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POSITRON PREAMP DRIVE

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PROJECT NAME

POSITRON

BASED ON

EFFECT TYPE

PROJECT SUMMARY

DOCUMENT VERSION

Gorilla TC-35 Tube Cruncher

The preamp circuit of the Gorilla TC-35 amplifier adapted for use as an overdrive pedal.

Overdrive/preamp

1.0.0 (2020-06-05)

BUILD DIFFICULTY

Intermediate

Actual size is 2.3” x 1.86” (main board) and 1.78” x 0.86” (bypass board).

Summary of Contents for POSITRON

Page 1: ...CT SUMMARY DOCUMENT VERSION Gorilla TC 35 Tube Cruncher The preamp circuit of the Gorilla TC 35 amplifier adapted for use as an overdrive pedal Overdrive preamp 1 0 0 2020 06 05 BUILD DIFFICULTY Intermediate Actual size is 2 3 x 1 86 main board and 1 78 x 0 86 bypass board ...

Page 2: ...rdrive tone Interestingly there are no clipping diodes present and so all of the overdrive comes from overloading the opamp Typically this is an undesirable characteristic that is avoided but in this circuit it works The Positron is an adaptation of the TC 35 s preamp section It s a direct clone of the circuitry based on factory schematics running on the same voltage as the original but meant to b...

Page 3: ...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 100n Film capacitor 7 2 x 2 5mm C2 22n Film capacitor 7 2 x 2 5mm C3 2 2uF Film capacitor 7 2 x 5mm C4 10n Film capacitor 7 2 x 2 5mm C5 220pF MLCC capacitor NP0 C0G C6 2n2 Film capacitor 7 2 x 2 5mm C7 220n Film capacitor 7 2 x 2 5mm C8 22n Film...

Page 4: ...mm right angle PCB mount pot TREBLE 25kB 16mm right angle PCB mount pot VOL 1MB 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 ...

Page 5: ... GND 2u2 100k 10n GND 220pF 10k 2n2 GND 220n 22n 820R GND GND 1uF 47k GND TC1044SCPA 100uF PWR_GND VA 470n 100uF PWR_GND 10uF GND VA PWR_GND 10n 10n GND GND RPD D1 C11 DRIVE 1 2 3 MID 1 2 3 TREBLE 1 2 3 BASS 1 2 3 VOLUME 1 2 3 IN OUT C17 C1 R1 R2 2 3 1 IC1A 6 5 7 IC1B R3 R4 8 4 R5 C2 R6 R7 R8 C3 R9 C4 C5 R10 C6 C7 C8 R11 C9 R12 1 2 3 4 5 6 7 8 IC2 C13 C14 C10 C12 C15 C16 ...

Page 6: ...ame 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...

Page 7: ...POSITRON PREAMP DRIVE 7 ENCLOSURE LAYOUT Enclosure is shown without jacks See next page for jack layout and wiring 125B ...

Page 8: ...RAM 125B IN V GND GND N C OUT PCB IN GND V V JACK GND JACK OUT IN 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 ...

Page 9: ... 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...

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