Lock schematics

The digital lock shown below uses 4 common logic ICs to allow controlling a relay by entering a 4 digit number on a keypad. The first 4 outputs from the CD4017 decade counter (pins 3,2,4,7) are gated together with 4 digits from a keypad so that as the keys are depressed in the correct order, the counter will advance.... [read more]

A different circuit of electronic lock very simple, one and does not need a lot of materials in order to it is manufactured.... [read more]

It is a relatively simple circuit of electronic lock of safety with code of 7 digits. It should is given attention in the time that will be stepped the keys, that shape code and it does not exist it delays. With the right step of keys and if code is right then is activated exit Q7 for roughly 4 seconds, driving the transistor Q2, which with the line can drive one relay, for the opening of door, or any other circuit. With LED D we can have optical clue of activation. The code of circuit, as it has been given have been:1704570 but can change, if we change the connections between in the exits of IC1 and the switches.... [read more]

This circuit is designed to operate an electrical door-release mechanism - but it will have other applications. When you enter the four-digit code of your choice - the relay will energize for a preset time period. Use the relay contacts to power the release mechanism. The standby current is virtually zero - so battery power is a realistic option.... [read more]

This is a simplified version of the 4-Digit Keypad Controlled Switch. I have modified the design to reduce the complexity of the circuit - and the number of components required. As a result - the code is somewhat less secure. However, there should be lots of situations where it will still be adequate.... [read more]

This is a Universal version of the Four-Digit Alarm Control Keypad. I have modified the design to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. I've used a SPCO/SPDT relay - but you can use a multi-pole relay if you wish.... [read more]