2 layers293.3 × 128.5 mm
4 layers241.2 × 327.2 mm
Cyclic
tpcarlson/synth-diy107Mostly Eurorack projects
- Size
- 241.2 × 327.2 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 439
- Nets
- 653
- Pads
- 2,300
- Tracks, vias
- 6,049, 842
- Pours
- 19
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 16 Jan 2021
- Updated
- 19 Sep 2026
Overview
Cyclic is an open-source printed circuit board by tpcarlson, from the tpcarlson/synth-diy repository on GitHub. It is a 4-layer board of 241.2 × 327.2 mm with 439 parts on 653 nets, routed with 6,049 tracks and 842 vias.
It is built around the 74AHCT1G125SE, MMBT3904 and 1N4148W, with the ABM8-272-T3 among its other parts. Its parts include 165 capacitors, 139 diodes, 50 resistors, 27 connectors and 20 ICs. It belongs with the audio and music boards and the RP2350 boards of this library.
Main components
4
74AHCT1G125SE
SOT-353-40℃~+125℃ 1 1 4.5V~5.5V 4.7ns@5V,50pF 40uA 74AHCT 8mA 8mA Schmitt trigger Tri-State Unidirectional SOT-353 Buffers, Drivers, Receivers, Transceivers ROHSDiodes IncorporatedBuffers, Drivers, Receivers, Transceivers
MMBT3904
SOT-23-55℃~+150℃ 1 NPN 100 100nA 200mA 200mW 300MHz 300mV 40V 6V NPN SOT-23 Bipolar (BJT) ROHSJiangsu Changjing Electronics Technology (CJ)Bipolar (BJT)
1N4148W
SOD-123150mA 1A 1V@50mA 1uA@75V 400mW 4ns 75V Independent SOD-123 Switching Diodes ROHSSTMicroelectronicsSwitching Diodes
ABM8-272-T3
SMD3225-4P-40℃~+85℃ 10pF 12MHz 50Ω SMD crystal oscillator ±30ppm ±30ppm SMD3225-4P Crystals ROHSAbraconCrystals
README
vcadsr/README.mdVCADSR
What is this?
Voltage controlled ADSR, using the ElectricDruid EnvGen8 chip. The module provides voltage control over most parameters (Attack, decay, sustain, release, time, level) as well as manual control with sliders. There are also three switches for toggling the mode, linear/exponential, and a fifth stage called "punch" which adds a little bit more to the attack on an envelope.
The mode toggle switch allows for gated looping, just looping (Almost like an LFO), and normal ADSR mode.
How much power does it use?
As measured by the joranalogue Test 3, around 40mA on +12v and 30mA on -12v at peak. The 5v rail is unused.
Where does the design come from?
The schematic is really an extension of the reference design on the ElectricDruid site, with some changes to add LEDs, and cutting features that would otherwise take up more panel space than I was comfortable with - I dropped the attenuators for CV inputs in favour of nice big manual controls with linear potentiometers instead.
Are there any rare/weird parts used?
You'll need one of the EnvGen8 chips in order to make this function at all!
Are there any problems with the design?
Just a couple, which are corrected in the version here. First, the LEDs for gate and trigger had some issues drawing too much power due to an oversight in the schematic. As it turns out LEDs don't really like being driven without a resistor! Second, the panel design had the mode and linear/exponential graphics switched which makes operating it a little bit more confusing than it otherwise ought to be.
These problems are both fixed in the repository right now though, however the fixes are untested. If I make another run of these boards, I will verify that the fix worked and remove this whole section!
Do you have a BOM/Mouser cart/Tayda links?
Sorry, no. Things go out of stock so frequently it'd be a lot of work to keep these up to date. Everything in this project is easy to source though, so you should not have any trouble.
Other resources
- Assembly instructions
- Interactive BOM - This includes pre-soldered SMT parts as well as the through-hole parts. To use this, save the 'raw' view to your computer and open it in a web browser
Parts
439| Qty | Value | Footprint | References |
|---|---|---|---|
| 148 | 100n | Capacitor_SMD:C_0402_1005Metric | C10, C11, C100, C101, C102, C103, C104, C105, C106, C107, C108, C109, C110, C111, C113, C114 +132 |
| 128 | SK6812MINI-e (Reverse-mount) | Divergent Waves:SK6812-MINI-E (From github) | D10, D11, D100, D101, D102, D103, D104, D105, D106, D107, D108, D109, D110, D111, D112, D113 +112 |
| 17 | 10k | Resistor_SMD:R_0402_1005Metric | R11, R12, R13, R14, R15, R16, R17, R18, R21, R24, R27, R30, R33, R36, R39, R42 +1 |
| 16 | AudioJack2 | Divergent Waves:Jack_3.5mm_QingPu_WQP729JH-R-MONO | J5, J6, J7, J8, J9, J10, J11, J12, J13, J14, J15, J16, J17, J18, J19, J20 |
| 16 | ~ | Divergent Waves:ELAST_PAD_SQUARE_10MM_5.4MM_4X4GRID | SW3, SW4, SW5, SW6, SW7, SW8, SW9, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18 |
| 11 | 10u | Capacitor_SMD:C_0805_2012Metric | C5, C9, C21, C22, C40, C58, C76, C94, C112, C130, C148 |
| 9 | 74AHCT1G125 | Package_TO_SOT_SMD:SOT-23-5 | U3, U12, U13, U14, U15, U16, U17, U18, U19 |
| 8 | 100R | Resistor_SMD:R_0402_1005Metric | R20, R23, R26, R29, R32, R35, R38, R41 |
| 8 | 100k | Resistor_SMD:R_0603_1608Metric | R19, R22, R25, R28, R31, R34, R37, R40 |
| 8 | 1N4148 | Diode_SMD:D_SOD-323 | D133, D134, D135, D136, D137, D138, D139, D140 |
| 8 | MCP23S17_SO | Package_SO:SSOP-28_5.3x10.2mm_P0.65mm | U4, U5, U6, U7, U8, U9, U10, U11 |
| 8 | MMBT3904 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 |
| 8 | TestPoint | TestPoint:TestPoint_Plated_Hole_D2.0mm | TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8 |
| 4 | 4.7u | Capacitor_SMD:C_0805_2012Metric | C1, C4, C7, C8 |
| 2 | 15p | Capacitor_SMD:C_0402_1005Metric | C2, C3 |
| 2 | 1k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R43, R44 |
| 2 | 1k | Resistor_SMD:R_0805_2012Metric | R2, R3 |
| 2 | 27 | Resistor_SMD:R_0402_1005Metric | R7, R8 |
| 2 | 5.1k | Resistor_SMD:R_0402_1005Metric | R1, R4 |
| 2 | 500R | Resistor_SMD:R_0402_1005Metric | R9, R10 |
| 2 | 51R | Resistor_SMD:R_0805_2012Metric | R47, R48 |
| 2 | 51R | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R49, R50 |
| 2 | AudioJack3 | Divergent Waves:Jack_3.5mm_QingPu_WQP729JH-B-STEREO | J4, J21 |
| 2 | Conn_01x02_Pin | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J26, J27 |
| 2 | Conn_01x08_Pin | Connector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_Vertical | J22, J24 |
| 2 | Conn_01x08_Socket | Connector_PinSocket_2.54mm:PinSocket_1x08_P2.54mm_Vertical | J23, J25 |
| 2 | ESD | Diode_SMD:D_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1, D2 |
| 2 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H2, H3 |
| 2 | SW_Push | Button_Switch_THT:SW_Tactile_SPST_Angled_PTS645Vx39-2LFS | SW1, SW2 |
| 1 | 1N4148W | Diode_SMD:D_SOD-323 | D3 |
| 1 | 1k | Resistor_SMD:R_0402_1005Metric | R6 |
| 1 | 220R | Resistor_SMD:R_0402_1005Metric | R45 |
| 1 | 3.3u | Inductor_SMD:L_Cenker_CKCS201610 | L1 |
| 1 | 33 | Resistor_SMD:R_0402_1005Metric | R5 |
| 1 | 6N137 | Package_DIP:DIP-8_W7.62mm | U20 |
| 1 | ABM8-272-T3 | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | Barrel_Jack | Connector_BarrelJack:BarrelJack_Horizontal | J3 |
| 1 | Conn_01x03 | Connector_JST:JST_XH_S3B-XH-A-1_1x03_P2.50mm_Horizontal | J2 |
| 1 | NCP1117-3.3_SOT223 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U1 |
| 1 | RP2350_80QFN | Package_DFN_QFN:QFN-80-1EP_10x10mm_P0.4mm_EP3.4x3.4mm_ThermalVias | U2 |
| 1 | USB_C_Receptacle_USB2.0_16P | Divergent Waves:USB-C-SMD_G-SWITCH_GT-USB-9010AB | J1 |
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Questions
How big is the Cyclic PCB?
It measures 241.2 × 327.2 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Cyclic use?
439 parts, built around the 74AHCT1G125SE, MMBT3904, 1N4148W and ABM8-272-T3. 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 Cyclic KiCad files?
From the tpcarlson/synth-diy repository on GitHub, at the commit this page was made from: the board is cyclic/cyclic.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Cyclic design in my own project?
Its repository states no licence, so its author keeps all rights: ask tpcarlson before reusing the design.