Enclosure not stated · 5 knobs

Mad Professor Sky Blue Overdrive (with mods)

Based on the Mad Professor Sky Blue Overdrive· 5 other boards clone it

Category: Overdrive
Controls: Volume · Distortion · Texture · Z · Tone
Price: see vendor
Also as: Vero layout · from Revolution Deux
Tags: freestompboxes.org trace

Read the post at Revolution Deux Schematic image freestompboxes.org thread Vero layout

From the vendor

Bjorn Juhl's (BJF) four-knob overdrive for Mad Professor, meant to push already distorted amps or give light drive on a clean one. An OP275 gain stage with LED clippers is followed by an unusual 'Texture' network of two 2N3819 JFETs that changes how and when the circuit distorts and its EQ, and a 'Z' pot that sets the load on the guitar pickups.

Mictester's Texture mod (drawn here) works like the original control but needs only a single pot instead of a dual-gang one. The Texture pot can be raised to 5K B for a more useful range (mictester's suggestion).

Schematic

The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.

Parts list 39 rows

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Check before you build · 2 values the reader of this schematic was not sure of

Method's vero (Starr Anise layout) differs from the schematic: C3 220n vs 0.1uF, R12 1.8K vs 620R, Z 500K vs A1M, and it uses the original dual-gang 1K Texture pot.
The Tone control (B2.5K) and the presence parts come from the Vot and Burstcracksplit mods, not the stock four-knob pedal.

Ref	Value	Normalized	Type	Notes
Resistors 17
R11	1K	1k		LED resistor; read from the schematic by eye
R10	47	47		read from the schematic by eye
R4	14.7K	14.7k		read from the schematic by eye
R1	14.7K	14.7k		read from the schematic by eye
R2	2M	2M		read from the schematic by eye
R15	470K	470k		read from the schematic by eye
R14	470K	470k		read from the schematic by eye
R3	3K	3k		read from the schematic by eye
R16	1.2K	1.2k		read from the schematic by eye
R5	47K	47k		read from the schematic by eye
R9	470	470		read from the schematic by eye
R12	620	620		read from the schematic by eye
R17	47K	47k		read from the schematic by eye
R6	47K	47k		read from the schematic by eye
R7	1.3K	1.3k		read from the schematic by eye
R8	470	470		read from the schematic by eye
R13	5.1K	5.1k		read from the schematic by eye
Capacitors 10
C10	100u	100u		electrolytic; read from the schematic by eye
C1	4.7n	4.7n		read from the schematic by eye
C2	100p	100p		read from the schematic by eye
C4	1u	1u		read from the schematic by eye
C3	100n	100n		read from the schematic by eye
C8	1u	1u		electrolytic; read from the schematic by eye
C5	220n	220n		read from the schematic by eye
C6	100n	100n		read from the schematic by eye
C7	47n	47n		read from the schematic by eye
C9	1u	1u		electrolytic; read from the schematic by eye
Diodes 2
D4	5.1V zener	5V1		to LED; read from the schematic by eye
D3	1N4007	1N4007		read from the schematic by eye
Transistors 2
Q1	2N3819	2N3819		read from the schematic by eye
Q2	2N3819	2N3819		read from the schematic by eye
ICs 1
IC1	OP275	OP275		read from the schematic by eye
Potentiometers 5
Z	A1M	A1M	Potentiometer	read from the schematic by eye
Distortion	A1M	A1M	Potentiometer	DIST; read from the schematic by eye
Tone	B2.5K	B2.5k	Potentiometer	tone mod; read from the schematic by eye
Texture	B1K	B1k	Potentiometer	TEXTURE.A; read from the schematic by eye
Volume	B50K	B50k	Potentiometer	VOL; read from the schematic by eye
LEDs 2
D1	Red LED	RED LED		3mm, clipper; read from the schematic by eye
D2	Red LED	RED LED		3mm, clipper; read from the schematic by eye

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