The most code switch will be a key number 1 to 10 is good. But when I press a number key often until has track, making it possible to guess the code.
This circuit use the normal door bell switch is the code enter. The code include pulse short and long like the mos code. IC1 shift register or 8 bit data slider. The output of this ICs is connected with S1 to S8. By through the inverter N3 to N10. Then, through diode D1 to D8 to base of T1 to control the door locker, By T1 will work when has logic is “1” at all diodes. Otherwise, the base current from R3 to flow through the diode that get logic “0” at cathode to ground.
Switches S1 to S8 are used to select output of IC1 that Passed dormant or are reversed logic, this is code setting. In the circuit the position of the all switches will be the code 00110011. When the switch is pressed the door bell ring and the bell rings.
At the same time, the contact of the relay 2 will be entered the code to bistable. Which include N1 and N2, the output of N2 will be code transmitter to IC1. The N1 will to trigger the monostable multivibrator MMV1 and MMV2. The data that read from MMV1 will be sent to IC1. But the data will move, the N2 provide the pulse clock before, The Bell of the switch is released.
The times range of monostable MMV1 short of half a second. If bell switch is released during this period, IC1 reads as “0”. If longer be read as a “1” because one of MMV1 Q is “1” again.
This way is entered the code to IC1,The MMV 2 served reset shift register. If no pulse into another. After 5 seconds, the circuit will lock again. Time of the pulse and reset time changed by changing the R5 and R4, respectively. This circuit consumes 5 volts from the regulator IC modulation and the rate of consumption depends on the type of relay used.
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