CA3240

Dual MOSFET-Input Op-Amp DIP-8 / SOIC-8.1 circuit uses this part.

Substitutes same socket

Parts that fit the same socket: the same function, pin count and pinout. The figures are read off each part's datasheet (this one's from page 2), typical where the sheet gives a typical value, otherwise the maximum. Closest first; the last column says what differs. A different part can change the sound, and a circuit may lean on one particular figure, so read the build document's notes before you swap.

This part

Part	Input	Supply	GBW	Slew	Noise	Iq	Boards
CA3240EZ	mosfet	4–36 V	4.5 MHz	9 V/µs	40 nV	4 mA	10

Dual CA3140: MOSFET inputs that reach 0.5 V below the negative rail, but about 4 mA per amplifier.

Fits the same socket

Part	Input	Supply	GBW	Slew	Noise	Iq	Boards	Differs
CA3260	mosfet, RR out	4–16 V	4 MHz	10 V/µs		4.5 mA	8	16 V max, not for 18 V; rail-to-rail output. CMOS output swings to both rails, but the 16 V supply limit rules out 18 V pedals.
TL072	JFET	4.5–40 V	5.25 MHz	20 V/µs	37 nV	1.4 mA	1338	JFET input. JFET input; inputs must stay 4 V above the negative rail, and the input range reaches the positive rail.
TL082	JFET	4.5–40 V	5.25 MHz	20 V/µs	37 nV	1.4 mA	72	JFET input. JFET input; inputs must stay 4 V above the negative rail, and the input range reaches the positive rail.
LF353	JFET	7–36 V	3 MHz	13 V/µs	18 nV	1.8 mA	73	JFET input. JFET dual; common-mode range must stay 4 V inside each rail.
TLC272	CMOS	3–16 V	4.5 MHz	21 V/µs	10.8 nV	0.56 mA	7	CMOS input; 16 V max, not for 18 V. CMOS dual limited to 16 V total; the input range includes the negative rail.
UPC4570	bipolar	8–32 V	15 MHz	7 V/µs		2.5 mA	5	bipolar input. Low-noise, wideband audio dual; needs at least ±4 V (8 V) supply.
NJM4565D	bipolar	8–36 V	10 MHz	4 V/µs		2.25 mA	2	bipolar input. Drives 20 V peak-to-peak into 400 Ω; the DIP8 (NJM4565D) is listed as discontinued.
M5218		4–32 V	7 MHz	3 V/µs		1.5 mA	21	Low-noise audio dual the maker calls close to the 4558 and 4559, with ±50 mA load current.
LF412	JFET	7–36 V	4.5 MHz	21 V/µs	18 nV	0.56 mA	4	JFET input. FET-input dual with standard pinout per the drawing (the 2026 pin table misprints pins 4 to 8).
4580	bipolar	4–36 V	15 MHz	5 V/µs		3 mA	103	bipolar input. Low-noise, high-output-current audio dual from ±2 V; the DIP8 (NJM4580D) is listed as discontinued.

Faceplate	Circuit	Based on	Category	Vendor	Box	Knobs	Price	BOM
	Fuzzhead FX MOuSeFET Vero Verified 2N7000 · CA3240 Fuzzhead Fx MOuSeFET	Fuzzhead Fx MOuSeFET	Distortion	Dirtbox Layouts	—	3	—	25