Subscribe by email

Single button electronic lock circuit diagram electronic project

A very simple electronic lock that uses a single button to enter the code can be designed using electronic scheme in the figure below.
Electronic lock code consists of a series of long and short pulses, just like a Morse signal. The main part of circuit is an 8-bit shift register (IC1). Outputs of the integrated circuit are connected via switches S1 ... S8, the inverters N3 ... N10 and diodes D1 ... D8R based transistor T1 locking the control relay. T1 will enter in conduction only if there is a logic level "1" to the cathode of each diode. In all other cases, the current provided by R3 will be determined by one or more diodes. Switches are used to select normal or output the reverse of the register. With their secret code establishes that our scheme is 00,110,011.
When ring button is pressed, the relay activates and buzzer will sound . Meanwhile, the second relay contact will switch flip-flop made of N1 and N2. Output of N2 will generate clock signal to IC1 while N1 will command and MMV2 MMV1monostable multivibrators. The information read in the shift register is generated by MMV1 but is displaced in the register only after the N2 provides a positive pulse clock.
The second MMV serves as protection by deleting the shift register, if there is no pulse for five seconds. Pulse duration and waiting time can be changed by changing the value of R5 and R4 respectively.
The circuit is powered by a 5V voltage regulator and power consumption is determined by the type of relay used.

Circuit Diagram: 
Single button electronic lock circuit diagram part 1
Single button electronic lock circuit diagram part 2

Add new comment