Obtaining Parts

Kits and components for your MFOS projects can be found at Small Bear Electronics and SynthCube.

The potentiometers can be rated for 1/4W and the parts list will say whether it should be log or linear taper. All components need to have leads. Be sure you are not buying surface mount parts.

Resistor Color Chart For Resistors Used In This Circuit

The resistors should be carbon composition or carbon film.
Use 1/4 watt resistors because 1/2 watt will be too big for the board.

Capacitor Markings For Caps Used In This Project

All capacitors should have a minimum 16V rating. There really is no maximum voltage rating but capacitors get larger as the voltage rating goes higher. I suspect that electrolytics rated at 25V, 35V or even 50V will still be small enough to fit the board. For ceramics the voltage rating can be much higher. The voltage rating is NOT CRITICAL except that ALL CAPS SHOULD BE AT A MINIMUM rated for 16V. The lead spacing for most caps on the boards from MFOS is .2" but you can always make leads with smaller (or larger) lead spacing fit so that is not a big deal.

Capacitors manufacturers have a variety of ways of marking the values on the components. When a cap is not plainly marked as .1uF (spoken as "point one microfarad") it will be marked in picofarad style. It will be marked like this: 104 which means 10 followed by 4 zeros picofarads. or 100,000 picofarads (or .1uF)

When capacitor values fall into a certain negative power of 10 they are given prefix names. Typically micro and pico with some folks occasionally using nano. So if a cap has the value of .0001 Farad we say it is 100 microfarads (or uF).

	milli	micro	nano	pico
.	000	000	000	000

If a cap has the value of .0000001 Farads we say it is .1uF (point one micro farad) but you could also say 100,000 pico farads, or 100 nano farads and be correct. You can see how the marking "104" takes up less space and space is at a premium on small parts.

So... with all that said .01 uF will be marked as 103 (10,000 pF) and 330 pico farads will be marked as 331. The next time you look at a cap I hope you are better able to tell it's value.

More information

• Basic Capacitor Information
• Reading Resistor Values
• Know Which Switch Is Which

Envelope Follower Project Parts List

Printable Parts List

Qty.	Description	Value	Designators
1	LM13700 Dual gm OpAmp	LM13700	U3
1	TL072 Dual Op Amp	TL072	U2
1	TL074 Quad Op Amp	TL074	U1
2	Transistor PNP 2N3906	2N3906	Q1, Q2
2	Diode 1N914	1N914	D1, D2
5	Carbon comp (or film) resistor 1/4W 5%	100K	R1, R3, R7, R8, R11
1	Carbon comp (or film) resistor 1/4W 5%	120K	R23
1	Carbon comp (or film) resistor 1/4W 5%	15K	R22
2	Carbon comp (or film) resistor 1/4W 5%	1K	R24, R25
2	Carbon comp (or film) resistor 1/4W 5%	1M	R4, R6
1	Carbon comp (or film) resistor 1/4W 5%	200 ohm	R26
6	Carbon comp (or film) resistor 1/4W 5%	20K	R13, R14, R17, R18, R20, R21
2	Carbon comp (or film) resistor 1/4W 5%	2K	R12, R15
3	Carbon comp (or film) resistor 1/4W 5%	300K	R5, R10, R16
3	Carbon comp (or film) resistor 1/4W 5%	30K	R19, R30, R31
2	Carbon comp (or film) resistor 1/4W 5%	4.7K	R28, R29
2	Carbon comp (or film) resistor 1/4W 5%	47K	R2, R27
1	Linear Potentiometer	100K	R9
2	Capacitor Aluminum Non polarized	1uF	C8, C9
1	Capacitor Ceramic	.01uF	C5
6	Capacitor Ceramic	.1uF	C1, C2, C3, C4, C12, C13
2	Capacitor Ceramic	330pF	C10, C11
2	Capacitor Electrolytic	220uF	C6, C7
1	DPDT Push On Push Off Foot Switch	DPDT	S1
1	Jack 1/4" 2 Terminal	1/4" Mono Jack	J2
1	Jack Stereo Headphone (TRS)	1/4" Stereo Jack (TRS)	J1
1	9V Battery Clip	9V Battery	B1
1	8 Pin Gold Contact Machined IC Sockets		You'll be glad you used sockets
1	14 Pin Gold Contact Machined IC Sockets		You'll be glad you used sockets
1	16 Pin Gold Contact Machined IC Sockets		You'll be glad you used sockets
4	6-32 3/4" machine screws		For mounting PCB.
4	6-32 nuts		For mounting PCB.
4	3/8" nylon stand-offs		For mounting PCB.
8	#6 x 1/2" pan head phillips screws		For attaching top and back plates.
2	#4 x 1/2" flat head phillips screws		For attaching battery holder.
1	4.5" x 8.75" .08" thick aluminum plate.		For use as faceplate.
1	Knob for 1/4" shaft		Wah Range knob.
6	feet of stranded 24 gauge wire.		For wiring the effect.
4	Self Adhesive Bumper/Feet		Feet for the pedal.
1	Battery Holder		For holding the battery.

Miscellaneous Items You Will Need To Provide

• Wood, to make a footpedal case. Unit is typically mounted in a foot pedal case.
• Digital Volt Meter and a Signal Tracer or oscilloscope for testing.

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