aion TERMINA User manual

TERMINA TRANSPARENT DRIVE 1
PROJECT NAME
TERMINA
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Timmy V2 / Vemuram Jan Ray
The original transparent overdrive, designed to bring out the best in the guitar and amplifier. Includes a
2-band tonestack for bass and treble control.
Overdrive 2.0.0 (2021-10-22)
BUILD DIFFICULTY
Easy
Actual size is 2.3” x 1.86” (main board) and 2.3” x 0.86” (bypass board).

TERMINA TRANSPARENT 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 Termina Transparent Drive is based on the Timmy overdrive pedal from Paul Cochrane, with some
modifications adapted from the Vemuram Jan Ray.
The Timmy was originally released in 2004 and is generally credited for kicking off the “transparent
overdrive” genre of pedals. It does have a two-band tone control, but generally speaking it’s not
designed to have much character of its own, instead bringing out the best qualities of the guitar and
amplifier. While it has some similarities to a stripped-down Tube Screamer, there is no trace of the
720Hz mid-hump the Tube Screamer is known for.
The Termina is more specifically based on the Timmy V2 with the clipping diode switch, which is the
same version that was licensed to MXR for their Custom Shop mini version. The Timmy V3 “15th
Anniversary” edition was released in 2019, moving the diode selector inside the pedal and repurposing
the toggle switch as a gain boost.
The Timmy has undergone several circuit changes throughout its run, so there is no single definitive
schematic. This excellent research article from ManticoreFX tracks all the known differences, with
several collected posts from Paul explaining the changes. The Termina project incorporates all of the
revisions prior to the V3 overhaul, while reversing the travel of the bass and treble knobs so they
increase the frequencies as they’re turned up instead of cutting as on the V2.
Please see page 10 for revised licensing terms, which are different from our normal projects. The
original Timmy pedal remains one of the best deals in the industry and we want to encourage as many
people as possible to buy the original if they are able.
USAGE
The Termina has four controls and one toggle switch:
• Drive controls the amount of gain from the op-amp stage that is clipped by the diodes.
• Bass allows adjustment of the pre-clipping bass response of the circuit.
• Treble allows adjustment of the post-clipping treble response of the circuit.
• Level sets the overall output of the effect.
• Clipping selects between three different sets of clipping diodes.

TERMINA TRANSPARENT 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 510k Metal film resistor, 1/4W
R2 3k3 Metal film resistor, 1/4W
R3 9k1 Metal film resistor, 1/4W Use 3k3 if omitting the bass trimmer mod.
R4 680R Metal film resistor, 1/4W Part of the bass trimmer mod. See build notes.
R5 1k Metal film resistor, 1/4W
R6 10k Metal film resistor, 1/4W
R7 10k Metal film resistor, 1/4W
R8 18k Metal film resistor, 1/4W
R9 8k2 Metal film resistor, 1/4W
R10 10k Metal film resistor, 1/4W
R11 100R Metal film resistor, 1/4W
RPD 2M2 Metal film resistor, 1/4W Input pulldown resistor.
LEDR 4k7 Metal film resistor, 1/4W LED current-limiting resistor. Adjust value to change LED brightness.
C1 39n Film capacitor, 7.2 x 2.5mm
C2 47pF MLCC capacitor, NP0/C0G
C3 100pF MLCC capacitor, NP0/C0G
C4 39n Film capacitor, 7.2 x 2.5mm
C5 1uF Film capacitor, 7.2 x 3.5mm
C6 10n Film capacitor, 7.2 x 2.5mm
C7 2n2 Film capacitor, 7.2 x 2.5mm
C8 1uF Film capacitor, 7.2 x 3.5mm
C9 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C10 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C11 100n MLCC capacitor, X7R Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 1N914 Fast-switching diode, DO-35
D3 1N914 Fast-switching diode, DO-35
D4 1N914 Fast-switching diode, DO-35
D5 1N914 Fast-switching diode, DO-35
D6 1N914 Fast-switching diode, DO-35
IC1 LM1458N Operational amplifier, DIP8 Can substitute JRC4559D (NJM4559D).
IC1-S DIP-8 socket IC socket, DIP-8

TERMINA TRANSPARENT DRIVE 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
BASS TRIM 10k trimmer Trimmer, 10%, 1/4” Part of the bass trimmer mod. See build notes.
GAIN 1MA 16mm right-angle PCB mount pot
BASS 50kC 16mm right-angle PCB mount pot
TREBLE 50kB 16mm right-angle PCB mount pot
VOLUME 25kA 16mm right-angle PCB mount pot
CLIP SPDT cntr off Toggle switch, SPDT center off
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.

TERMINA TRANSPARENT DRIVE 5
BUILD NOTES
Bass trimmer
This trimmer, along with R3 and R4, sets the frequency and gain ratio of the op-amp clipping stage. It
impacts both filters, including the range of the Bass knob.
Set it to about 45% rotation for the stock Timmy circuit (4.5k + 0.68k || 9.1k = 3.3k). Or, if you don’t care
to use this trimmer at all, you can use 3.3k for R3 and omit R4 and the trimmer entirely.
IC selection
The original Timmy has used both the JRC4559D and LM1458 throughout its production. Most V2’s
used the 4559, while the V3 now uses the 1458. Use a socket and try both of them to see which one you
like better.

SCHEMATIC
TERMINA TRANSPARENT DRIVE 6
GND
2M2
1N5817
100uF
1MA
50kB
GND
50kC
25kA
+9V
100n
VA
39n
510k
8k2
10k
VB
VB
GND
47uF
GND
47pF
GND
LM1458
LM1458
VA
GND
100R
100pF
3k3
9k1
680R
10kB
39n
VB
1uF
VB
1k
10n
GND
2n2
10k10k
VB
1uF
18k
GND
IN
OUT
RPD
D1
C10
1
2
3
GAIN
TREBLE
1
2
3
BASS
1
2
3
VOLUME
1
2
3
C11
C1
R1
R9
R10
C9
C2 2
3
1
IC1A
6
5
7
IC1B
84
R11
C3
D2 D3
D4D5
D6
CLIP
2
3
1
R2
R3
R4
BASS TRIM
1
2
3
C4
C5
R5
C6
C7
R6R7
C8
R8
GND

TERMINA TRANSPARENT 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.
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
CENTER (0,0)
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
125B
TREBLE BASS
VOLUME GAIN
FOOTSWITCHLED
CLIP
x: 0, y: +1.06
ø1/4”
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”
0 1 2
CM
0 1
INCH

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

TERMINA TRANSPARENT 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.

TERMINA TRANSPARENT 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.
This project is for personal use only and cannot be used for commercial endeavors in any quantity. You
can still sell your own personal builds if you no longer want them, but generally speaking, we don’t want
these DIY versions out on Reverb or eBay competing with the original Timmy.
The Timmy is still in production and remains one of the most reasonably-priced handmade pedals out
there, so please support the builder and buy one!
DOCUMENT REVISIONS
1.0.0 (2021-10-22)
Initial release.