combination lock in electronic

This is the circuit diagram of a combination lock electronic simple using CI LS7220. This circuit can be used to activate a relay to control (the & off) press any device when a preset combination of 4 digits. The circuit can be operated from 5V to 12V. Specify connection combination the appropriate parameters to pin 3, 4, 5 and 6 IC through the head

. As an example, if S1 is connected to pin 3 to pin 4, S2, S3, S4 to pin 5 to pin 6 IC, will the combination be 1234. This way we can create all the 4 digit combinations. Then connect the rest of the parameters to the leg 2 of the IC. This will cause IC reset If an invalid key is pressed, and the whole key code has to be entered. When the right key is pressed, the out put (relay) for a period of time is determined be enabled by the capacitor C1. Here, it should be 6s. Temporary increase increase C1.

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