# NF-Universal Alarm ## Description Best-effort NF-UNIVERSAL ALARM schematic recreation from image, with MCP73831 Li-ion charging, dual 555 timers, transistor switching, LEDs, switches, and flagged uncertainties. ## Project Details - **Owner:** fatenerris - **Created:** 5/4/2026 - **Last Updated:** 5/11/2026 - **Visibility:** Public - **Copies:** 2 ## Key Components ### BZ1 — [Buzzer](https://www.flux.ai/jecstronic/buzzer~1j2.md) - Manufacturer Name: Adafruit Industries LLC - Part Type: Buzzer - Sound Pressure Level: 85dB - Frequency: 4kHz - Voltage Rating: 5V - Package or Case Code: Through-hole buzzer, 12mm dia, RM7.6mm / 0.3in pin spacing - Digi-Key Part Number: 1528-1536-ND - Manufacturer Part Number: 1536 - Datasheet URL: https://cdn-shop.adafruit.com/product-files/1536/C1888-001_datasheet.pdf - Implementation Notes: Internally driven piezo buzzer; apply DC voltage, no external oscillator required. Adafruit product page states 3V–5V usable and tone cannot be changed. Polarity was not specified on the Digi-Key page; verify +/− marking on the physical part/datasheet before wiring. - Current Rating: 15mA - Operating Voltage Range: 4–8 V **Pins:** - - - + ### D1 — [1N4148W-E3-18](https://www.flux.ai/lcsc/1n4148w-e3-18~v9hp.md) - Manufacturer Name: VISHAY(威世) - Datasheet URL: https://lcsc.com/product-detail/Others_Vishay-Intertech_1N4148W-E3-18_Vishay-Intertech-1N4148W-E3-18_C191428.html - Role Details: D1 type/orientation unreadable; 1N4148W used as best-effort substitute - Role: Diode - JLCPCB Part Class: Extended Part - Part Type: Switching Diode - Manufacturer Part Number: 1N4148W-E3-18 - LCSC Part Number: C191428 - Package or Case Code: SOD-123_L2.7-W1.6-LS3.7-FD - Product Info Url: https://lcsc.com/product-detail/Others_Vishay-Intertech_1N4148W-E3-18_Vishay-Intertech-1N4148W-E3-18_C191428.html **Pins:** - A [pin 1] - K [pin 2] ### J1 — [0473460001](https://www.flux.ai/adrian95/0473460001~d9a.md) - Role: USB Input - Role Details: USB connector extracted as SH1 with VCC D- D+ ID GND and shield; exact connector MPN uncertain - Manufacturer Part Number: 0473460001 - Part Type: Connector - Datasheet URL: https://tools.molex.com/pdm_docs/sd/473460001_sd.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Molex **Pins:** - D- [pin 2] - D+ [pin 3] - GND [pin 5] - ID [pin 4] - SHIELD [pin S6] - SHIELD [pin S5] - SHIELD [pin S2] - SHIELD [pin S4] - SHIELD [pin S3] - SHIELD [pin S1] - VBUS [pin 1] ### J2 — [JST B2B PH K 01x02 Connector](https://www.flux.ai/jharwinbarrozo/jst-b2b-ph-k-01x02-connector~zu5.md) - Manufacturer Name: JST Sales America - Datasheet URL: https://www.jst-mfg.com/product/pdf/eng/ePH.pdf - Manufacturer Part Number: B2B-PH-K-S(LF)(SN) - Part Type: Connector **Pins:** - PIN1 [pin 1] - PIN2 [pin 2] ### LED1 — [SML-LX0603GW-TR](https://www.flux.ai/adrian95/sml-lx0603gw-tr~uqi.md) - Manufacturer Name: Lumex Opto/Components Inc. - Role: Indicator - Manufacturer Part Number: SML-LX0603GW-TR - Part Type: LED - Role Details: LED color/orientation unreadable; generic 0603 indicator LED used - Datasheet URL: https://www.lumex.com/spec/SML-LX0603GW-TR.pdf - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - A [pin 2] - K [pin 1] ### LED2 — [SML-LX0603GW-TR](https://www.flux.ai/adrian95/sml-lx0603gw-tr~uqi.md) - Role: Indicator - Manufacturer Part Number: SML-LX0603GW-TR - Manufacturer Name: Lumex Opto/Components Inc. - Part Type: LED - Role Details: LED color/orientation unreadable; generic 0603 indicator LED used - Datasheet URL: https://www.lumex.com/spec/SML-LX0603GW-TR.pdf - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - A [pin 2] - K [pin 1] ### LED3 — [LED 0805 (2012 Metric)](https://www.flux.ai/vasyl/led-0805-2012-metric~sr7.md) - Role: Indicator - Current Rating: 30mA - Operating Temperature: -40°C to +80°C - Role Details: White 0805 LED; pin 1 anode, pin 2 cathode; intended exact MPN QBLP631-IW5 using Flux 0805 LED template. - Datasheet URL: https://www.qt-brightek.com/datasheet/QBLP631-IW5.pdf - Manufacturer Part Number: QBLP631-IW5 - Manufacturer Name: QT Brightek (QTB) - Package or Case Code: SMD_0805_2012Metric - Max Reverse Voltage: 5V - Forward Voltage: 2.5–3.4V - Part Type: LED **Pins:** - A [pin 2] - K [pin 1] ### Q1 — [BSS138](https://www.flux.ai/vasy_skral/bss138~3ld.md) - Implementation Details: Placeholder BSS138 selected as a common N-channel SOT-23 MOSFET for low-side switching. Confirm whether N-channel source-to-GND/drain-to-R8/VCC is correct for BATTERYCUTOFF before fabrication. - Transistor Type: N-channel MOSFET - Manufacturer Part Number: BSS138 - Role Details: Replaces Q1 MMBT3904LT1G BJT in BATTERYCUTOFF block. Intended functional mapping: gate = old base/BATTERYCUTOFF control network, source = old emitter/GND, drain = old collector/VCC/R8 side. MOSFET type/orientation/pin mapping is uncertain from image-derived source; review required. - Role: Switching - Datasheet URL: https://www.onsemi.com/pdf/datasheet/bss138-d.pdf - Part Type: Transistor - Manufacturer Name: onsemi **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q2 — [BSS138](https://www.flux.ai/vasy_skral/bss138~3ld.md) - Transistor Type: N-channel MOSFET - Manufacturer Part Number: BSS138 - Implementation Details: Placeholder BSS138 selected as a common N-channel SOT-23 MOSFET for low-side switching. Confirm whether N-channel source-to-GND/drain-to-R8/VCC is correct for BATTERYCUTOFF before fabrication. - Datasheet URL: https://www.onsemi.com/pdf/datasheet/bss138-d.pdf - Role: Switching - Role Details: Replaces Q1 MMBT3904LT1G BJT in BATTERYCUTOFF block. Intended functional mapping: gate = old base/BATTERYCUTOFF control network, source = old emitter/GND, drain = old collector/VCC/R8 side. MOSFET type/orientation/pin mapping is uncertain from image-derived source; review required. - Part Type: Transistor - Manufacturer Name: onsemi **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### SW1 — [SW-18010P](https://www.flux.ai/lcsc/sw-18010p~lhmi.md) - Part Function: Fast vibration sensor switch, SPST normally open spring-vibration trigger - Manufacturer Name: SHOU HAN(首韩) - JLCPCB Part Class: Extended Part - Part Type: Vibration Sensors - Package or Case Code: SW-TH_SW-18010P - LCSC Part Number: C2681585 - Uncertainty: Exact Flux library part/footprint for Adafruit 1766 was not found. SW-18010P is used as a 2-pin through-hole vibration switch placeholder; verify lead spacing and mechanical can dimensions before PCB fabrication. - Datasheet URL: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/2201/1766_Web.pdf - Manufacturer Part Number: 1766 - Manufacturer: Adafruit Industries LLC - Digi-Key Part Number: 1528-1766-ND **Pins:** - 1 [pin 1] - 2 [pin 2] ### SW2 — [EG1213](https://www.flux.ai/lcsc/eg1213~j3ux.md) - Notes: Datasheet shows terminal 2 is common, switched between terminals 1 and 3; footprint has 3x 0.70mm terminal holes on 2.00mm pitch plus 2x 1.40mm mounting holes spaced 9.70mm. - Datasheet URL: https://configured-product-images.s3.amazonaws.com/Datasheets/EG.pdf - Current Rating: 200mA - JLCPCB Part Class: Extended Part - Product Info Url: https://lcsc.com/product-detail/Others_E-Switch_EG1213_E-Switch-EG1213_C273393.html - Manufacturer Name: E-Switch - Mounting Type: Through Hole, Right Angle - Voltage Rating: 30V - Circuit: SPDT - LCSC Part Number: C273393 - Package or Case Code: SW-TH_EG1213 - Manufacturer Part Number: EG1213 - Part Type: Slide Switch **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] ### U1 — [MCP73831T-2ATI/OT](https://www.flux.ai/adrian95/mcp73831t-2atiot~46p.md) - Part Type: Integrated Circuit - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: MCP73831T-2ATI/OT - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/MCP73831-Family-Data-Sheet-DS20001984H.pdf - Role: Battery Charger - Manufacturer Name: Microchip Technology - Role Details: U1 MCP73831 visible in image; exact suffix/package assumed SOT-23-5 MCP73831T-2ATI/OT **Pins:** - PROG [pin 5] - STAT [pin 1] - VBAT [pin 3] - VDD [pin 4] - VSS [pin 2] ### U2 — [NE555D](https://www.flux.ai/kicad-part-library/ne555d~p5.md) - Package or Case Code: SOIC-8_3.9x4.9mm_P1.27mm - Role: Timer - Datasheet URL: http://www.ti.com/lit/ds/symlink/ne555.pdf - Manufacturer Part Number: NE555D - Role Details: 555 timer block visible as U2; exact part/package uncertain, NE555D SOIC-8 used as substitute - Manufacturer Name: Texas Instruments Inc. **Pins:** - CV [pin 5] - DIS [pin 7] - GND [pin 1] - Q [pin 3] - R [pin 4] - THR [pin 6] - TR [pin 2] - VCC [pin 8] ### U3 — [NE555D](https://www.flux.ai/kicad-part-library/ne555d~p5.md) - Manufacturer Name: Texas Instruments Inc. - Role Details: 555 timer block visible as U2; exact part/package uncertain, NE555D SOIC-8 used as substitute - Manufacturer Part Number: NE555D - Datasheet URL: http://www.ti.com/lit/ds/symlink/ne555.pdf - Role: Timer - Package or Case Code: SOIC-8_3.9x4.9mm_P1.27mm **Pins:** - CV [pin 5] - DIS [pin 7] - GND [pin 1] - Q [pin 3] - R [pin 4] - THR [pin 6] - TR [pin 2] - VCC [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/fatenerris/nf-universal-alarm~xe](https://www.flux.ai/fatenerris/nf-universal-alarm~xe).* --- *Generated from [https://www.flux.ai/fatenerris/nf-universal-alarm~xe](https://www.flux.ai/fatenerris/nf-universal-alarm~xe)*