2 layers80.2 × 100 mm
2 layers25.4 × 100 mm
VoltageProcessor
JopjeKnopje/VoltageProcessor1opamp based utility module for eurorack
- Size
- 25.4 × 100 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 31
- Nets
- 23
- Pads
- 95
- Tracks, vias
- 204, 55
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 26 Jul 2024
- Updated
- 19 Oct 2024
Overview
VoltageProcessor is an open-source printed circuit board by JopjeKnopje, from the JopjeKnopje/VoltageProcessor repository on GitHub. It is a 2-layer board of 25.4 × 100 mm with 31 parts on 23 nets, routed with 204 tracks and 55 vias.
It is built around the PJ301M-12. Its parts include 16 resistors, 6 capacitors, 5 connectors and 1 IC. It belongs with the audio and music boards of this library.
Main components
1README
README.mdVoltageProcessor
A eurorack module that outputs the sum and difference of two inputs, you can also add a constant DC offset to the summing output.
Motivation
The Beatstep Pro's pitch output cannot go lower than 2V, the VCO I'm using has a range of approximately 0-5V, so I had a way to subtract the 2V off of the pitch output. This module does just that, I intend to just use 1 CV input and a constant DC offset at -2V to achieve an output of 0V with a 2V input.
You could also use it as a small 2 -> 1 mixer.
Notes
This is my second KiCad project in a long time so the routing is not the best :)
Measured the current consumption at 1mA @ +12V and 7mA @ -12V
Bill of materials
| Reference | Value | Qty |
|---|---|---|
| C1,C2,C3,C4 | 0.1uF | 4 |
| C5,C6 | 47uF | 2 |
| J1,J2,J4,J5 | PJ301M-12 | 4 |
| J3 | Eurorack power | 1 |
| R1,R2,R3,R4,R5,R6,R7,R8,R9,R10,R11,R12 | 100k | 12 |
| R13,R14 | 1k | 2 |
| R15,R16 | 10k | 2 |
| RV1,RV2,RV3 | 100k | 3 |
| U1 | TL074 | 1 |
Schematic
KiCad renders
rev 0.2 -> 0.3 patches
- DC Offset potmeter range is now
+-10instead of the rail-rail voltage.
rev 0.1 -> 0.2 patches
- Flip eurorack power connector around y-axis, I currently use a flipped power cable as a workaround.
- Switch
U1BandU1Bterminals by adding jumper wire and cutting trace. - J4 and J5 output should be on pin 3 instead of pin 2. fix by adding jumper wire.
Todo
- All of the
rev 0.1 patches - Fix jack hole should be 6mm instead of 5.3mm.
- DC Offset potmeter compensate for opamp rail-rail offset which is around 1.3v
- Add polarity symbol in C5 and C6.
- Switch RV1 and RV2 twisting direction.
- Think about more ergonomic potmeter position.
- Front panel
- Produce and test rev 0.1
Resources
Parts
31| Qty | Value | Footprint | References |
|---|---|---|---|
| 12 | 100k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12 |
| 4 | 0.1uF | Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P2.50mm | C1, C2, C3, C4 |
| 4 | PJ301M-12 | Eurocad:PJ301M-12 | J1, J2, J4, J5 |
| 3 | 100k | libararies:trimmer_alps-rk09k1130ah1 | RV1, RV2, RV3 |
| 2 | 10k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R15, R16 |
| 2 | 1k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R13, R14 |
| 2 | 47uF | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C5, C6 |
| 1 | Eurorack power | Connector_IDC:IDC-Header_2x05_P2.54mm_Vertical | J3 |
| 1 | TL074 | Package_DIP:DIP-14_W7.62mm | U1 |
Questions
How big is the VoltageProcessor PCB?
It measures 25.4 × 100 mm and has 2 copper layers, 1.6 mm thick.
What parts does the VoltageProcessor use?
31 parts, built around the PJ301M-12. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the VoltageProcessor KiCad files?
From the JopjeKnopje/VoltageProcessor repository on GitHub, at the commit this page was made from: the board is VoltageProcessor.kicad_pcb and its schematic VoltageProcessor.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the VoltageProcessor design in my own project?
Its repository states no licence, so its author keeps all rights: ask JopjeKnopje before reusing the design.
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