Electronic password lock two

This example introduces an electronic password lock made with a CD4043RS trigger integrated circuit. It uses a 4-digit input password and can only be opened after the correct password has been entered. ,
Circuit Operation The electronic code lock circuit consists of buttons S1-S10 (where S1-S4 are valid password buttons, S5-S10 is a lock button), four RS-triggered integrated circuit ICs (Al-A4) and resistors R1.
The control execution circuit is composed of a resistor R2, a transistor V, a relay K, and a diode VD.
According to the working principle of the RS flip-flop, the set terminal (S terminal) has priority over the reset terminal (R terminal). Under the condition that the EN terminal is connected to the high level, as long as the S terminal is high, regardless of the R terminal. How to change, its output (Q terminal) outputs a high level. Only the S terminal is low level and the R terminal is high level, and the Q terminal outputs low level, as shown in Figure 3-99.

The four valid password buttons Sl-S4 of the electronic combination lock are respectively connected between the R end of the four RS flip-flops (Al-A4) and the positive power supply (+9V), and the six lock buttons 55-510 are connected to the RS. Between the 50 end of the flip-flop Al and +gV. In normal times, the S and R terminals of Al are both low, the Q terminal of A4 has no output, V is in the off state, the relay K does not operate, and the electronic lock is in the off state.
When S1 is pressed, the S end of Al becomes a high level, and the Q end outputs a low level; then S2 is pressed to make the R end of A2 become a high level, and the Q end also outputs a low level; S3, the R terminal of A3 becomes a high level, and its Q terminal outputs a low level; when S4 is pressed, the R terminal of A4 becomes a high level, and the Q terminal outputs a low level, then V is turned on, K Pull in and the electronic lock is opened.
If a vanadium is pressed in S5-S10, the 5th end of Al becomes a high level, the Q terminal outputs a high level, and the circuit is locked. At this time, pressing S1-S4 has no effect. The electronic lock can only be opened by pressing S1-S4 in order.
To reset the electronic lock, turn off the power switch SO and turn it on again to reset the RS trigger, V cutoff, and K release.
Component selection
Rl and R2 use 1/4W carbon film resistors or metal film resistors.
VD selects silicon rectifier diode of type lN4001 or 1N4007.
V selects C8550 or S8550, 3CG8550 silicon PNP transistor.
IC selects CD4043 or CC4043 type four RS flip-flop integrated circuit.
S1-S10 selects the movable (button) type button; S0 selects the ordinary power switch.
K selects 9V DC relay (control electromagnet or electric lock with normally open contact).