One Transistor Electronic Code Lock System

This article presents a Electronic code door lock system using a transistor code lock circuit. We’ve already shown how an 8051 microcontroller may be used to create a password-based door lock system. Programming is required for such circuit. However, the most intriguing aspect of this circuit is that it may be completed without the use of any programming. This circuit is made up of just a transistor and a few buttons.

Outline

• One Transistor Electronic Code Lock System Circuit Principle:
• One Transistor Electronic Code Lock System Circuit Diagram:
  • Simple Transistor Code Lock Circuit Simulation Video:
  • One Transistor Electronic Code Lock System Circuit Design:
  • Simple Transistor Electronic Lock System Project Output Video:
  • How One Transistor Electronic Lock System Circuit Works?
  • Electronic Code Lock System Circuit Advantages and Applications:
    • Limitations of this Circuit:

One Transistor Electronic Code Lock System Circuit Principle:

This circuit’s main premise is that the door lock will only open if all of the buttons in series are hit at the same time. If any parallel button is pressed, the door is locked. When all of these buttons are pressed, the transistor activates the relay, which opens the door. These buttons can be placed in a specific order to open the door in real time.

One Transistor Electronic Code Lock System Circuit Diagram:

Circuit Components:

• Transformer.
• Bridge rectifier.
• Resistor.
• Capacitor.
• Buttons.
• Diode.
• Transistor.
• Relay.
• Motor
• Ac source.

Simple Transistor Code Lock Circuit Simulation Video:

One Transistor Electronic Code Lock System Circuit Design:

The circuit is made up of a stepdown transformer with a 230V and 50HZ AC supply as its input. The number of windings in the main coil of a stepdown transformer is smaller than the number of windings in the secondary coil.

The bridge rectifier is attached to it. The transformer’s full wave is rectified by the bridge rectifier. It contains four pins, two of which are wired to the transformer. The resistor and capacitor are linked to the other two pins, one of which is connected to ground and the other to the resistor and capacitor. The other end of the capacitor is grounded. Four buttons, S1, S2, S3, and S4, are connected in series to the resistor. They are now connected in parallel from the next button, S5.

In parallel with the buttons, a 100k resistor is connected. The transistor’s base is wired in parallel to the buttons. The transistor’s emitter pin is linked to ground. The 1N4007 diode is attached to the collector pin of the relay. The diode’s other end is linked to the relay’s one end. Because the relay creates back emf, a diode is utilised to safeguard the transistor. There are five pins on the relay. One pin is connected to the diode’s positive terminal. The ground pin is connected to the other pin. As a result, the relay output is connected to the motor via the AC source.

A magnetic relay is employed in this application. NC, NO, COM, A, B, NC, NO, COM, A, B, NC, NO, COM, A, B, NC, NO, COM, A, B, NC, NO, The coil’s inputs are A and B. When no voltage is given to these pins, the COM pin is linked to the NC pin, which is normally closed. When a DC voltage is given to the relay’s A and B pins, the COM pin is linked to the relay’s normally open pin, or NO pin.

Simple Transistor Electronic Code Lock System Project Output Video:

How One Transistor Electronic Code Lock System Circuit Works?

1. Apply a 230V and 50 HZ input voltage to the transformer at first.
2. As a result, the voltage is reduced to 6V by using a step down transformer.
3. The bridge rectifier receives this lower AC voltage. This generates a pulsing DC signal.
4. The output voltage is delivered to the buttons through a 2.2K ohm resistor.
5. Now hit switch S1 first, then switch S3 to complete the process.
6. Now push the S2 and S4 switches.
7. As the parallel buttons are opened, current travels via these switches to the transistor base.
8. The relay begins to switch, and the motor is connected to the supply.
9. The motor is now spinning, indicating that the door lock is open.

Electronic Code Lock System Circuit Advantages and Applications:

• This circuit is very simple, reliable and low cost.
• We can use it in security applications.
• We can also use it in door lock systems to open the door.

Limitations of this Circuit:

• If the user forgets the password i.e. the order of the buttons to be pressed it is difficult to open the lock.