Automatic water supply device for washing hands. Encyclopedia of radio electronics and electrical engineering

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To save the resources of the planet and your own budget, you can make a simple device that will reduce the consumption of water, electricity, fuel during such a mundane operation as washing hands, rinsing dishes in running water. It can be mounted both indoors and outdoors on a personal plot, in a household yard, in a public place. The device, when necessary, automatically supplies water for a few seconds. For example, if it takes two minutes to wash your hands, then the faucet usually runs all the time. With an automatic water supply device, it can be reduced to 15 ... 30 s.

The scheme of the proposed device is shown in fig. 1. As a basis, a ready-made industrial control unit from a thermal hand dryer - an "electric towel" was used, many have met with similar devices in public places. The scheme was compiled on a printed circuit board, the numbering of elements is conditional, since there were no positional designations on the board. When transforming the device from a "dryer" to a "sprinkler", minor changes and improvements were made to it. Since the control unit does not contain any unique parts, it is not difficult to make a similar design yourself without using a ready-made factory-made module.

Rice. 1. Diagram of the device (click to enlarge)

AC mains voltage 230 V is supplied to the load connected to the output of the device through a fusible link FU1, closed contacts of the switch SB1 and an open triac VS1. The load of the latter is two electromagnetic inlet valves K1, K2, an incandescent lamp EL1 and a resistor R7. In the absence of voltage at the winding terminals, the solenoid valves shut off the supply of cold and hot water. The incandescent lamp is designed to illuminate the sink. Varistor RU1 reduces the likelihood of damage to the windings of solenoid valves by high voltage due to self-induction voltage surges when the power is turned off.

On the photodiode VD1 and the emitting IR diode VD2, a proximity sensor is assembled, working on reflection. On the logical element DD1.2 and the elements R12, R15, C4, VD3, a generator of short pulses is made, following at a frequency of approximately 145 Hz with a duty cycle of about 10. When the output of DD1.2 (pin 4) is log. 0, the transistor VT3 is open, current flows through the radiating diode VD2. When a light pulse from VD1, reflected, for example, from hands, hits the photodiode VD2, the transistors VT1, VT2 open for a short time, and if at the same time there is a log on pins 1 and 2 of the DD1.1 element. 1, then its output (pin 3) will have a low voltage. That is, the operation of the photo relay is synchronized with the operation of the generator on DD1.2, which improves the noise immunity of the photo sensor.

At log. 0 at the output DD1.1 through the current-limiting resistor R11 and the diode VD4 the capacitor C5 is charged. The log level appears at the output of the DD1.3 element. 1. Next, capacitor C18 is charged through R9 and VD9, a log appears at the output of DD1.4. 0, and transistor VT4 opens. Together with it, the phototriac of the optocoupler U1 opens, and then the powerful high-voltage triac VS1. As a result, the windings of the solenoid valves K1, K2 are supplied with a mains voltage of 230 V, which unblocks the water supply. The time during which it will flow after the reflected IR pulses disappear at the input of the photosensor depends on the parameters of the R20C9 time-setting circuit (at the values ​​\u7b\uXNUMXbspecified in the diagram - about XNUMX s).

When the device is connected to the network, the HL1 LED shines in a weak green color, and during the time when the supply voltage is supplied to the load, it is bright yellow. The C3R4 circuit for modern triacs is not required, and if you do not plan to install an EL1 incandescent lamp, then it should be turned off altogether. Inductor L1 slightly reduces possible interference from the operation of the triac current switch, and also, like the C3R4 circuit, reduces the likelihood of opening the triac VS1 due to impulse noise in the power supply. If there is such a problem, a conventional LC filter can be mounted at the power input of the device.

Compared to the original version, the following changes have been made to the device:

- additionally introduced varistor RU1, resistors R8, R19, LED HL1, inductor L1;
- instead of R4 with a nominal resistance of 56 ohms and a dissipation power of 0,125 W, a resistor with a nominal value of 180 ohms and a dissipation power of 1 W is installed;
- resistor R9 (56 Ohm, 0,125 W) is replaced by a resistor with a nominal value of 68 Ohm (0,5 W);
- resistors R6, R10 and R20 (with nominal resistance of 620 Ohm, 10 and 470 kOhm, respectively) were replaced by resistors with the same dissipation power and ratings of 470 Ohm, 3,3 kOhm and 2,2 MOhm;
- instead of capacitors C7 (220 uF) and C9 (1 uF), capacitors with a capacity of 1000 and 4,7 uF, respectively, are installed.

Most of the parts are mounted on a printed circuit board made of one-sided foil fiberglass (Fig. 2). The view of the circuit board from the installation side of the parts is shown in fig. 3. As water solenoid valves K1, K2, single valves for automatic washing machines or similar free-closed valves designed for AC 230V control can be used. It is advisable to provide for redundancy - in this case, each branch of the water supply must be blocked by two valves, through which water passes in series. Do not use corrugated hoses to connect valves to the water supply system - they will crack. Thick rubber ones will do. Mixer, manual control and shut-off valves must be connected to the earth circuit.

Rice. 2. PCB

Rice. 3. Circuit board

It is unacceptable to use the "zero" wire as the last one.

Resistors R4, R9, R17 are imported non-flammable, domestic R1-7 or wire ones in a ceramic case are also suitable. The remaining resistors are MLT, OMLT, RPM, S1-4, S2-14, S2-23 or analogues with the corresponding dissipation power. Vari-torus RU1 - domestic disk CH2-1A for classification voltage 560 V, it can be replaced by imported FNR-10K561, FNR-14K561, INR14D561, ENC561 or other similar ones. Capacitors C2, C3, C6 - with a rated voltage of alternating current 275 V or direct current of at least 630 V. Oxide capacitors - K50-68, K53-14, K53-19 or analogues.

Instead of diodes 1 N4148, any of 1SS176S, 1SS244, 1N914, KD510A and KD521, KD522 series are suitable. Rectifier diodes 1 N4007 are replaceable by any of 1N4001 - 1N4006, UF4001 -UF4007, KD209, KD243, KD247 series, Zener diode 1 N5349 - P6KE12A, 1PMT5927BT3.

Replacing the HEF4093BP chip - CD4093A, CD4093B, K561TL1, KR1561TL1. Instead of KTC9012 transistors, you can use any of the SS9012, 2SA1150, 2SB1116, KT6115 series (in place of VT3 it is desirable to install an instance with the highest possible base current transfer coefficient). The MOC3021 low-power optocoupler can be replaced by any of the S21ME3, S21ME3F, S21ME4, S21ME4F series (same pinout). Triac BTB12-600C (installed on a ribbed duralumin heat sink with a cooling surface area of ​​about 8 cm²) can be replaced by 2N6344, MAC8M, MAC8N, MAC15N, MAC218A6FP, MAC320, BTA10-600C, BTA08-600SW, BTB06-600BW. Since there is no forced air cooling in this design, the maximum load power of the triac should not exceed 300 watts.

The L-59GYW bi-color yellow/green LED can be replaced with any similar common cathode LED or two conventional continuous LEDs without built-in resistors. Installed in a convertible design, the IR emitting diode VD2 and the photodiode VD1 are of unknown brands. When manufacturing a device from scratch, any imported emitting diode from a faulty or unnecessary remote control can be used as the first one, and any IR photodiode with a lens with a diameter of 5 mm in black or dark red can be used as the second one.

To increase sensitivity, instead of a photodiode, a silicon IR phototransistor with a dark lens, such as L610MP4BT/BD, can be installed. Similar phototransistors can be found in old VCRs, full size VHS camcorders, and old floppy disk readers. If the photo sensor is placed at a distance from the circuit board, then the photo transistor is connected with an insulated shielded wire.

Fuse holder FU1 - DVP-4, DVP-7. Power switch - any with two groups of contacts, designed for switching current of at least 4 A at a mains voltage of 250 V, for example, PKN-41-1-2, KDC-A04, ESB99902S. Inductor L1 is a U-shaped wire jumper, on which two ferrite tubes 15 ... 25 mm long or an W-shaped ferrite magnetic core with dimensions 6x8x2 mm are put on.

Unmistakably made from serviceable parts, the device starts working immediately after being plugged into the network. With a standard photodiode and resistors R1, R2 with the ratings indicated on the diagram, the device responds to pulses of an emitting IR diode reflected from the palm from a distance of about 35 cm. With a phototransistor, the sensitivity will be higher. By replacing R20 with a resistor of greater or lesser resistance, the exposure time can be increased or decreased accordingly.

All structural elements are galvanically connected to the 230 V AC network, therefore they must be reliably protected from water ingress. To pre-configure the device, instead of connecting it to the network, you can use a laboratory power supply with an output voltage of 18 V DC (for example, one of those described in [1, 2]), connecting its output through a 150 Ohm (1 W) resistor, observing the polarity to the conclusions of the zener diode VD10. The operation of the device in this case can be controlled by changing the color of the glow of the HL1 LED. From this design, you can make a successful symbiosis with the device [3], operating them together.

Literature

1. Butov A. Laboratory power supply with self-resetting fuse protection. - Radio, 2005, No. 10, p. 54-57.
2. Butov A. Switching laboratory power supply on the LM2575T-Adj. - Radio, 2010, No. 3, p. 23, 24.
3. Butov A. High humidity alarm. - Radio, 2015, No. 1, p. 49-51.

Author: A. Pakhomov

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