Bookcase moth-proofing circuit made with 7556 dual-time base circuit

The circuit of the bookcase mothproofing device is shown in the figure below. ICI and IC2 are CC7556 dual-time base circuits, IC1 and peripheral components form a monostable timing circuit, and IC2 and peripheral components form a multivibrator. When the power switch S is closed, the trigger terminal ⑥ of ICI gets a momentary low-level pulse, which changes the output of IC1's ⑤ pin from low level to high level. As C2 continues to charge, after about 30 minutes, IC1 resets, the monostable process ends, and ICI's ⑤ pin becomes low level again. When ICI's ⑤ pin outputs a high level, IC2's reset terminal ⑩ pin becomes a high level, and the multivibrator composed of IC2 and others begins to oscillate. The square wave pulse signal output by its ⑨ pin is amplified by the transistor VT2 power amplifier, and then boosted to 1.SkV by the boost transformer T, driving the ozone electron tube QA65 to produce ozone, which sterilizes and prevents moths on the books in the bookcase. About 30 minutes later, as pin ⑤ of IC1 becomes low level, pin ⑩ of IC2 also becomes low level, IC2 resets and stops working, its pin ⑨ outputs low level, VT2 is cut off, and QA65 stops producing ozone.

LED is used to indicate the working status of the mothproofer. When the 5th pin of IC1 outputs a high level, the transistor VT1 is turned on, the LED is lit, indicating that the mothproofer is working; when the 5th pin of IC1 outputs a low level, VT1 is turned off, the LED is turned off, indicating that the mothproofer has finished working.