacitor Ceramic	22pF	C2, C6
1	Capacitor Electrolytic	100uF	C8
1	Capacitor Electrolytic	470uF	C7
3	Jack 1/4" 2 Terminal		J1, J2, J3