CN216956707U

CN216956707U - Kitchen exhaust fan power control circuit based on schmidt trigger realizes

Info

Publication number: CN216956707U
Application number: CN202220910245.8U
Authority: CN
Inventors: 李显圣; 梁伟林; 宋乐乐
Original assignee: Guangxi Vocational and Technical College
Current assignee: Guangxi Vocational and Technical College
Priority date: 2022-04-20
Filing date: 2022-04-20
Publication date: 2022-07-12
Anticipated expiration: 2032-04-20

Abstract

The utility model discloses a kitchen exhaust fan power supply control circuit based on a Schmidt trigger, and belongs to the technical field of electronics. The control circuit mainly comprises Schmidt triggers U1 and U2, a relay RL1, a triode Q1, resistors R1-R5, diodes D1 and D2, capacitors C1-C3, keys K _ ON and K _ OFF, a live wire input end L _ IN and a live wire output end L _ OUT, a zero line input end N _ IN and a zero line output end N _ OUT. The Schmitt trigger U2 forms a bistable trigger for controlling the working states of the triode Q1 and the relay RL1, and the Schmitt trigger U1 forms a monostable trigger for controlling the reset of the Schmitt trigger U1. The key K _ ON is used for starting control, and the key K _ OFF is used for closing control. When the kitchen is shut down, the exhaust fan continues to work to exhaust residual oil smoke in the kitchen, the time delay is several minutes, and the exhaust fan automatically stops working, so that the phenomenon that a user forgets to close the exhaust fan to cause power waste is avoided.

Description

Kitchen exhaust fan power control circuit based on schmidt trigger realizes

Technical Field

The utility model relates to a kitchen exhaust fan control circuit, and belongs to the technical field of electronics.

Background

The switch of the exhaust fan in the current market generally directly controls the on-off of the fan power supply, and inconvenience is brought to the life of a user. For example, after a user uses a kitchen, if the exhaust fan is directly turned off, the kitchen may have residual oil smoke, if the exhaust fan is allowed to continue to work to discharge the residual oil smoke, but after that, the user often forgets to turn off the exhaust fan, which results in power waste. To this not enough, utility model patent "a kitchen air discharge fan timing circuit based on 555" provides a technical scheme, realizes the air discharge fan with timing circuit regularly automatic shutdown. However, in this technical solution, each time the potentiometer is used, the potentiometer needs to be manually adjusted to adjust the timing time length. However, the user usually does not determine the time length of each kitchen use, so that the manual adjustment of the potentiometer to achieve timing can result in too short or too long timing, thereby affecting the use effect.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model provides a kitchen exhaust fan power supply control circuit based ON a Schmidt trigger, wherein the control circuit is provided with a power-ON key K _ ON and a power-OFF key K _ OFF, the power-ON key K _ ON is pressed once, and an exhaust fan works. When the exhaust fan works, the one-time shutdown key K _ OFF is pressed, the exhaust fan continues to work to discharge residual oil smoke in a kitchen, after a few minutes of delay, the power supply control circuit disconnects the power supply of the exhaust fan, and the exhaust fan stops working.

The adopted specific technical scheme is as follows:

a kitchen exhaust fan power supply control circuit realized based ON a Schmidt trigger comprises Schmidt triggers U1 and U2, a relay RL1, a triode Q1, resistors R1-R5, diodes D1 and D2, capacitors C1-C3, keys K _ ON and K _ OFF, a live wire input end L _ IN and a live wire output end L _ OUT, a zero wire input end N _ IN and a zero wire output end N _ OUT, wherein the input end of the Schmidt trigger U1 is connected with one end of a resistor R1, one end of the key K _ OFF and the anode of a capacitor C1, the other end of the resistor R1 is connected with +5V, the other end of the key K _ OFF is grounded with the cathode of a capacitor C1, one end of the output end resistor R2 of the Schmidt trigger U1, the other end of the resistor R2 is connected with the anode of a capacitor C2 and the anode of a diode D1, and the cathode of the capacitor C2 is grounded; the input end of the Schmitt trigger U2 is connected with the cathode of the diode D1, one end of the resistor R3, one end of the capacitor C3, one end of the key K _ ON and one end of the resistor R4, the other ends of the resistor R3 and the capacitor C3 are connected with +5V, the other ends of the key K _ ON and the resistor R4 are grounded, and the output end of the Schmitt trigger U2 is connected with one end of the resistor R5; the base electrode of the triode Q1 is connected with the other end of the resistor R5, the emitter electrode is grounded, the collector electrode is connected with the anode of the diode D2 and one end of the coil of the relay RL1, and the other end of the coil of the relay RL1 and the cathode of the diode D2 are connected with + 5V; a normally open contact of the relay RL1 is connected with a live wire input end L _ IN, a common contact is connected with a live wire output end L _ OUT, and a zero line input end N _ IN is connected with a zero line output end N _ OUT; the Schmitt triggers U1 and U2 are CD40106 chips.

The utility model has the beneficial effects that: the utility model provides a kitchen exhaust fan control circuit, which is characterized in that when a user presses a shutdown key, an exhaust fan continues to work to discharge residual oil smoke in a kitchen, after a few minutes of delay, a power supply control circuit disconnects the power supply of the exhaust fan, the exhaust fan stops working, and the problem that the user forgets to shut the exhaust fan to cause power waste is avoided.

Drawings

Fig. 1 shows an embodiment of the present invention.

Detailed Description

The utility model is further described below with reference to the accompanying drawings.

The specific circuit is shown in fig. 1, and the kitchen exhaust fan power supply control circuit based on the Schmidt trigger is characterized in that: the circuit comprises Schmidt triggers U1 and U2, a relay RL1, a triode Q1, resistors R1-R5, diodes D1 and D2, capacitors C1-C3, keys K _ ON and K _ OFF, a live wire input end L _ IN and a live wire output end L _ OUT, a zero wire input end N _ IN and a zero wire output end N _ OUT, wherein the input end of the Schmidt trigger U1 is connected with one end of a resistor R1, one end of the key K _ OFF and the anode of a capacitor C1, the other end of the resistor R1 is connected with +5V, the other end of the key K _ OFF and the cathode of the capacitor C1 are grounded, the output end of the Schmidt trigger U1 is connected with one end of a resistor R2, the other end of the resistor R2 is connected with the anode of a capacitor C2 and the anode of a diode D1, and the cathode of the capacitor C2 is grounded; the input end of the Schmitt trigger U2 is connected with the cathode of the diode D1, one end of the resistor R3, one end of the capacitor C3, one end of the key K _ ON and one end of the resistor R4, the other ends of the resistor R3 and the capacitor C3 are connected with +5V, the other ends of the key K _ ON and the resistor R4 are grounded, and the output end of the Schmitt trigger U2 is connected with one end of the resistor R5; the base electrode of the triode Q1 is connected with the other end of the resistor R5, the emitter electrode is grounded, the collector electrode is connected with the anode of the diode D2 and one end of the coil of the relay RL1, and the other end of the coil of the relay RL1 and the cathode of the diode D2 are connected with + 5V; a normally open contact of the relay RL1 is connected with a live wire input end L _ IN, a common contact is connected with a live wire output end L _ OUT, and a zero line input end N _ IN is connected with a zero line output end N _ OUT; the Schmitt triggers U1 and U2 are CD40106 chips.

When the exhaust fan is implemented, the live wire access end L _ IN is connected with the live wire of a power supply, the live wire access end L _ OUT is connected with the live wire of the exhaust fan, the zero wire access end N _ IN is connected with the zero wire of the power supply, the zero wire access end is connected with the zero wire of the exhaust fan, and the normally open switch of the relay RL1 controls the opening or closing of the exhaust fan. The key K _ ON is a power-ON key, and the key K _ OFF is a power-OFF key.

Schmitt trigger U2 and its peripheral components form a bistable trigger. The resistor R3 and the resistor R4 are connected in series to divide voltage, so that the input end of the Schmitt trigger U2 is +2.5V at ordinary times, and the output state of the Schmitt trigger U2 is maintained. When the air conditioner is electrified every time, the capacitor C3 is charged temporarily, the input end of the Schmidt trigger U2 obtains a temporary high level, the Schmidt trigger U2 outputs a low level, the triode Q1 is cut off, the relay RL1 does not attract, and the exhaust fan does not work. When the starting key K _ ON is pressed once, the input end of the Schmidt trigger U2 obtains low level triggering, the output end of the Schmidt trigger U2 is inverted into high level, the triode Q1 is conducted, the relay RL1 is attracted, and the exhaust fan obtains power supply to work.

The schmitt trigger U1 and its peripheral components form a normally low and temporarily high monostable trigger. Normally, the capacitor C1 is fully charged, the input terminal of the schmitt trigger U1 is at a high level, the output terminal is at a low level, and the diode D1 is not turned on.

When the exhaust fan works, the shutdown key K _ OFF is pressed once, the capacitor C1 is discharged, the input end of the Schmidt trigger U1 obtains low level trigger, the output end of the Schmidt trigger U1 is inverted to high level, and the monostable trigger enters a temporary steady state. In a transient state, the capacitor C1 and the capacitor C2 are charged, and since the capacitor C1 and the capacitor C2 have the same capacitance, the resistor R1 is larger than the resistor R2, so that the capacitor C2 is charged faster. After about 3 minutes, the voltage of the capacitor C2 exceeds 4V, the diode D1 is conducted, the voltage of the input end of the Schmitt trigger U2 exceeds +3.5V, the output end of the Schmitt trigger U2 is turned into low level, the triode Q1 is turned off by conduction, the relay RL1 moves the contact to be separated from the common contact, the power supply of the exhaust fan is cut off, and the exhaust fan stops working. After the exhaust fan stops working, the voltage of the capacitor C1 continues to rise, after about 1 minute, the voltage of the capacitor C1 rises to +3.5V, the input end of the Schmidt trigger U1 is triggered by high level, the output end of the Schmidt trigger U1 restores to low level, the monostable trigger restores to steady state from the transient steady state, and meanwhile, the capacitor C2 discharges to prepare for the next work.

From the time when the shutdown key K2 is pressed to the time when the exhaust fan stops working, the delay time is determined by the parameters of the resistor R2 and the capacitor C2, the longer the time constant R2C2 is, the longer the delay time is, but the time constant R1C1 is ensured to be larger than the time constant R2C 2.

Claims

1. The utility model provides a kitchen air discharge fan power control circuit based on schmidt trigger realizes which characterized by: the circuit comprises Schmidt triggers U1 and U2, a relay RL1, a triode Q1, resistors R1-R5, diodes D1 and D2, capacitors C1-C3, keys K _ ON and K _ OFF, a live wire input end L _ IN and a live wire output end L _ OUT, a zero wire input end N _ IN and a zero wire output end N _ OUT, wherein the input end of the Schmidt trigger U1 is connected with one end of a resistor R1, one end of the key K _ OFF and the anode of a capacitor C1, the other end of the resistor R1 is connected with +5V, the other end of the key K _ OFF and the cathode of the capacitor C1 are grounded, the output end of the Schmidt trigger U1 is connected with one end of a resistor R2, the other end of the resistor R2 is connected with the anode of a capacitor C2 and the anode of a diode D1, and the cathode of the capacitor C2 is grounded; the input end of the Schmitt trigger U2 is connected with the cathode of the diode D1, one end of the resistor R3, one end of the capacitor C3, one end of the key K _ ON and one end of the resistor R4, the other ends of the resistor R3 and the capacitor C3 are connected with +5V, the other ends of the key K _ ON and the resistor R4 are grounded, and the output end of the Schmitt trigger U2 is connected with one end of the resistor R5; the base electrode of the triode Q1 is connected with the other end of the resistor R5, the emitter electrode is grounded, the collector electrode is connected with the anode of the diode D2 and one end of the coil of the relay RL1, and the other end of the coil of the relay RL1 and the cathode of the diode D2 are connected with + 5V; a normally open contact of the relay RL1 is connected with a live wire input end L _ IN, a common contact is connected with a live wire output end L _ OUT, and a zero line input end N _ IN is connected with a zero line output end N _ OUT; the Schmitt triggers U1 and U2 are CD40106 chips.