Duress Code Alert System Variant 22 Kit with Arduino Uno + Relay
Duress Code Alert System Kit with Arduino Uno & Silent SMS Relay — Advanced Security Project
Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.
What if a keypad-locked door could send a silent alarm the moment someone forces you to open it? This kit brings that concept to life with a duress code alert system built on Arduino Uno. Enter one PIN and the relay clicks — the door appears to unlock normally. Enter a different, pre-set PIN and the relay still activates, but behind the scenes the SIM800L GSM module dispatches an SMS to a chosen number instantly, without any visible sign of alarm. It’s covert security engineered for real situations, from hostel rooms to private labs.
What You'll Build
You’ll assemble and program a fully functional dual-PIN security node. The 4x4 keypad reads entries against two stored codes — the “real” PIN triggers the 5V relay (simulating an electromagnetic door lock release) and the OLED shows a standard welcome message. The “duress” PIN performs the same unlock action but simultaneously fires a pre-composed SMS through the SIM800L module while the display stays innocuous. The system runs on a stable 5V power rail derived from a buck converter, decoupled with capacitors and mounted on a prototype PCB.
What You'll Learn
- Writing GSM AT command sequences to send SMS silently from an Arduino sketch
- Scanning and debouncing a 4x4 matrix keypad with pull-down resistors
- Driving a relay module safely and integrating it with a door-lock trigger logic
- Regulating input voltage with an LM2596 buck converter and designing noise-free power for GSM and OLED
- Displaying real-time status on a 0.96-inch OLED using I2C communication
- Planning multi-mode state machines in embedded C that handle stealth, normal, and alert conditions without conflict
Kit Contents
| Component | Quantity |
|---|---|
| Arduino Uno R3 | 1 |
| 4x4 Keypad | 1 |
| SIM800L GSM | 1 |
| 5V Relay Module | 1 |
| LM2596 Buck Converter | 1 |
| 0.96in OLED | 1 |
| 1000µF 25V Capacitor | 2 |
| 10kΩ Resistor | 5 |
| 100nF Capacitor | 5 |
| PCB Prototype Board | 2 |
| Soldering Iron | 1 |
| Solder Wire | 1 |
Why Buy This Kit Instead of Sourcing Parts Separately
| Factor | Sourcing Separately | Compoden Kit |
|---|---|---|
| Compatibility checks | You verify every part | Pre-tested as a system |
| Build support | Forums and scattered tutorials | AI companion trained on this exact project |
| Time to first working build | Days of debugging | Hours, with step-by-step guidance |
| Shipping coordination | Multiple sellers, multiple delays | One shipment from Bengaluru in 3-5 days |
Who This Kit Is For
B.Tech ECE and CSE students building IoT-security projects for their final year or Smart India Hackathon entries will find this kit directly aligns with their technical depth. CBSE Class 12 students with advanced robotics exposure and ATL Tinkering Lab mentors can use it for surveillance-stack demonstrations. Even PG hostel residents in campuses like VIT, BITS, or NIT experimenting with personal safety devices will appreciate the ready-to-solder parts and the clear, multi-mode code architecture.
Built and Backed by Compoden
Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.
What if I get stuck during the build?
Scan the QR code on the box to launch your AI build companion programmed for this exact project, or send a WhatsApp message to our support team for direct assistance.
Does the SIM800L need a separate SIM card?
Yes, you need a standard 2G-capable SIM with SMS plan. We recommend a prepaid Jio or Airtel 2G SIM, not included; the module supports 850/900/1800/1900 MHz bands.
Can I change the SMS alert text and phone number?
Absolutely. The Arduino sketch is fully commented, and you can edit the preset message and recipient number directly before uploading. The AI companion also shows you exactly which lines to modify.
How is the buck converter used here?
The LM2596 steps down a 7-12V input (from a wall adapter or battery) to a stable 5V that powers the Arduino, relay, OLED, and SIM800L simultaneously. The 1000µF caps smooth GSM transmit spikes.
Two PINs on keypad — real PIN unlocks, duress PIN sends silent SMS alarm while appearing to unlock.
What's in this kit
- Arduino Uno R3
- 4x4 Keypad
- SIM800L GSM
- 5V Relay Module
- LM2596 Buck Converter
- 0.96in OLED
- 1000µF 25V Caps x2
- 10kΩ Resistors x5
- 100nF Caps x5
- PCB Prototype Board x2
- Soldering Iron
- Solder Wire
Choose your assembly option:
- Soldering Kit — 25W soldering iron, 60/40 solder wire, flux, and small perfboard for permanent assembly.
- Breadboard Combo — 800-point full-size breadboard with 65-piece jumper wire pack for solderless prototyping.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items