central heating circuit

When heating comes on, the thermal control circuit first flips over, the delay circuit is cleared, and starts timing to
output low voltage. The strobe pin of the controller TWH8751 is low , so the output is controlled by pin ①. Because the indoor temperature is low, the temperature control circuit outputs
a high potential and controls TWH8751 to open the valve and heat up the room. If there is no one in the room within half an hour, the count ends. CD4060
outputs high potential (well self-locking). The strobe terminal is at high potential and turns off the gas automatically. If someone comes within a certain period of time, the voice control circuit outputs a positive voltage
, clears the CD4060, and outputs a low potential. Because there are people in the room, there are often sounds, such as conversations, coughs, footsteps,
bench sounds, etc., so that the CD4060 is often cleared and maintains a low-level output. At this time, the controller is controlled by the low- level to maintain a constant temperature in the room.
If the sound continues within half an hour, a gas shut-off forecast (acoustic and visual alarm signal) will be issued at a certain period before the gas shut-off. Since
the sound emitted by the piezoelectric ceramic chip is very slight, it will not trigger the sound circuit and cause loss of control. When people in the room (if there are people) see or hear the sound
and light signals, they can cough or make other sounds, and the counting circuit will reach zero and start timing again. If the person leaves the room,
the valve will automatically close after half an hour.
    Each part of the system circuit requires a DC voltage of 6V, and the output DC voltage of the DC stabilized power supply we designed is 12V.
Therefore, the resistor RGZ mainly plays the role of current limiting and voltage reduction. At the same time, two 3V Zener diodes are also used in the temperature control circuit for voltage stabilization to
ensure the stability of the power supply; VD51 plays a locking role in the delay circuit. When the ③ pin of CD4060 D outputs high level, it is turned on. The oscillator stops vibrating and keeps the high level of pin ③ unchanged. The diodes VD52 and VD53 are used to prevent the mutual influence between the
sound control circuit and the thermal control circuit .