Electronic combination lock four

The electronic password lock introduced in this example is composed of an electronic lock special integrated circuit CH220 and related peripheral components. It can set a 6-digit password at will and can be used as a password power switch for household appliances or for door locks, file safes, etc.
Circuit Working Principle
The electronic password lock circuit consists of a timing trigger circuit, a password lock circuit, an audio alarm circuit and a control execution circuit, as shown in Figure 3-101.

The timing trigger circuit is composed of transistors Vl, V2, resistors Rl-R4, light-emitting diode VL and capacitor C.
The password lock circuit is composed of the password buttons S0-S9 and the electronic lock integrated circuit IC.
The audio alarm circuit is composed of resistor R6, thyristor VT and alarm HA.
The control execution circuit is composed of resistor embryo, transistor V3, relay K (or electronically controlled lock) and diode VD.
Pin 1 (S1 terminal), 2 pin (S2 terminal), 3 pin (S3 terminal), and 6 pin (clock terminal) of the IC are program keying input terminals, which are active at high level; S pin (OUT) is the signal output terminal, this pin is usually low level and changes to high level after the unlocking password is entered correctly (i.e. when pin 7, pin 1, pin 2, pin 3 and pin 6 are added in sequence to trigger high level); pin 7 is reset. terminal, high level is active; pin 4 is the ground terminal; pin 8 is the power terminal.
In normal times, Vl and V2 are both in the cut-off state, VL does not emit light, IC pin 5 is low level, V3 is cut-off, and the relay K does not act; at the same time, VT is also in the cut-off state, and HA does not sound.
When S8 is pressed, the capacitor C begins to charge. After the charging is completed (about l, nin), Vl and V2 are turned on, VL emits light, and pin 8 of the IC obtains working power. At this time, if S1, S6, C, and S7 and S2, the S pin of the IC will output a high level, causing V3 to conduct, K to close, and the lock to be opened. If you do not know the password and mistakenly press one of the buttons S0, S3, S5, and S9, the VT will be triggered and conduct, the HA will sound an alarm, and the lock cannot be opened.
The unlock code for this circuit is 816472. When making, you can connect the buttons according to your own requirements to get different unlocking passwords.
Adjusting the resistance of Rl or changing the capacity of C can change the time for Vl and V2 to trigger conduction after pressing the first password, thereby improving the confidentiality performance of the electronic lock.
Component selection
Rl-R6 uses 1/4W carbon film resistor or metal film resistor.
C selects an aluminum capacitor with a withstand voltage of 16V.
VD uses 1N4148 silicon switching diodes.
VL uses φ5mm high-brightness light-emitting diodes.
Vl uses S9014 silicon NPN transistor; V2 uses S9012 or C8550 silicon PNP transistor; V3 uses S8050 silicon NPN transistor.
VT selects MCRlO0-6 type thyristor.
The IC uses CH220 electronic lock integrated circuit.
S0-S9 all use micro-phone micro buttons.
K chooses 6V DC relay or electronically controlled lock.
HA uses a sounder with its own audio source.