# Eurorack Sawtooth Core VCO ## Description Professional Eurorack sawtooth-core VCO with discrete 2N3904/2N3906 exponential converter, TL072 square comparator, plus/minus 12 volt rails, precision passives, and a low-bleed 2-layer 100 mm by 50 mm layout. ## Project Details - **Owner:** pxclchl - **Created:** 4/15/2026 - **Last Updated:** 4/15/2026 - **Visibility:** Public ## Key Components ### J1 — [2x5 Pin Shrouded Header](https://www.flux.ai/rex-flux/2x5-pin-shrouded-header.md) - Manufacturer Name: Würth Elektronik - Manufacturer Part Number: 61201021621 - Role Details: Eurorack plus and minus 12 volt power entry - Role: Power input connector - Datasheet URL: https://www.we-online.com/catalog/datasheet/61201021621.pdf - Part Type: Connector - Package: 2x5 2.54mm TH **Pins:** - P1 [pin 1] - P10 [pin 10] - P2 [pin 2] - P3 [pin 3] - P4 [pin 4] - P5 [pin 5] - P6 [pin 6] - P7 [pin 8] - P7 [pin 7] - P9 [pin 9] ### J2 — [PJ-301BM](https://www.flux.ai/dominic-dev/pj-301bm.md) - Role: Panel I/O jack - Part Type: Connector - Role Details: Used for control voltage input and waveform outputs - Purchase Url: https://www.aliexpress.com/item/1005001958349207.html - Connector Type: Audio / Video Connectors - Package: Vertical TH 3.5mm jack - Datasheet URL: http://www.taydaelectronics.com/datasheets/files/A-2566.pdf **Pins:** - S1 - S2 - T - TN ### J3 — [PJ-301BM](https://www.flux.ai/dominic-dev/pj-301bm.md) - Part Type: Connector - Role Details: Used for control voltage input and waveform outputs - Purchase Url: https://www.aliexpress.com/item/1005001958349207.html - Connector Type: Audio / Video Connectors - Package: Vertical TH 3.5mm jack - Role: Panel I/O jack - Datasheet URL: http://www.taydaelectronics.com/datasheets/files/A-2566.pdf **Pins:** - S1 - S2 - T - TN ### J4 — [PJ-301BM](https://www.flux.ai/dominic-dev/pj-301bm.md) - Package: Vertical TH 3.5mm jack - Datasheet URL: http://www.taydaelectronics.com/datasheets/files/A-2566.pdf - Role: Panel I/O jack - Purchase Url: https://www.aliexpress.com/item/1005001958349207.html - Connector Type: Audio / Video Connectors - Role Details: Used for control voltage input and waveform outputs - Part Type: Connector **Pins:** - S1 - S2 - T - TN ### Q1 — [2N3904TFR](https://www.flux.ai/adrian95/2n3904tfr.md) - Role Details: Used in matched NPN pair for expo converter plus one NPN reset device - Manufacturer Part Number: 2N3904TFR - Datasheet URL: https://www.onsemi.com/pdf/datasheet/pzt3904-d.pdf - Package: TO-92 - Role: Exponential converter and reset transistor - Part Type: Transistor - Manufacturer Name: onsemi - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - B [pin 2] - C [pin 1] - E [pin 3] ### Q2 — [2N3904TFR](https://www.flux.ai/adrian95/2n3904tfr.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi - Part Type: Transistor - Role Details: Used in matched NPN pair for expo converter plus one NPN reset device - Role: Exponential converter and reset transistor - Manufacturer Part Number: 2N3904TFR - Package: TO-92 - Datasheet URL: https://www.onsemi.com/pdf/datasheet/pzt3904-d.pdf **Pins:** - B [pin 2] - C [pin 1] - E [pin 3] ### Q3 — [2N3904TFR](https://www.flux.ai/adrian95/2n3904tfr.md) - Role: Exponential converter and reset transistor - Role Details: Used in matched NPN pair for expo converter plus one NPN reset device - Datasheet URL: https://www.onsemi.com/pdf/datasheet/pzt3904-d.pdf - Manufacturer Part Number: 2N3904TFR - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi - Part Type: Transistor - Package: TO-92 **Pins:** - B [pin 2] - C [pin 1] - E [pin 3] ### Q4 — [2N3906TA](https://www.flux.ai/lcsc/2n3906ta.md) - Product Info Url: https://lcsc.com/product-detail/Transistors-NPN-PNP_ON-Semicon_2N3906TA_ON-Semicon-ON-2N3906TA_C258186.html - Role Details: Used in expo current source and reset support - Role: PNP transistor stage - Package or Case Code: TO-92-3_L4.9-W3.7-P2.54-L - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1810120035_onsemi-2N3906TA_C258186.pdf - LCSC Part Number: C258186 - Package: TO-92 - Manufacturer Part Number: 2N3906TA - Manufacturer Name: onsemi(安森美) - JLCPCB Part Class: Extended Part - Part Type: Bipolar Transistors - BJT **Pins:** - B [pin 2] - C [pin 3] - E [pin 1] ### Q5 — [2N3906TA](https://www.flux.ai/lcsc/2n3906ta.md) - Role: PNP transistor stage - Package: TO-92 - Manufacturer Name: onsemi(安森美) - Manufacturer Part Number: 2N3906TA - JLCPCB Part Class: Extended Part - Part Type: Bipolar Transistors - BJT - Product Info Url: https://lcsc.com/product-detail/Transistors-NPN-PNP_ON-Semicon_2N3906TA_ON-Semicon-ON-2N3906TA_C258186.html - Role Details: Used in expo current source and reset support - Package or Case Code: TO-92-3_L4.9-W3.7-P2.54-L - LCSC Part Number: C258186 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1810120035_onsemi-2N3906TA_C258186.pdf **Pins:** - B [pin 2] - C [pin 3] - E [pin 1] ### U1 — [TL072IP](https://www.flux.ai/jecstronic/tl072ip.md) - Datasheet URL: https://www.ti.com/lit/ds/symlink/tl072a.pdf - Role: Square comparator - Part Type: Integrated Circuit - Manufacturer Part Number: TL072IP - Manufacturer Name: Texas Instruments - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Generates the 0V to 5V square output from the saw waveform - Package: PDIP-8 **Pins:** - -VCC [pin 4] - 1IN- [pin 2] - 1IN- [pin 6] - 1IN+ [pin 3] - 1OUT [pin 1] - 2IN+ [pin 5] - 2OUT [pin 7] - VCC+ [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/pxclchl/eurorack-sawtooth-core-vco](https://www.flux.ai/pxclchl/eurorack-sawtooth-core-vco).* --- *Generated from [https://www.flux.ai/pxclchl/eurorack-sawtooth-core-vco](https://www.flux.ai/pxclchl/eurorack-sawtooth-core-vco)*