Password electronic lock control circuit

Circuit working principle: The unlocking signal of the combination lock consists of a series of wide pulses and narrow pulses
. IC,. , IC ib forms a bistable flip-flop; ICZo and IC2b are CC7556 dual time base
integrated circuits, forming two sets of monostable circuits; IC3 is a CC4015 dual four-bit serial shift
register , and the two sets of registers are expanded in series in the circuit into an eight-bit shift register.
The output terminals QIA-Q4A, QIB~Q4B of CC4015 respectively control the base of the transistor VT through the F3-Fio of the inverter CC4069
, the single-pole double-throw switch S, one s8 and the diode VD, one VDs.
Only all VD and one VD8 When the resistor is at a high potential, VT is turned on, causing
the relay K to close, the electromagnet D to be energized, and the lock to open; on the contrary, as long as the
cathode of VD, ~ VD8 has a low potential, the VT base is at a low level, and VT As a result, K cannot
pull in. Switch S. One Sa can directly or invert the output signal of the IC
to the base of the transistor VT to set the unlocking password of the electronic lock. The unlocking password for this circuit is
"1010110".