aion PLASMA VINTAGE DRIVE User manual

PLASMA VINTAGE DRIVE 1
PROJECT NAME
PLASMA
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Colorsound Overdriver
A reproduction of a boost pedal from the early 1970s that featured a two-band tone stack.
Boost / drive 1.0.1 (2020-07-20)
BUILD DIFFICULTY
Easy
Actual size is 2.3” x 1.86” (main board) and 2.3” x 0.86” (bypass board).

PLASMA VINTAGE DRIVE 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 Plasma Vintage Drive is a clone of the Colorsound Overdriver, a transistor-based boost/drive pedal
with 2-band tonestack that was first sold in 1972.
The Overdriver was an updated version of the Power Booster from 1970. The Power Booster ran at 18V
using two batteries in series. The Overdriver dropped the requirement of the second battery and ran on
a normal 9V supply. There were a few other very minor tweaks to component values, but it’s the same
basic circuit.
The Plasma project is a direct clone of the Overdriver, but with one modification: it adds an output
volume control. This way you can set the gain according to the tone you want without being tied to the
volume that is produced along with it.
Note that the Overdriver can be “splatty” at medium gain levels as the notes decay. It works best at low
gain as a clean boost with tone-shaping capabilities, or at high gain where it’s not unlike a Big Muff. If you
hear this splattiness, know that it’s a byproduct of transistor-based distortion and it’s working correctly!
The 125B version of the Plasma is different from the first version in that it drops the Power Booster
compatibility. The Power Booster is instead available as another circuit, the Nucleus, which has an on-
board charge pump for 18V operation. In addition, in this updated version, the transistor bias trimmers
have been removed. It’s not necessary to bias the transistors in the Overdriver circuit for correct
operation.
USAGE
The Plasma has two controls and one toggle:
• Gain controls the amount of gain from the first transistor stage.
• Treble controls the high-end response of the circuit and forms half of the Baxandall tone stack.
• Bass controls the low-end response of the circuit and forms the other half of the Baxandall tone
stack.
• Volume is the output volume of the effect.

PLASMA VINTAGE DRIVE 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—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 120k Metal film resistor, 1/4W 100k in some units.
R2 150k Metal film resistor, 1/4W
R3 6k8 Metal film resistor, 1/4W
R4 1k8 Metal film resistor, 1/4W
R5 470R Metal film resistor, 1/4W
R6 12k Metal film resistor, 1/4W
R7 4k7 Metal film resistor, 1/4W
R8 4k7 Metal film resistor, 1/4W
R9 39k Metal film resistor, 1/4W
R10 5k6 Metal film resistor, 1/4W
R11 150k Metal film resistor, 1/4W
R12 33k Metal film resistor, 1/4W
R13 1k8 Metal film resistor, 1/4W
R14 470R Metal film resistor, 1/4W
R15 100R 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 220n Film capacitor, 7.2 x 2.5mm
C2 22uF Electrolytic capacitor, 5mm 10uF in some units.
C3 220pF MLCC capacitor, NP0/C0G 470pF in some units.
C4 10uF Electrolytic capacitor, 5mm
C5 22uF Electrolytic capacitor, 5mm
C6 100n Film capacitor, 7.2 x 2.5mm
C7 10n Film capacitor, 7.2 x 2.5mm
C8 10n Film capacitor, 7.2 x 2.5mm
C9 100n Film capacitor, 7.2 x 2.5mm
C10 10uF Electrolytic capacitor, 5mm
C11 100pF MLCC capacitor, NP0/C0G
C12 22uF Electrolytic capacitor, 5mm
C13 220n Film capacitor, 7.2 x 2.5mm

PLASMA VINTAGE DRIVE 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C14 100uF Electrolytic capacitor, 6.3mm
C15 100n MLCC capacitor, X7R
D1 1N5817 Schottky diode, DO-41
Q1 2N5088 BJT transistor, NPN, TO-92 Original units used BC109, BC169C, BC184C or BC184L. These are all
high-gain transistors (hFE 400+). 2N5088 is a suitable low-noise and
commonly-available replacement. See build notes for more info.
Q2 2N5088 BJT transistor, NPN, TO-92
Q3 2N5088 BJT transistor, NPN, TO-92
BASS 100kB 16mm right-angle PCB mount pot
DRIVE 1kC 16mm right-angle PCB mount pot Original uses 10kB, but 1kC will provide a much more usable control.
TREBLE 100kB 16mm right-angle PCB mount pot
VOL. 100kA 16mm right-angle PCB mount pot
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.

PLASMA VINTAGE DRIVE 5
BUILD NOTES
Transistor outlines
The PCB has outlines for either TO-18 (metal can) or TO-92 transistors. The BC109C is TO-22, but the
other recommended types are TO-92. All three pads are connected together for each transistor, so only
use one or the other from each pair.
Be careful of the pinout. The TO-92 outline is set up for USA convention (2N5088, 2N3904, etc.) but
the original transistors used European convention which is reversed. If using any of the BC-series
transistors, you’ll likely need to rotate them 180 degrees, but check the datasheet or measure them with
a transistor tester to be sure.

SCHEMATIC
PLASMA VINTAGE DRIVE 6
GND
2M2
5817
100uF
1kC
100kB
GND
100kB
100kA
+9V
100n
VA
220n
2N5088
120k
VA
150k
6k8
22uF
GND
GND
2N5088
12k
220pF
10uF
1k8
VA
470R
22uF
GND GND
4k7 4k7
100n39k
10n
5k6
10n 100n
2N5088
150k
10uF
33k
GND
VA VA
1k8470R
22uF
GND GND
220n
100pF
GND
100R
IN
OUT
RPD
D1
C14
1
2
3
DRIVE
BASS
1
2
3
1
2
3
TREBLE
VOLUME
1
2
3
C15
C1
Q1
R1
R2
R3
C2
Q2
R6
C3
C4
R4R5
C5
R7 R8
C6R9
C7
R10
C8 C9
Q3
R11
C10
R12
R13R14
C12
C13
C11
R15
GND

PLASMA VINTAGE DRIVE 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 assumes the use of closed-frame jacks like the Switchcraft 111X. If you’d rather use
open-frame jacks, please refer to the Open-Frame Jack Drill Template for the top side.
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: -0.65, y: +1.71 x: 0.65, y: +1.71
ø9/32” ø9/32”
x: -0.65, y: +0.41
ø9/32”
x: 0.65, y: +0.41
ø9/32”
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
CENTER (0,0)
125B
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
BASS TREBLE
VOLUME DRIVE
FOOTSWITCHLED

PLASMA VINTAGE DRIVE 8
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

PLASMA VINTAGE DRIVE 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.

PLASMA VINTAGE DRIVE 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 cannotbe 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
1.0.1 (2020-07-20)
Updated link to parts list spreadsheet.
1.0.0 (2020-07-03)
Initial release.