In order to remove the odor in the bathroom in time, many families have installed ventilation fans, but some visitors or children often forget to turn them on. In order to solve this problem, an electronic device that can automatically control the ventilator and the lighting lamp is designed, which does not add any trouble to people who go to the toilet, but also can automatically ventilate and switch on and off the lights, which is energy-saving and convenient.

principle of operation

The circuit working principle of the device is shown in Figure 1. It consists of a magnetic switch circuit, a monostable delay circuit, a lighting lamp control circuit, a ventilator control circuit and a power supply circuit. When the bathroom door is closed, the permanent magnet ZT is very close to the normally closed reed switch AG. Due to the magnetic force of ZT, the C contact in AG is open, and the transistor VT is turned off without bias current. At this time, the ② pin of the time-base integrated circuit IC 1 is at a high level, so IC 1 is in a reset state, the ③ pin of IC 1 outputs a low level, the relay J does not pull in without current, and the ventilator and the. Once someone enters the bathroom, the distance between ZT and AG will inevitably increase at the moment of entering the bathroom, so that the magnetic field lines of ZT can't act on AG, so the two contacts in AG reset contact, and the transistor is biased and turned on at this time. After VT is turned on, the ② pin of IC 1 becomes low level (only the saturated voltage drop value of VT), and the IC triggers setting. At this time, the pin ③ of IC 1 jumps from the original low level to the high level, and the relay J is electrically attracted. After J is pulled in, its normally open contact J 1- 1 is closed, and the ventilator M is electrified and starts to exhaust. At the same time, another group of normally open contacts J 1-2 of J is also closed, and the lighting lamp H is energized, and its height can be adjusted by RP. If it is daytime, due to the strong light irradiation on the photosensitive resistor CdS, the internal resistance of the CdS is very small, and the voltage across the phase-shifting capacitor C6 is not enough to turn on the trigger diode 2ST, so VS is blocked, there is no trigger current, and the illumination lamp H will not light up. At night, because there is no sunlight on CdS, the internal resistance of CdS becomes very large, which is equivalent to opening the circuit. At this time, 2ST is turned on, VS is turned on, and lighting lamp H is turned on.

After opening the door and entering the bathroom, although the door is closed again, at this time, due to the monostable effect of IC 1, the circuit is still in the state of ventilation and lighting (at night). When the door is opened, ZT will stay away from AG and then close again, which will cause ZT to approach AG again. After a delay, the lamp and ventilator will automatically stop working. In order to ensure that the door is closed at ordinary times, it is necessary to put a tension spring outside the door or replace it with a loose leaf with a torsion spring, so that the back door will automatically close and ZT and AG will be close together.

The device reduces the voltage and limits the current through capacitor C5, rectifies it through full bridge U, filters it through C4, stabilizes it through VDW, and supplies it to the DC power supply of the circuit.

Component selection and manufacturing

See the table below for a list of components.

Make up? Number? Name? Weighing? Type? Number? Count? Quantity? Make up? Number? Name? Weighing? Type? Number? Count? quantity

R 1、6？ Resist? 10K？ 2? C5？ Metallized capacitor? 0.068u？ Withstand voltage ≥400V? 1

R2？ Resist? 5. 1K？ 1? C6？ Metallized capacitor? 0. 1u/ 160V？ 1

R3*？ Resist? 1M？ 1? VD？ Rectifier diode? IN400 1？ 1

R4*？ Resist? 5 1Ω? 1? VDW？ Zener diode? 12V？ 1

R5？ Resist? 1M/ 1W？ 1? 2ST？ Bidirectional trigger diode? Turning voltage 30-40V? 1

RP？ Potentiometer? 100K？ Linear? 1? VT？ Transistor? 90 14? 1

CD? Photosensitive resistor? MG45-32 and other unsealed types? 1? VS？ Bidirectional thyristor? 3A/400V？ 1

C 1、3？ Polyester capacitor? 0.0 1u？ 2? IC？ Time base integrated circuit? NE555？ 1

C2？ Electrolytic capacitor? 47u？ 1? j？ Electromagnetic relay? JRX- 13F？ 1

C4？ Electrolytic capacitor? 100uF/50V？ 1? AG？ Reed switch? φ 4 mm normally closed type? 1

The monostable working time of IC is determined by the value of 1. 1R3C2. Adjusting RP can change the brightness of lighting lamp H, and RP can choose potentiometer or solid variable resistor. When it is found that relay J cannot attract, the resistance of R4 can be reduced or simply omitted. After the whole circuit is qualified in welding and debugging, it can be put into a plastic box and put into use.