©2017 by Matthias Herrmann │ Do not copy or distribute by any means │ For private use only │ www.FONITRONIK.de

21.10.2017Thomas Henry Quadrature Function Generator (Eurorack DIY)

IntroductionI consider the Quadrature Function Generator (or QFG) to be one of the classic Thomas Henry deisgns. There has been a PCB years ago, but we thought it would be time to re-publish it again.You can find a detailed description of this design at Scott Stites birthofasynth.com page, where he hosts a lot of information for Thomas Henry designs.

FeaturesTriangle core VCO with four outputs at 0, 90, 180 and 270°,Indicator LEDs,CV input with attenuator,CV input for 1V/OctaveCoarse and Fine tuning pots,Range switch (sub audio/audio range)

SpecificationsThe frontpanel measures: 8HP (Eurorack)Mounting depth behind frontpanel incl. power plug: 40mmPower consumption: TBA

BTW this is not meant as a beginners project. I do not provide step-by-step building instructions. I just assume that you already build quite a few projects and know how to read the BOM and schematics.

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©2017 y Matthias Herr a │ Do ot opy or distri ute y a y ea s │ For private use o ly │ www.FONITRONIK.de

25.09.2017

Layout/Design

Note…… the PCB is cramped with parts, so there are only two mounting holes on the main

PCB. They cannot be used to screw the

main PCB to the adapter PCB.

I recoomend to use precision SIL headers

and receptables, which mate rather firmly.

General mounting instructionsThis project uses two PCBs, one board with

the actual circuitry and an additional adapter

PCB carrying the front panel components.

The adapter PCB is used to mount the PCBs

to the front panel.

The PCBs are connected using two 1x20

headers/receptables with 2,54mm pitch

(.1in). Look out for something like this:

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©2017 y Matthias Herr a │ Do ot opy or distri ute y a y ea s │ For private use o ly │ www.FONITRONIK.de

25.09.2017

Overlay for Reference & Manual Wiring Guide

M1 M3

M2M4

J1: 1

V/O

CT

----

J2: C

V (-A

tt R4

1)----

R4

2: C

OA

RS

E----

R4

3: F

INE

----

-V----

-V----

GN

D----

GN

D----

GN

D----

SW

1: S

PE

ED

)----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

GN

D----

----J6

: OU

TP

UT

90

°

----D

6: LE

D 9

0°

----D

5: LE

D 2

70

°

----J5

: OU

TP

UT

27

0°

----J4

: OU

TP

UT

18

0°

----D

4: LE

D 1

80

°

----J3

: OU

TP

UT

0°

----D

3: LE

D 0

°

----+

V

----+

V

----+

V

----+

V

----+

V

----+

V

----+

V

----G

ND

----G

ND

----G

ND

----G

ND

----G

ND

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©2017 y Matthias Herr a │ Do ot opy or distri ute y a y ea s │ For private use o ly │ www.FONITRONIK.de

25.09.2017

BOM

Qty Value Parts

Resistors

2 10R or ferrite F1, F2

1 100R (trimmer) R1

1 390R R2

8 1k R3, R4, R5, R6, R7, R8, R9, R10

1 2k R11

1 4k7 R12

1 5k6 R13

11 10k R14, R15, R16, R17, R18, R19, R20,

R21, R22, R23, R24

1 12k R25

1 15k R26

1 18k R27

2 22k R28, R29

2 47k R30, R31

1 56k R32

6 100k R33, R34, R35, R36, R37, R38

2 100k (trimmer) R39, R40

1 150k R44

1 3M3 R45

Capacitors

2 100pF C1, C2

1 1n C3

1 2n2 C4

1 4n7 C12A (timing cap)

7 10n DC1, DC2, DC3, DC4, DC5, DC6, DC11

2 100n C13A, C14A

1 470n C12B (timing cap)

2 10uF C13, C14

Qty Value Parts

Semi's

2 1N4148 D1, D2

2 1N4004 PD1, PD2

1 2N3904 Q1

2 2N3906 Q2, Q3

1 J112 Q4

1 LM13700 IC1

4 TL072 IC2, IC3, IC5, IC6

1 CD4001 IC4

Misc (Adapter PCB)

1 SPDT on-on

(miniature)

SW1

3 100k (9mm

Potentiometer)

R41, R42, R43

1 Socket (PJ-301B) J1 - J6

4 LED (3mm) D3, D4, D5, D6

2x 20pol SIL header (female)

2x 20pol SIL header (male)

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COARSE

FINE

ATTEN

SLOW

FAST

100n

100n

-12V

+12V10R or ferrite

10R or ferrite

1N4004

1N4004

TL072B

TL072B

TL072BTL072B

10n

10n

10n

10nGND

LM13700

LM13700

10n

10n

CD4001

10n

100k

47k

100k

3M3

2k

390R

100pF

100R

2N3904

+12V

2N3906

100k

-12V

18k

470n4n7

10k

-12V

56k

+12V

5k610k

-12V

1N4148

47k 2N3906

4k7

-12V

10k

1N4148

10k

12k

15k

1k

1k

10k

10k 1k

1k

TL072B

TL072B

TL072BTL072B

100k

100k

J112

10k

10k

10k 100k

100k 100k

100pF

150k

+12V

22k 22k

2n2

1n

1k

1k

10k

10k

1k

1k

+12V

-12V

+12V

1V/OCT

ENVELOPE

+12V

+12V

-12V

-12V

0° OUTPUT

180° OUTPUT

LED

LED

270° OUTPUT

90° OUTPUT

LED

LED

SPDT

IC2IC3 IC1

V/oct

IC5IC6

Connect Trim

Offset Trim

EURO-1

EURO-2EURO-3

EURO-4EURO-5

EURO-6EURO-7

EURO-8

EURO-9EURO-10

C13A

C14A

F1

F2

PD1

PD2

2

31IC2A

6

57

IC2B

2

3

1IC3A 6

5

7IC3B

84

84

DC3

DC4

DC5

DC6

4

3

1

5IC1A 13

14

16

12IC1B

7 8

10 9

11

6

DC1

DC2

1

23

IC4A

5

6

4

IC4B

8

910

IC4C 12

1311

IC4D

IC4P

VD

DVSS

714

DC11

R33

R30

R34

R45

R11

R2

C1

AE

S

R1

Q1

Q2

R35

R27

C12BC12A

R14

R32

R13R15

D1

R31

Q3

R12

R19

D2

R18

R25

R26

R4

R3

R16

R17 R5

R6

2

31IC5A

6

5

7IC5B

2

31IC6A

6

5

7IC6B

84

84

AE

S

R40

AE

S

R39

D

SG

Q4

R20

R21

R22 R38

R36 R37

C2

R44

R28 R29

C4

C3

R7

R8

R24

R23

R9

R10

M1-1

M1-2

M1-3

M1-4

M1-5

M1-6

M1-7

M1-8M1-9

M1-10

M2-1

M2-2

M2-3

M2-4

M2-5

M2-6

M2-7

M2-8

M2-9M2-10

1MTA-156

M3-1M3-2

M3-3M3-4

M3-5M3-6

M3-7M3-8

M3-9

M3-10

M4-1M4-2

M4-3M4-4

M4-5M4-6

M4-7M4-8

M4-9

M4-10

J1

J2

R41100k

R42100k

R43100k

J3

J4

D3

D4

J5

J6

D5

D6

SW1

A

A

THOMAS HENRY QFGQuadrature Function Generator 2007

Redrawn schematic by Matthias Herrmann 2017

1.0

++

GND

+15V

-15V

Page 5 of 5