Mod THE RING IN RETURN User manual

1Copyright © 2021 by modelectronics.com
Use these instructions to learn:
How to build an effects pedal for octave fuzz.
The Ring In Return is an octave-up fuzz effect that is an all-analog design that captures those late 60s
octave-up fuzz tones. Transformer-coupled germanium diodes produce sounds that range from a subtle
octave-up to thick, harmonically-rich sonic textures, and synth-like tones. Experimenting with different
pickups and tone-control settings on your guitar with The Ring In Return can also produce sitar-like sounds.
THE RING IN RETURN (K-903)
Warning: This circuit was designed for use with a 9 VDC power supply only.
TO
AMP
IN
FROM
GUITAR
OUT
Unplug when not in use
to save battery life.
9 VDC
CENTER (-)
ADAPTER

TABLE OF CONTENTS
TOOL LIST ……………………………………………………………………………………….2
PARTS LIST DRAWINGS……………………………………………………………………...3, 4
FINAL ASSEMBLY REFERENCE DRAWING…………………………………………………..5
SOLDERING TIPS ……………………………………………………………………………….6
STEP BY STEP ASSEMBLY INSTRUCTIONS …………………………………………..7 - 10
Section 1 – Mount Large Components ………………………………………………….7
Section 2 – Wire Large Components ……………………………………………………….7
Section 3 – Mount Components to Terminal Strips ………..……………………………..8
Section 4 – Finishing Up ......……………………………………………………………10
ASSEMBLY DRAWINGS (4 Drawings) ……………………………………………..11, 12
These should be separated and used as a reference to help assemble the kit correctly.
STICKER APPLICATION…..…………………………………………………………………….13
2
TOOL LIST
Wire Strippers
Needle Nose Pliers
Cutting Pliers
Desoldering Pump
Solder (60/40 rosin core)
Soldering Station
Phillips Head Screwdrivers
Slotted tip screwdrivers (3 mm tip)
Channellock Pliers (or similar type)
Ruler
Hobby Vise (or other means to secure box while working)
Xacto Knife or similar cutting tool

Enclosure
P-H1590BBCE-BK (1)
MXR Style Knob
P-K345-GLOW (2)
Battery Clip
S-H155 (1)
¼” Mono Jack (Output Jack)
W-SC-11-T (1)
¼” Stereo Jack (Input Jack)
W-SC-12B (1)
Stranded Wire (22 AWG) - Red
K-PUL1569 (4 FT)
PARTS LIST 1
3
RING LUG
SLEEVE LUG
TIP LUG
GROUND LUG
TIP LUG
Potentiometers: 1KL and 500KA
R-VA1KL (1)
1
2
3
R-VA500KA (1)
#4 Screw (3/8" long)
S-HS440-38 (7)
#4 Nut
S-HHN440 (7)
#4 Lock Washer
S-HLW4 (7)
Terminal Strip with 8 Terminals
P-0802H (2)
DC Power Jack
S-H750 (1)
Terminal Strip with 3 Terminals
P-0301H (1)
Terminal Strip with 5 Terminals
P-0501H (2)
Light Emitting Diode
P-L400 (1)
+
-
3PDT Foot Switch
P-H501-L-BLK (1)
Black Dress Nut
P-H54-DRESS-BLK (1)

PARTS LIST 2
4
0.001µF Capacitor 100V
C-PEID001-100 (1)
Audio Transformer (1.5K : 600 Ω)
P-T42TM022 (1)
P-Q2N5088 (2)
NPN BJT (2N5088)
2N
5088
E B C
K-PQ-2N3906 (1)
PNP BJT (2N3906)
2N
3906
EBC
C-ET100-25-IL (2)
100µF Polarized Capacitor 25V
100µF 25V
P-Q972 (2)
Germanium Diode (1N34A)
33µF 50V
C-ET33-50 (2)
33µF Polarized Capacitor 50V
150
500V
150pFCapacitor 500V
C-SM150 (1)
0.1µF Capacitor 100V
C-PEID1-100 (1)
104J
102J
red
red
brown
gold
220
220Ω Resistor ½ W
R-A220 (1)
yellow
violet
brown
gold
470
470Ω Resistor ½ W
R-A470 (1)
brown
black
red
gold
1K
1kΩ Resistor ½ W
R-A1K (1)
brown
red
red
gold
1.2K
1.2kΩ Resistor ½ W
R-A1D2K (1)
red
red
orange
gold
22K
22kΩ Resistor ½ W
R-A22K (1)
yellow
violet
orange
gold
47K
47kΩ Resistor ½ W
R-A47K (1)
red
black
yellow
gold
200K
200kΩ Resistor ½ W
R-A200K (1)
red
red
yellow
gold
220K
220kΩ Resistor ½ W
R-A220K (1)
blue
gray
yellow
gold
680K
680kΩ Resistor ½ W
R-A680K (1)
gray
red
yellow
gold
820K
820kΩ Resistor ½ W
R-A820K (1)
brown
black
green
gold
1M
1MΩ Resistor ½ W
R-A1M (1)
SPDT Toggle Switch
P-H540 (1)
Toggle Switch Cap - Black
P-HTCAP-B (1)
gray
red
brown
gold
820
820Ω Resistor ½ W
R-A820 (1)
Sticker
K-903-LABEL (1)

FINAL ASSEMBLY REFERENCE DRAWING
This is a large version of the final assembly drawing. Refer to this drawing as you make your way through each step of the instructions. Before you make a new
connection at a particular terminal or solder lug, notice how many other connections will be made at that terminal. That way you can decide whether it’s best for
you to solder the connection and leave space open for future connections or hold off on soldering until after every connection at that location has been made.
5
1
2
31
2
3
1KL 500KA
1 8
9
15
16
19 20
23
25
NC
NC
NC
NC
680K .1µ
1M
820K
33µF 50V
200K 220K
150p
220
2N
3906
E B C
Q1
.001µ
22K
EBC
2N5088
Q2
1.2K
47K
100µF 25V
E
B
C
100µF 25V
470
Q3
“P”
33µF 50V
red
black
22
1
2
3
4
5
6
7
8
9
-
+
1K
820
47K47K

SOLDERING TIPS
1. Bend the component lead
and wrap it around the
connection point.
2. Wrap the component lead
so that it can hold itself to the
connection point.
3. Heat up both component
lead and connection point with
the soldering iron.
4. Apply solder to both
component lead and
connection point.
2. Apply fresh solder to mix in
with old solder joint
1. Heat up old solder joint
with the soldering iron.
3. Use a de-soldering tool to
remove the old solder joint
while it is heated.
De-Soldering Tip
6
It is important to make a good solder joint at each connection point. A cold solder joint is a connection that
may look connected but is actually disconnected or intermittently connected. (A cold solder joint can keep
your project from working.)
Follow these tips to make a good solder joint. Take your time with each connection and make sure that all
components are connected and will remain connected if your project is bumped or shaken.
Bend the component lead or wire ending and wrap it around the connection point.
Make sure it is not too close to a neighboring component which could cause an
unintended connection.
2. Wrap the component lead so that it can hold itself to the connection point.
Touch the soldering iron to both the component lead and the connection point allowing both to
warm up just before applying the solder to them.
Be sure to adequately cover both component lead and connection point with melted solder.
Remove the soldering iron from your work and allow the solder joint to cool. (The
solder joint should be shiny and smooth after solidifying.)
Cut off any excess wire or component leads with cutting pliers.
Clean the soldering iron's tip by wiping it across the wet sponge again after making the
solder joint.

SECTION 1 – Mount Large Components
Stripping wire, tinning wire and soldering. Throughout these instructions you will be told to strip
and tin a length of wire numerous times. Unless noted otherwise, cut the wire to the length stated in
the instructions. Then strip ¼” of insulation off each end. Twist each end of the stranded wire, and
apply a small amount of solder to each end (i.e. tin the wire ends).
Please refer to DRAWING 1 and DRAWING 2.
Orient the enclosure with the two 5/16" holes on top.
Using the seven screws, nuts and lock washers provided,
fasten the five terminal strips to match DRAWING 2.
12
3
4 5 6 7
The ends may require trimming or filing for a perfect fit. Fasten the two 5 lug
terminal strips and the 3 lug terminal strips first. Then fasten the two 8 lug terminal strips.
Alignment
Tab
Mount the DC power jack in the 15/32" hole on the left side of
the enclosure. Orient its solder lugs so that the center-pin lug
is facing the bottom side of the enclosure. CENTER-PIN
LUG
POSITIVE-SWITCH
LUG
POSITIVE
LUG
Mount the input jack in the 3/8" hole on the left side of the enclosure with the hardware provided.
The washer goes under the nut on the outside of the enclosure. Make sure the center solder lug of
the input jack is facing up. Correct positioning of the jack makes soldering the connections easier.
Mount the output jack in the 3/8" hole on the right side of the enclosure. Make sure the two solder
lugs are in their most upright position before tightening the nut.
Mount the footswitch in the 15/32" hole in the center of the enclosure. The black washer goes under
the mounting nut on the outside of the enclosure. Then the lock washer mounts on the inside
between the enclosure surface and the other nut. Discard the nylon washer. Make sure that the
footswitch is oriented to match DRAWING 2.
SECTION 2 – Wire Large Components
Please refer to DRAWING 3.
Please note that each terminal has been numbered as
illustrated here and will be referred to as a “terminal #_” when
connecting different components and wires throughout the
assembly instructions.
7
12345678
9101112131415
16
17
18
19 20
21
22
NC
NC
NC
NC
232425
This will prevent the stranded wire from fraying and will make the
final soldering much easier.
Apply the sticker to the top of the box then use a blade to cut out the holes. See pg 13 for guide.
Mount the SPDT toggle switch in the ¼” hole at the top. Leave all stock hardware on the bushing
and make sure they are fully threaded before inserting through the chassis hole. Use the black
dress nut to mount the switch. Align the switch as shown in the drawing and tighten the nut.
Mount the LED in the ¼” hole above the footswitch’s mounting hole. The lock washer goes under
the nut inside the enclosure. Align the LED leads so that the cathode (short lead) is closer to the
footswitch as shown in Drawing 2.
anode
Mount the 1KL pot in the 5/16" hole on the left and the 500KA pot in the remaining 5/16" hole
on the right. Bend back and remove the alignment tab on the top of each potentiometer
using a pair of pliers before mounting the pots so that they can mount flush
against the enclosure surface.
end end
cathode

Strip and tin a 2" piece of wire and connect Footswitch lug 8 to the output jack’s tip lug.
Strip and tin a 1 ½” piece of wire and connect Footswitch lugs 3 and 9.
Strip and tin a 2” piece of wire and connect Footswitch lug 2 to the input jack’s tip lug.
Strip and tin a 4" piece of wire and connect Footswitch lug 7 to the 500KA pot’s lug 2.
Strip and tin a 1 ½” piece of wire and connect it from the lower hole of
terminal #7 to the lower hole of terminal #12. (This allows for more
room when connecting components later in the instructions). lower holes
8
Strip and tin a 2 ½” piece of wire and connect it from the lower hole of terminal #2 to the lower
hole of terminal #6.
Strip and tin a 1 ¼” piece of wire and connect it from terminal #4 to the lower hole of terminal
#13. Do not solder either connection yet.
Strip and tin a 2" piece of wire and connect it from terminal #4 to the
power jack’s positive lug. Leave room at #4 for the 200K resistor that
will mount to #3 and #4 later on.
CENTER-PIN LUG
POSITIVE LUG
Strip ¾” of insulation off the end of the wire spool, twist and tin it. When this tinned wire end
cools, cut off the bare portion of wire. (This will be used as a short jumper wire). Connect this
jumper from the power jack’s center-pin lug to terminal #1. Use the excess length of this jumper
to wrap around the connection points.
Strip and tin a 1 ¼” piece of wire and connect the 500KA pot’s lug 3 to terminal #9.
Strip and tin a 4" piece of wire and connect from the lower hole of terminal #14 to the lower hole
of terminal #20.
Strip and tin a 1 ¾” piece of wire and connect terminals #11 and #16.
Strip and tin a 1 ½” piece of wire and connect terminal #18 to the 1KL pot’s lug 1. Do not solder
the terminal #18 connection yet.
Strip and tin a 1 ½” piece of wire and connect terminals #18 and #19. Now solder the #18
connection.
Double check all of your connections at this point because it will be very difficult to make
corrections after the components are soldered into place.
SECTION 3 – Mount Components to Terminal Strips
Please refer to DRAWING 4.
Connect and solder all the following components to their respective terminals as listed. (Make sure
that none of the component leads are so close together that it could cause an unintended short).
Connect the 680K resistor to terminals #1 and #2.
Connect the 0.1µF cap to terminal #2 and Footswitch lug 1. Mount this cap upside down with its
leads facing up.
Connect the 1M resistor to footswitch lug 1 and the input jack’s ground lug.
Strip and tin a 2” piece of wire and connect terminal #25 and lug 2 of the SPDT toggle switch.
Do not solder the terminal #25 connection yet.
Strip and tin a 2” piece of wire and connect terminal #22 and lug 1 of the SPDT toggle switch.
Do not solder the terminal #22 connection yet.
Strip and tin a 2" piece of wire and connect Footswitch lug 5 to the output jack’s sleeve lug.
Strip and tin a 1 ¼” piece of wire and connect terminal #13's lower hole and the long lead
(anode) of the LED. Solder both connections now.

9
Connect the 820K resistor to terminals #2 and #3. Push this component down slightly to allow
room for the next component. Do not solder the connection on terminal #3 yet.
Connect one of the 33µF caps to terminals #1 and #3. Make sure the
negative (-) end of the cap is connected to terminal #1. Do not solder
the connection on terminal #3 yet.
33µF 50V
negative end
Connect the 200K resistor to terminals #3 and #4. Solder the connections at #3 now.
Connect the 220K resistor to terminals #7 and #8.
Connect the 150pF cap to terminals #6 and #8. Push this cap down to allow room for the next
component.
Connect the 220 ohm resistor to terminals #7 and #10.
Connect the 1K resistor to terminal #5 and #15. Now solder the #5 connection.
Connect the .001µF cap to terminals #9 and #10.
Connect the 22K resistor to terminals #9 and #11.
Connect the 1.2K resistor to terminals #13 and #14. Leave room on #14 for mounting Q3 later.
Connect the 47K resistor to terminals #14 and #15. Leave room on #14 for mounting Q3 later.
Connect the positive (+) end of a 100µF cap to terminal #15 and
the negative (-) end to both lugs 2 and 3 of the 1KL pot. 100µF 25V
negative end positive end
Connect the 470 ohm resistor to terminals #17 and #19. (Remember that terminals #17 and #19
are three terminals apart from one another so make sure you connect correctly).
Connect one of the 2N5088 transistors to terminals #11, #12 and #13 as listed below.
Terminals #11: Emitter
Terminals #12: Base
Terminals #13: Collector
2N
5088
E B C
Connect the remaining 2N5088 transistor to terminals #14, #16 and #17 as listed below.
Terminals #14: Collector
Terminals #16: Base
Terminals #17: Emitter
2N
5088
E B C
Connect the 2N3906 transistor to terminals #5, #6 and #7 as listed below. Do not solder the
terminal #5 connection yet.
Terminals #5: Emitter
Terminals #6: Base
Terminals #7: Collector
2N
3906
EBC

10
Connect the remaining 100µF cap to terminals #17 and #19.
Make sure the negative (-) end is connected to #19.
100µF 25V
negative end
Press the metal mounting tabs of the transformer inward so they are
flush with the bottom of the transformer. Now place the transformer
upside down in the enclosure in the area shown on DRAWING 4.
The side marked “P” should be facing the top side of the enclosure.
With the transformer resting upside down, insert its three leads facing the bottom side of the
enclosure through terminals #23, #24 and #25, but do not solder.
Only two of the three leads on the “P” side of the transformer will be used. Connect the lead on
the left side to terminal #18. Connect the lead on the right side to terminal #21.
Carefully clip off the remaining unused middle lead on the “P” side of the transformer and solder
the three transformer lead connections at terminals #23, #24 and #25.
Connect the remaining 33µF cap to terminals #20 and #21. Make sure the negative (-) end is
connected to #21.
Connect one of the 1N34A diodes to terminal #23 and the
500KA pot’s lug 1. Make sure the banded end (cathode)
connects to the pot lug 1. Do not solder the Pot lug 1
connection yet.
cathode endanode end
Connect the remaining 1N34A diode to terminal #22 and lug 1 of the 500KA pot (also with the
banded end (cathode) at lug 1). Now solder the connection at lug 1.
SECTION 4 – Finishing Up
Attach the knobs provided to the two potentiometer shafts. Install 9 volt battery, close cover using
screws provided. Plug guitar into input jack on right. This turns unit on. Plug cable into output jack
and plug into your amplifier.
Unplug from the input jack of the unit to turn it off and save power.
It’s always a good idea to thoroughly double-check your connections before applying power.
Locate the battery snap connector. Connect and solder the red lead
to the positive-switch lug of the power jack.
RING LUG
SLEEVE LUG
TIP LUG
Input Jack
Connect and solder the black lead of the battery snap
connector to the input jack’s ring lug.
POSITIVE-SWITCH LUG
mounting tabs
Connect and solder the 820 ohm resistor from lug #4 of the
footswitch to the negative lead of of the LED. Be careful not
to touch the resistor or LED leads to any other part.
Clip the anode lead of the LED and resistor to a reasonable
length and connect them by bending and crimping the leads
around each other. Solder them once they are tightly
connected to each other.
band

1
2
31
2
3
DRAWING 1
TOP
LEFT SIDE
RIGHT SIDE
INSIDE VIEW OF THE
ENCLOSURE
DRAWING 2
15/32"
1/8"
1/8" 1/8"
1/8"
1/8"1/8"
3/8"3/8"
15/32"
5/16"
5/16"
1/8"
1KL 500KA
11
1
2
3
1
2
3
4
5
6
7
8
9
-
+
1/4"
1/4"

DRAWING 3
DRAWING 4
1
2
31
2
3
1KL 500KA
18
9
15
16
19 20
2325
NC
NC
NC
NC
1
231
2
3
1KL 500KA
1 8
9
15
16
19 20
2325
NC
NC
NC
NC
680K .1µ
1M
820K
33µF 50V
200K 220K
150p
220
2N
3906
E B C
Q1
1K
.001µ
22K
EBC
2N
5088
1.2K
47K
100µF 25V
E
B
C
100µF 25V
470
Q3
“P”
33µF 50V
red
black
12
1
2
3
4
5
6
7
8
9
-
+
1
2
3
4
5
6
7
8
9
820
Q2
-
+
22
22

APPLYING THE STICKER TO MOD PEDAL ENCLOSURES
Locate the top of the pedal as well as
the top of the sticker. Page one of the
instructions for your kit will have an
image of the pedal that can be used for
reference.
Peel the backing from the sticker. Carefully line
up the top edge of the sticker with the top of the
pedal. Press down to apply the sticker only to the
edge. Run a finger across the edge to push any air
out from beneath the sticker. Continue this motion
as you work your way down the pedal until the
sticker is fully attached.
Locate the holes beneath the sticker and
depress them using a fingertip. Be sure
that the area of the sticker surrounding the
holes is fully adhered to the surface.
With an Xacto knife or similar tool,
carefully pierce the sticker in the center of
each hole. Carefully work the knife from
the center of the hole to the edge and
begin cutting fully around the edge until
the sticker has been fully cleared from the
hole.
1. 2.
3. 4.

Copyright © 2021 by modkitsdiy.com
“The Ring In Return” (K-903)
Schematic
3PDT Foot Switch
Base
Emitter
Collector
MPSA18
NPN BJT
B C
E
Base
Emitter
Collector
2N3906
PNP BJT
BCE
+
-
9 VDC
Battery
Output
Input
Foot
Switch
(A)
Foot
Switch
(B)
2
1
2
7
8
9
2N3906
Q1 C
B
E
.1µ
1M
500KA
33µ
OUTPUT
200K
820K
680K 150p
220K
100µ
1KL 1K
47K
MPSA18
C
B
E
220
.001µ
MPSA18
C
B
E
22K 470 100µ
1.2K
33µ 1N34A
1N34A
P-T42TM022
+
+
+
+
BOOST
Q2 Q3
DC Power
Jack
center (-)
“P”
1.5KΩ
600 Ω
P-T42TM022
DCR Measurements
“P”
61.9 Ω 46.5 Ω
4.20
VDC
4.22 VDC
3.5 VDC
2.9
VDC
9.1 VDC
2.3
VDC
1.7 VDC
4.8
VDC
7.9
VDC
3.7 mA(DC)
4
+-
820Ω
6
5
1
2
3
4
5
6
7
8
9
LED
1
3
2

1
231
2
3
1KL 500KA
1 8
9
15
16
19 20
2325
NC
NC
NC
NC
680K .1µ
1M
820K
33µF 50V
200K 220K
150p
220
2N
3906
E B C
Q1
1K
.001µ
22K
EBC
2N
5088
1.2K
47K
100µF 25V
E
B
C
100µF 25V
470
Q3
“P”
33µF 50V
red
black
12
1
2
3
4
5
6
7
8
9
820
Q2
-
+
22
Use this troubleshooting supplement to help:
Measure DC voltage test points to identify major discrepancies and locate problem areas.
(Keep in mind that the voltage measurements will vary slightly from kit to kit. The voltages you measure should be in
the same ballpark, but do not expect to get the exact same value.)
Using a volt meter, connect the ground side lead of the meter to any ground point on the pedal.
One ground point would be the output jack’s ground lug. The other volt meter lead will be used to
measure DC voltage at the test points shown below.
A
B
C
DE F
G
HI
J
K
L
Don’t forget to plug into the input
jack if you are testing with a battery
as the power supply.
A (Power Supply):
B (33µF cap):
D (Q1 Base):
E (Q1 Emitter):
F (Q1 Collector):
G (Q2 Base):
H (Q2 Collector):
I (Q2 Emmiter):
C (100µF cap):
J (Q3 Base):
K (Q3 Collector):
L (Q3 Emitter):
DC Voltage Test Points
9.1 VDC
7.9 VDC
4.22 VDC
3.5 VDC
4.20 VDC
2.9 VDC
2.9 VDC
9.1 VDC
2.3 VDC
2.3 VDC
4.8 VDC
1.7 VDC

1
231
2
3
1KL 500KA
1 8
9
15
16
19 20
2325
NC
NC
NC
NC
680K .1µ
1M
820K
33µF 50V
200K 220K
150p
220
2N
3906
E B C
Q1
1K
.001µ
22K
EBC
2N
5088
1.2K
47K
100µF 25V
E
B
C
100µF 25V
470
Q3
“P”
33µF 50V
red
black
12
1
2
3
4
5
6
7
8
9
820
Q2
-
+
22
Measuring AC Voltages from the Guitar Signal
Sleeve Tip
Sleeve
Terminal
(Ground)
Tip
Terminal
(Output)
Tip
Spring
¼” (Mono) Plug
¼” Jack
Once your DC voltages are in order, if your kit is still not working properly, you can
measure AC voltages along the signal path to troubleshoot further.
You will need a volt meter that can measure the small signal AC voltages that electric
guitars put out. The output signal from your guitar will likely be less than 1 V.
First, measure the output signal directly from your guitar. You can do this by plugging your
guitar cable into the guitar and leaving the other end of the cable disconnected. Connect your
meter across the disconnected ¼" plug's "tip" and "sleeve" sections. Make sure your guitar's
volume and tone controls are turned up and strum a chord. When you strum, you should see
the AC voltage reading on the meter quickly rise to some maximum value and then fall back to
0 VAC when you stop strumming and the strings are at rest.
Once you are able to measure the output signal from your guitar directly, plug the guitar into the input jack of your kit and use the AC test points to measure the guitar
signal along the signal path. Start with test point one and move along in order. You should be looking to identify the last test point where the signal seems normal and the
first test point where the signal seems unusual or where it is no longer even present.
1 = Input jack tip lug 0.18 VAC
AC Voltage (Signal) Test Points
2 = Input to effect circuit 0.18 VAC
3 = Q1 base 0.18 VAC
4 = Q2 base 1.9 VAC
5 = Q3 base 1.8 VAC
6 = Transformer primary 2.6 VAC
7 = Diode cathodes 0.2 VAC
8 = Output jack tip lug 0.2 VAC
1
2
3
4
5
6
7
8
Control settings for Voltage Measurements
Output (500KA) = full clockwise rotation (max)
Fuzz (1KL) = full counter-clockwise rotation (min)
Octave (Toggle) = On (toggle pointing to Octave text)
Guitar: Strat Neck Pickup (full volume and tone settings)

3PDT Foot Switch
1
2
3
4
5
6
7
8
9
+
-
9 VDC
Battery
Output
Input
Foot
Switch
(A)
Foot
Switch
(B)
2
3
1
7
8
9
2N3906
Q1 C
B
E
.1µ
1M
500KA
33µ
OUTPUT
200K
820K
680K 150p
220K
100µ
1KL 1K
47K
MPSA18
C
B
E
220
.001µ
MPSA18
C
B
E
22K 470 100µ
1.2K
33µ 1N34A
1N34A
P-T42TM022
+
+
+
+
BOOST
Q2 Q3
DC Power
Jack
center (-)
“P”
1.5KΩ
600 Ω
4.20
VDC
4.22 VDC
3.5 VDC
2.9
VDC
9.1 VDC
2.3
VDC
1.7 VDC
4.8
VDC
7.9
VDC
3.7 mA(DC)
4
+-
820Ω
6
5
LED
1
3
2
Copyright © 2021 by modkitsdiy.com
“The Ring In Return” (K-903)
Schematic
Base
Emitter
Collector
MPSA18
NPN BJT
B C
E
Base
Emitter
Collector
2N3906
PNP BJT
BCE
P-T42TM022
DCR Measurements
“P”
61.9 Ω 46.5 Ω
4.20
VDC
4.22 VDC
3.5 VDC
2.9
VDC
9.1 VDC
2.3
VDC
1.7 VDC
4.8
VDC
7.9
VDC
A
B
C
D
E
F
G
H
I
J
K
L
1
2 3 4 5
6
7
8
.18
VAC
.18
VAC
.18
VAC
1.9
VAC
1.8
VAC
2.6
VAC
.2
VAC
.2
VAC
Letters A to L = DC Voltage Measurements
Numbers 1 to 8 = AC Signal Voltage Measurements
Control settings for Voltage Measurements
Output (500KA) = full clockwise rotation (max)
Fuzz (1KL) = full counter-clockwise rotation (min)
Octave (Toggle) = On (toggle pointing to Octave text)
Guitar: Strat Neck Pickup (full volume and tone settings)