Aion Electronics EQUINOX User manual

EQUINOX AMP OVERDRIVE 1
PROJECT NAME
EQUINOX
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Marshall Guv’nor (Drivemaster)
A great low-to-mid-gain amp-like overdrive with a 3-band EQ.
Amp-Like Overdrive 1.0.2(2021-04-27)
BUILD DIFFICULTY
Easy
Actual size is 2.3” x 1.86” (main board) and 2.3” x 0.86” (bypass board).

EQUINOX AMP OVERDRIVE 2
TABLE OF CONTENTS
1Project Overview 7Drill Template
2Introduction & Usage 8Enclosure Layout
3-4 Parts List 9Wiring Diagram
5Build Notes 10 Licensing
6Schematic 10 Document Revisions
INTRODUCTION
The Equinox Amp Overdrive project is a clone of the Marshall Guv’nor and Drivemaster. (The two pedals
have different names, but they are identical circuits in every way except that the Guv’nor has an effects
loop which has been excluded from this project).
First released in 1988, the Guv’nor was replaced in 1991 by the Drivemaster, the same time the
Shredmaster and Bluesbreaker pedals were released. It was a very popular pedal at the time and
remains well-regarded.
The Guv’nor was among the first overdrive pedals to use a 3-band tone control, allowing for more amp-
like toneshaping via bass, midrange and treble knobs. Interestingly, while it looks like an amp tonestack
on the surface, it’s actually a little closer to a Big Muff tone control in its technology. All three controls
are much more interactive than you’d usually see on an amp.
The Equinox is faithful to the original, but with one added modification: a switch that lets you go
between different clipping diodes. The original has a high clipping threshold using LEDs, but with the
clipping switch you can also select two 1N914s in each direction, as in the Bluesbreaker, or one 1N914
in each direction, as in the Shredmaster.
USAGE
The Equinox has the following controls:
• Treble, Mid and Bass form a passive 3-band tone control for flexible tone shaping.
• Gain controls the amount of gain in the op-amp gain stages that is fed into the clipping stage.
• Volume controls the overall output of the effect.
• Clipping (toggle switch) selects the clipping diodes which changes the character of the drive tone.

EQUINOX AMP OVERDRIVE 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts—most notably potentiometers—so the second
tab lists all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 1M Metal film resistor, 1/4W
R2 2k2 Metal film resistor, 1/4W
R3 10k Metal film resistor, 1/4W
R4 680k Metal film resistor, 1/4W
R5 1k Metal film resistor, 1/4W
R6 1k5 Metal film resistor, 1/4W
R7 680R Metal film resistor, 1/4W
R8 680R Metal film resistor, 1/4W
R9 100R Metal film resistor, 1/4W
R10 22k Metal film resistor, 1/4W
R11 1M Metal film resistor, 1/4W
R12 47k Metal film resistor, 1/4W
R13 47k Metal film resistor, 1/4W
RPD 2M2 Metal film resistor, 1/4W Input pulldown resistor. Can be as low as 1M.
LEDR 4k7 Metal film resistor, 1/4W LED current-limiting resistor. Adjust value to change LED brightness.
C1 10n Film capacitor, 7.2 x 2.5mm
C2 100pF MLCC capacitor, NP0/C0G Some schematics show 120pF here, but the Marshall factory schematic
shows 100pF.
C3 100n Film capacitor, 7.2 x 2.5mm
C4 68n Film capacitor, 7.2 x 2.5mm The original has 220n and 100n capacitors in series, which makes 68n.
C5 220pF MLCC capacitor, NP0/C0G
C6 220n Film capacitor, 7.2 x 2.5mm
C7 100n Film capacitor, 7.2 x 2.5mm
C8 220n Film capacitor, 7.2 x 2.5mm
C9 4n7 Film capacitor, 7.2 x 2.5mm
C10 10n Film capacitor, 7.2 x 2.5mm
C11 68n Film capacitor, 7.2 x 2.5mm
C12 470pF MLCC capacitor, NP0/C0G
C13 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C14 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C15 100n MLCC capacitor, X7R Power supply filter capacitor.

EQUINOX AMP OVERDRIVE 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
D1 1N5817 Schottky diode, DO-41
D2 3mm LED, 3mm, red diffused
D3 3mm LED, 3mm, red diffused
D4 1N914 Fast-switching diode, DO-35
D5 1N914 Fast-switching diode, DO-35
D6 1N914 Fast-switching diode, DO-35
D7 1N914 Fast-switching diode, DO-35
D8 1N914 Fast-switching diode, DO-35
D9 1N914 Fast-switching diode, DO-35
IC1 TL072 Operational amplifier, DIP8
IC1-S DIP-8 socket IC socket, DIP-8
TREBLE 10kB 16mm right-angle PCB mount pot
BASS 10kA 16mm right-angle PCB mount pot
MID 10kA 16mm right-angle PCB mount pot
GAIN 100kB 16mm right-angle PCB mount pot
VOL 100kB 16mm right-angle PCB mount pot
CLIP SPDT cntr off Toggle switch, SPDT on-off-on
LED 5mm LED, 5mm, red diffused
IN 1/4" stereo 1/4" phone jack, closed frame Switchcraft 112BX or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
BATT Battery snap 9V battery snap Optional. Use the soft plastic type—the hard-shell type will not fit.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

EQUINOX AMP OVERDRIVE 5
BUILD NOTES
Clipping switch
The clipping switch allows you select between different sets of diodes.
The center position of the toggle switch is the stock Guv’nor clipping arrangement, which has one LED in
each direction. The upward position of the toggle is two diodes in each direction, a slightly lower clipping
threshold, while the downward position is one diode in each direction like in the Shredmaster.
If you look at the schematic, you’ll see that the LEDs, D2 and D3, are always connected. However, in
either the up or down switch positions, the lower-threshold diodes are connected and so the LEDs have
no effect—there’s no signal remaining for them to clip.
The only thing to be aware of is that since the Guv’nor does not have a gain recovery stage after the
clipping diodes & passive tone stack like the Shredmaster, the diodes will directly affect the maximum
volume of the unit. Using the diodes with the lowest threshold (one 1N914 in each direction), you’ll find
that you have to crank the volume knob pretty high to get unity.

SCHEMATIC
EQUINOX AMP OVERDRIVE 6
GND
2M2
1N5817
100uF
GND
+9V
100n
VA
2k2
10k
680k
1k
1k5680R
680R
100R
22k
1M
47k
47k
10n
TL072P
100pF
100n
GND
100kB
TL072P
68n
220pF
220n
100n
220n
4n7 10n
10kA
10kA
10kB
GND
100kB
GND
GND GND
10uF
GND GND
1M
470pF
GND GND
68n
GND
VB
VB
VB
VA
GND
GND
GND
RPD
D1
C13
IN
OUT
C15
R2
R3
R4
R5
R6R7
R8
R9
R10
R1
R12
R13
C1
IC1A
2
3
1
C2
C3
GAIN
1
2
3
IC1B
6
5
7
84
C4
C5
C6
C7
C8
C9 C10
BASS
1
2
3
MID
1
2
3
TREBLE
1
2
3
VOLUME
1
2
3
C14
R11
C12
C11
D4 D5
D7 D6
CLIP
2
3 1
D9D8
D2
D3
GND

EQUINOX AMP OVERDRIVE 7
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout requires the use of closed-frame jacks like the Switchcraft 111X. Open-frame jacks will
not fit in layouts with 5 or more knobs due to the placement of the DC jack.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
0 1 2
CM
0 1
INCH
x: -0.775, y: +1.71 x: +0.775, y: +1.71
ø9/32” ø9/32”
x: -0.775, y: +0.41
ø9/32”
x: 0, y: +1.71
ø9/32”
x: 0, y: +0.41
ø1/4”
x: +0.775, y: +0.41
ø9/32”
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
CENTER (0,0)
125B
BASSMIDTREBLE
GAINCLIPVOLUME
FOOTSWITCHLED
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN

EQUINOX AMP OVERDRIVE 8
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

EQUINOX AMP OVERDRIVE 9
WIRING DIAGRAM
125B
IN +VGND N.C. N.C. OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT
Shown with optional 9V battery. If battery is omitted, both jacks can be mono rather than one being stereo.
Leave the far-right lug of the DC jack unconnected.

EQUINOX AMP OVERDRIVE 10
LICENSE & USAGE
No direct support is offered for these projects beyond the provided documentation. It’s assumed
that you have at least some experience building pedals before starting one of these. Replacements and
refunds cannot be offered unless it can be shown that the circuit or documentation are in error.
All of these circuits have been tested in good faith in their base configurations. However, not all the
modifications or variations have necessarily been tested. These are offered only as suggestions based
on the experience and opinions of others.
Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
“goop” the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but
please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!)
DOCUMENT REVISIONS
1.0.2 (2021-04-27)
Changed Treble pot to 10kB (previously 10kA) based on review of an original Drivemaster.
1.0.1 (2019-07-28)
Corrected minor errors in PDF parts list. The spreadsheet & schematic were correct.
1.0.0 (2018-12-15)
Initial release.