Digital Entry Lock

  
A keypad enters a four-digit access code, which is programmed via jumpers on a 24-pin plug-in header and socket. Ul is a
Digital Entry Lock - schematic

n LST220, which detects a four-digit sequential data input. When the correct data is entered into the keyboard, pin 13 of Ul goes high, which activates Ql and Kl. K1 drives an external electric lock solenoid, etc.




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