Practical Household Automatic Water Supply: Traditional Chinese Circui

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Household automatic water dispenserUrban water supply is relatively tight no matter what season it is, which brings great inconvenience to people's lives. The household automatic water supply introduced in this article only needs to be turned on before going to work or before going to bed at night. When the water comes, it will automatically fill the water container, automatically stop the water supply, and sound an alarm. There is no need to worry about not receiving water or water overflowing all over the floor.1． How the circuit worksThe circuit of a household automatic water supply device is shown in Figure 57. It is composed of a power transformer, water level detection and control, and alarm sound circuits. alt="57-1.jpg (36596 Byte)">Figure 57-1In the figure, transformer B, diodes D1~D4, capacitors C1, C2, zener diode DW and resistor R1 form a power circuit; gate 1 and gate 2 of IC, transistors BG1, BG2 and relay J form a water level detection and control circuit; gate 3 and gate 4 of IC1, resistors R9, R10, C9 and a speaker form an alarm sounding circuit.When the water level probes 1, 2, and 3 are not in contact with the water surface, the input terminals ⑧ and ⑨, (12) and (13) of the IC are all at low level, and the output terminal is at high level, causing the transistors BG1 and BG2 to conduct. The relay J is electrically closed, and its normally open contact J1 is closed. The solenoid valve is powered on, the faucet is opened, and the water is waiting for the arrival and filling of the water container. When water comes in and the water level in the water container rises to a certain set height, probes 1 and 3 are connected through the water medium, then the input terminal (12) and ⑤ pin of door 1 are high level, and its output end turns to low level, causing BG2 to cut off, relay J is released, the solenoid valve is closed due to power failure, and the water supply is stopped.When BG2 is turned off, its collector potential rises. This voltage passes through resistor R4 to light up the light-emitting diode LED, informing people that the water is full; the other path is added to the input terminal ⑥ of gate 4 through resistor R8, causing the audio oscillator composed of gate 3, gate 4, R9, R10, and C9 to start oscillating. The oscillation frequency is about 1000Hz. The audio signal is amplified by transistor BG3, and an alarm sound is emitted from the speaker. The sound can wake people up to turn off the power supply of the water supply, and at the same time, it also serves as a notification that the water is full. If no alarm is needed, switch K2 can be turned off.The reason why BG1 and BG2 are used in series in the circuit is to ensure that the water supply device works reliably. For example, when door 1 or BG2 fails, that is, the water cannot be stopped in time after the liquid level contacts probes 1 and 3, and the water level continues to rise. If the water surface rises to probe 2, the input end of door 2 will become high level, and its output end will turn to low level, causing BG1 to cut off, and relay J will be released to stop the water supply, thus avoiding water overflow. Therefore, when used in series, only when both pipes are saturated and conductive can the relay absorb the water supply.2. Component selection and productionB is the power transformer, which can be made of E-shaped silicon steel sheet with a core area of 10×18mm2. The primary is wound with φ0.06mm high-strength enameled wire for 5210 turns; the secondary is wound with φ0.16mm high-strength enameled wire for 400 turns.IC is an integrated circuit block, and CD4011 and other types can be selected.BG1~BG3 are all NPN transistors, 3DG12 or 9014 can be selected, β>80, BVceo≥25V, BVces≤0.5V.Dw is a voltage stabilizing diode with a voltage stabilization value of about 12V, such as 2CW5, etc.J is a DC relay, such as JZX series or JRX series, and the coil operating voltage is 12V.D1~D5 are diodes, and IN4001 can be selected.R11kΩR2, R3, R710kΩR42.5kΩR5, R6, R10, R12100kΩR8, R114．7kΩR968kΩC1, C40.01μFC2220μF25VC322μF16VY is a small diameter 0.25W, 8Ω speaker.The components of the water supply are all welded on the circuit board, and then sealed with a box to make it waterproof.The water level probe is made of thin metal and placed vertically in the water container. The water level probe can be installed integrally with the water supply and extends from the bottom of the box, or it can be installed separately and connected to the water supply by wires.The lengths of water level probes 1 and 3 are equal, and water level probe 2 is 20mm shorter than water level probes 1 and 3. The three water level probes can be placed side by side or installed in a triangle shape.The metal probe is best made of stainless steel or chrome-plated iron rod with a diameter of 4mm. The distance between probes 1 and 3 is 20mm and can be placed on the edge of the water container, as shown in Figure 57-2. …

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