# Gigantic White P.K.E. Meter ## Description 9V Beam-Break Alarm Circuit Using LDR, LM393 Comparator with Hysteresis, and Adjustable Sensitivity ## Project Details - **Owner:** zedrak - **Created:** 10/9/2025 - **Last Updated:** 10/9/2025 - **Visibility:** Public - **System Architecture:** ```mermaid graph TD; Battery -- VCC,GND --> LM393; LM393 --> LDR_divider; LDR_divider --> Comparator; Comparator --> Hysteresis; Hysteresis --> Pull_up; Pull_up --> NPN_driver; NPN_driver --> LED_and_Buzzer; ``` ## Key Components ### BZ1 — [CPI-1514-12-95T](https://www.flux.ai/adrian95/cpi-1514-12-95t~x3q.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Same Sky (Formerly CUI Devices) - Role Details: Audible beam-break alarm - Datasheet URL: https://www.cuidevices.com/product/resource/cpi-1514-12-95t.pdf - Manufacturer Part Number: CPI-1514-12-95T - Role: Alert - Part Type: Buzzer **Pins:** - - [pin N] - + [pin P] ### D1 — [LED-THT-3MM](https://www.flux.ai/vasy_skral/led-tht-3mm~34u.md) - Part Type: LED - Role: Indicator - Role Details: Visual beam-break indicator **Pins:** - A [pin 2] - K [pin 1] ### J1 — [968](https://www.flux.ai/adrian95/968~4al.md) - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.keyelco.com/userAssets/file/M65p31.pdf - Role Details: 9V battery snap connector - Part Type: Battery Connector - Package or Case Code: BAT_968 - Manufacturer Name: Keystone - Role: Connector - Manufacturer Part Number: 968 **Pins:** - N [pin N] - P [pin P] ### Q1 — [2N2222A](https://www.flux.ai/lcsc/2n2222a~00rk.md) - Role: Switching - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1809200018_ST-Semtech-2N2222A_C118536.pdf - Manufacturer Part Number: 2N2222A - JLCPCB Part Class: Extended Part - Role Details: Low-side switch for LED and buzzer - LCSC Part Number: C118536 - Manufacturer Name: ST(先科) - Transistor Type: NPN - Package or Case Code: TO-92-3_L4.9-W3.7-P1.27-L - Compliance: RoHS - Product Info Url: https://lcsc.com/product-detail/Transistors-NPN-PNP_2N2222_C118536.html - Part Type: Transistors/Thyristors/Bipolar (BJT) - Frequency: 250MHz **Pins:** - B [pin 2] - C [pin 3] - E [pin 1] ### U1 — [LM393DRG3](https://www.flux.ai/lcsc/lm393drg3~xoj.md) - Manufacturer Part Number: LM393DRG3 - Part Type: Comparators - Role Details: Beam-break threshold comparator - LCSC Part Number: C543057 - Role: Comparator - Package or Case Code: SOIC-8_L4.9-W3.9-P1.27-LS6.0-BL - Manufacturer Name: TI(德州仪器) **Pins:** - 1IN+ [pin 3] - 1IN− [pin 2] - 1OUT [pin 1] - 2IN+ [pin 5] - 2IN− [pin 6] - 2OUT [pin 7] - GND [pin 4] - VCC [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/zedrak/gigantic-white-ppkpep-meter~ak](https://www.flux.ai/zedrak/gigantic-white-ppkpep-meter~ak).* --- *Generated from [https://www.flux.ai/zedrak/gigantic-white-ppkpep-meter~ak](https://www.flux.ai/zedrak/gigantic-white-ppkpep-meter~ak)*