Touch password lock switch circuit sharing

This touch operated electronic door lock can be used to lock any entryway by touching the keypad. The touch function of the lock is foolproof and impossible to crack because the touch function needs to be on all 3 programming pads together or at the same time, otherwise the lock will not respond.

Compared to the heavy metal keys we carry around, it is very convenient to use a code lock to open the door. Besides that, traditional keys can be easily misplaced, but this will not happen with a code lock.

Advantages of touch-operated password locks

The following circuit diagram shows a combination lock that can be opened with a valid three-digit code. However, this particular lock performs this function in an unconventional and unique technique. In this system, 3 digits must be touched simultaneously.

digits, which means three fingers must touch the 3 specified code buttons at the same time.

Any finger touching the incorrect button will not cause the relay to activate. As the diagram makes clear, it is virtually impossible for an intruder to deduce from the layout of the lock how to decode it.

This special feature, as well as the wide range of possible combinations, makes the code very difficult for an onlooker to crack. Another advantage is that

The fingers together help to cover the keyboard and hide the code operation from the onlooker, and the person finds it difficult to understand which 3 pads the owner has hit.

How it works

All 5 CMOS ICs are used here. All gates of IC 4050 are used as buffers and its inputs are connected with the touch keypad.

These buffers ensure that touch operations are effectively converted into logical output signals without glitches. Because our fingers may have different resistance levels and pressure, causing the output to oscillate and produce fluctuating outputs. The buffers ensure that this does not happen regardless of the touch variations.

The only criterion is the combination, which must be touched simultaneously to open the lock.

The output of the buffer is further connected with the hexagonal inverter IC 7404 and the processor IC

7430, 7410 connection, ultimately performing relay activation when the code is hit correctly. The electronic door opener can configure the relay contacts to achieve the opening and closing operations of the lock.

The code for the circuit diagram shown is 9-11-4. Whenever this program code pad is tapped simultaneously with a finger, the inputs of N2, N3, and N4 turn logical "0"; therefore, the three inputs of N8 and N5

Assuming no other keypad is tapped except the coded keypad, all inputs to gate N7 remain at logic "1", which causes the relay to be activated and the LED to turn on.

Illuminates. The relay can be used to operate the electric door opener to unlock.