Question by Ivica M: Electronic lock help?
In the circuit given here: http://www.elektronika.ba/el.sheme/fajlovi/r86.gif
“when all keys have been pressed in correct order Q7 goes high for about four seconds to drive the “unlock” circuitry (a relay driver for an automatic door opener).
Can anyone tell me how can i connect that relay driver? And how to connect LEDs (green if the keys are pressed in correct order, and Red if they are not).
Please help me to solve this problem.
Answer by stratsandlespauls
Q7 will require a transistor to drive the relay.
Take Q7 to a 1000 ohm resistor then to the base of a 2N2222
transistor, the Emitter will go to ground and the collector to your Relay coil and then to Supply V+
A Green Led can go from the Q7 to ground which will light when the correct code is entered, as for the red led…that may be difficult as there is no trigger for the wrong code, you just have to keep pushing buttons until you get the correct sequence., I suppose you could expand on the circuit to include that feature…but I don’t have the time just this minute.
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