Project idea
Build a secure access system where a 125 kHz RFID tag is read by an EM-18 module, the UID is compared against a stored whitelist on an 8051 board, and a relay energizes a 12 V solenoid door lock only when a valid tag is presented. Status is shown on a 16x2 character LCD as “AUTHORIZED” or “UNAUTHORIZED” for clear user feedback at the door panel.
Project description
The EM-18 outputs the tag’s ID over UART at 9600 bps, which the 8051 parses to match authorized IDs stored in code or EEPROM, then toggles a relay channel for lock control and updates the LCD in real time. A regulated 12 V adapter powers the lock while the 8051 and peripherals run at 5 V; the board’s serial/RS232 features make expansion (e.g., logging) straightforward. Future upgrade is simple with a GSM/SIM800-class modem on the board’s serial interface to SMS an alert whenever a tag is scanned.
Total list of components
8051 development board with AT89S52 and MAX232 (serial-ready)
EM-18 125 kHz RFID reader module (UART/Wiegand)
125 kHz RFID cards/key tags (at least 2 pieces)
16x2 character LCD display
1-channel 5 V relay module (opto-isolated preferred)
12 V DC solenoid door lock
12 V, 1 A SMPS adapter
Passive components: resistors, capacitors, diodes, transistors (for signal/power interfacing as needed)
LEDs, push buttons, slide/rocker switch
IC sockets as required
PCB or breadboard for prototyping
Cables and connectors (jumper wires, DC jack, headers)
Mini demo door hardware (panel + small hinge/latch) to mount the lock actuator
Features
Contactless RFID at 125 kHz using EM-18, with typical read distance up to a few centimeters and UART output at 9600 bps for easy 8051 parsing.
Clear 16x2 text feedback for AUTHORIZED/UNAUTHORIZED and system prompts, using standard HD44780-compatible LCD modules.
Electrically actuated 12 V solenoid lock driven via a 5 V relay module for safe MCU-level control of door hardware.
Ready for GSM upgrade via the 8051 board’s serial interface to send SMS alerts when tags are scanned.
Applications
Access control for labs, lockers, cabinets, classrooms, and small offices using passive RFID cards.
Attendance and audit logging variants by extending serial communications or adding external storage or modem modules.
Training kit for embedded C, UART parsing, relay driving, and HMI on resource-constrained 8051 systems.
Project Includes:
Fully assembled and tested circuit
Circuit diagram
Source code
(For DIY KITs - only the components will be provided)
Project Types:
- DIY KIT(Do IT YourSelf KIT) - We are providing only components in this kit for this project
- DIY KIT with Code & Circuit Connections - Along with the components, you will get the Code and the Circuit Connections file to help you build the project easily.
- Readymade Breadboard - We are providing fully assembled, tested and ready-made project using plug-n-play jumper wires and breadboard with all the other components, code & circuit diagram.
- Readymade Soldered - We are providing fully assembled, tested and ready-made project soldered on a PCB with all the other components, code & circuit diagram.
Shipping dimensions
Packed set with demo door panel typically fits a 20cm(L)×15CM(W)×10cm(H)
Weight
Solenoid locks alone are around 150 g for compact units; with 8051 board, LCD, relay, reader, cards, wiring, and adapter, the assembled demo typically ships at roughly 0.5–0.7 kg.
Estimate project weight
Expect about 1 kg including the adapter and demo mounting panel, dominated by the lock mass and power brick.
Notes: All the products are made by LearnElectronics India and not for re-sale.
