PARASIT STUDIO 1985 Technical manual

1985
Guitar Synthesizer
Build Document last updated december 2018
Version 1.0 2018
The 1985 Guitar Synth is a Attiny85 microcontroller-based square
ave guitar synth/fuzz ith both octave do n, octave up and
detuned modes. The octave up oscillator is based on a frequency
counter and sounds super glitchy, like a malfunctioning R2-D2...
The octave do n oscillator is much more controlled. This is the first
Parasit Studio DIY project that is fully digital and that allo ed for
adding a fun hidden feature as ell... :-)
Happy building and playing!
PLEASE NOTE!
This project requires programming. You can get pre-programmed chips
together with the P B from the Parasit Studio webshop or included with
the Musikding kit. You can also program your own Attiny85 chips if you
know how and have the required interface and software. You can find
the HEX files needed at www.parasitstudio.se

CONTROLS
POTENTIOMETERS
•DOWN – The level of the octave do n
•UNISON – The level of the unison square ave
•UP – The level of the octave up
The unison is the direct fuzz which works well with chords. This is
unaffected by the other controls.
SWITCHES
•OCTAVE DOWN - toggle bet een:
◦One octave do n
◦Detuned (in bet een one and t o octaves do n)
◦T o octaves do n
The detune is the input signal divided by 3.
•OCTAVE UP – toggles the sa :
◦One octave up
◦Detuned (in bet een one and t o octaves up)
◦Unison ( ith a slight detune)
The one octave up mode is very glitchy and won't stay in tune for
the entire fretboard, but that's part of the fun... The Unison mode
is slightly detuned to give you a layered and phasey sound when
blended with the direct fuzz.

General builds tips
•Solder the lo profile components first, from short to tall
height. Recommended order: resistors, diodes, IC socket, film-
caps, electrolytics, pots and s itches
•IC chips are sensitive to static charges and can be easily
damaged. It's a good idea to ear a anti-static ristband or at
least avoid earing a ool jumper and petting your cat/dog
hile building...
•Al ays use sockets for IC chips and transistors to avoid
heating them directly. It also makes it much easier to s ap
them out if needed.
•Pay special attention to the orientation of the IC's, diodes and
electrolytics.
•The square pad represents pin 1 of the pot.
•This PCB's is designed for 16mm Alpha PCB mounted angeled
pots. You could also use solder lug type and just tack some
“legs” ith short pieces of ire to the pot to mimic a PCB
mount type.
•Mount the pots and the s itches to the back side (solder side)
of the PCB and solder them from the front side (component
side).
•Cover the back of the pots ( ith pot covers or tape or a piece
of carbon) so that they don't create a short on the PCB.
Wirin
For more info on ho to ire up the stomps itch, jacks ect, please
visit the Parasit Studio ebsite and do nload the PDF called
”offboard iring”. You can find it here:
http:// .parasitstudio.se/build-docs.html

1985 Guitar Synth Bill Of Materials (BOM)
BOM NOTES
•Use multilayer ceramic capacitors for C9 & C10 (important!)
•* R11 is a Current Limiting Resistor for the bypass LED. Use
the appropriate value for your LED type. For diffused LED's I
recommend using a 4.7K resistor, and for clear superbright
LED's I recommend a 15K resistor.
•** The reset s itch is optional and not really needed. It ill
reset the pedal hich ill restart the hidden feature
(depending on the other s itches). Use a momentary normally
open s itch.
Other thin s not included in the BOM but ood to have:
enclosure, input and output jacks, DC jack, led bezels, 3PDT s itch
and knobs.
Resistors Capacitors IC's
R1 10K C1 100nF U1 Attiny85 20PU
R2 1M C2 10nF U2 Attiny85 20PU
R3 470K C3 22uF
R4 10K C4 2.2uF Potentiometers
R5 100K C5 1uF OCTAVE DOWN A100K
R6 100K C6 1nF UNISON A100K
R7 100K C7 100nF OCTAVE UP A100K
R8 100K C8 22uF
R9 10K C9 100nF Switches
R10 4.7K C10 100nF DOWN SPDT on/off/on
R11 CLR* UP SPDT on/off/on
Diodes RESET Momentary SPST **
D1 1N4001
D2 1N4148 Transistor(s)
D3 1N4148 Q1 78L05
1x LED Q2 2N3904

Drillin template (1590B)
•This template is approximate. Use at your o n risk!
•Make sure your printer isn't doing any scaling / is set to 100%
print size.
•Drill the DC jack and input/output jacks (and the optional
reset s itch) to your o n preference.
•The LED hole here is 6mm, for using a 3mm LED ith a bezel.
•Measure and confirm before drillin !

Schematic

Troubleshootin
There's al ays a chance of running into trouble. To minimize error,
follo the BOM and general building tips carefully. Take your time
and don't rush. Take a break no and then. Use good solder, and it
helps to have a decent soldering station insted of a cheap iron.
If you are still having trouble, please visit the madbean forum
Parasit Studio subforum section and ask for help there.
http:// .madbeanpedals.com/forum/index.php?board=84.0
If you have bought the Musikding kit and have recieved a faulty or
missing component, please contact musikding directly.
https:// .musikding.de/kontakt.php?lang=eng
Terms of use
PCB's from Parasit Studio are intended for DIY use only. Commersial resale is
not allo ed. It's meant for personal use only, hich means that it's not allo ed
to build alot of pedals and sell them for profit to strangers using public forums
and craiglist ads. Ho ever, it's totally ok to build a fe pedals and sell to your
friends and bandmates. After all, that's hat this hobby is about. DIY or DIE!
www.parasitstudio.se
parasitstudio@ mail.com