# door alarm system ## Description 9 V reed-switch alarm schematic with BC547 transistor latch/driver, LED indicator, buzzer, power input, and reed switch input. ## Project Details - **Owner:** katealexia0 - **Created:** 5/15/2026 - **Last Updated:** 5/22/2026 - **Visibility:** Public ## Key Components ### BZ1 — [CPI-1375-80T](https://www.flux.ai/adrian95/cpi-1375-80t~np6.md) - Datasheet URL: https://www.cuidevices.com/product/resource/cpi-1375-80t.pdf - Role Details: Two-pin active buzzer connected between +9V and switched low-side transistor output; selected instead of 5V HNB09A05 because the reference circuit uses 9V - Manufacturer Name: Same Sky (Formerly CUI Devices) - Role: Signal Generation - Part Type: Buzzer - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: CPI-1375-80T **Pins:** - - [pin 2] - + [pin 1] ### J1 — [TerminalBlock-01x02P-5.00mm](https://www.flux.ai/vasy_skral/terminalblock-01x02p-500mm~h4.md) - Connector Positions: 2 - Part Type: Connector - Connector Type: Terminal Blocks - Role Details: +9 V and GND input terminal - Manufacturer Part Number: 282837-2 - Role: Power Conversion - Manufacturer Name: TE Connectivity **Pins:** - P1 [pin 2] - P2 [pin 1] ### J2 — [TerminalBlock-01x02P-5.00mm](https://www.flux.ai/vasy_skral/terminalblock-01x02p-500mm~h4.md) - Connector Positions: 2 - Connector Type: Terminal Blocks - Role Details: External reed switch input to ground - Part Type: Connector - Manufacturer Name: TE Connectivity - Manufacturer Part Number: 282837-2 - Role: Sensing (Shunt) **Pins:** - P1 [pin 2] - P2 [pin 1] ### LED1 — [LTL-307EE](https://www.flux.ai/vasy_skral/ltl-307ee~a2.md) - Role: Signal Generation - Role Details: Lights when the alarm output node is pulled low - Manufacturer Name: Lite-On Inc. - Datasheet URL: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/1153/LTL-307EE.pdf - Part Type: LED - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: LTL-307EE **Pins:** - A [pin 2] - K [pin 1] ### Q1 — [BC547](https://www.flux.ai/adrian95/bc547~ejc.md) - Manufacturer Part Number: BC547 - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/ON%20Semiconductor%20PDFs/BC546-50.pdf - Role Details: First transistor controlled by reed/timing node - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Transistor - Role: Switching - Manufacturer Name: onsemi **Pins:** - B [pin 2] - C [pin 1] - E [pin 3] ### Q2 — [BC547](https://www.flux.ai/adrian95/bc547~ejc.md) - Manufacturer Name: onsemi - Part Type: Transistor - Role: Switching - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/ON%20Semiconductor%20PDFs/BC546-50.pdf - Manufacturer Part Number: BC547 - Role Details: Sinks buzzer and LED current to ground **Pins:** - B [pin 2] - C [pin 1] - E [pin 3] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/katealexia0/door-alarm-system~72](https://www.flux.ai/katealexia0/door-alarm-system~72).* --- *Generated from [https://www.flux.ai/katealexia0/door-alarm-system~72](https://www.flux.ai/katealexia0/door-alarm-system~72)*