We save electricity. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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We save electricity. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Lighting

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The author proposes two simple devices that automatically turn off electric lighting when it is not needed, and thus prevent unnecessary consumption of electricity.

The automatic switch "Day-night" works simply - it reacts to external illumination. If it is dark outside, the device turns on the lighting lamp, and at dawn, when the level of natural light increases, turns it off.

The scheme of the automaton is shown in fig. one.

(click to enlarge)

At the input it has a light sensor - a photodiode VD1, at the output - a triac VS1. The response threshold is adjusted by a trimming resistor R2. The R3C3 circuit provides a delay in the response to a change in sensor illumination, which is necessary to prevent the EL1 lamp from flashing when the photodiode is briefly exposed to the headlights of passing cars or lightning flashes. The use of a triac as a load switch (incandescent lamp EL1) made it possible to abandon the diode bridge, which would be required for a trinistor.

When developing this device, I had to face the problem of choosing a light sensor. The fact is that there are no photoresistors or photodiodes on sale that are designed to work in the visible part of the spectrum of light radiation. A self-made sensor from a transistor with an open case turned out to be very unreliable. It was influenced not only by illumination, but also by the ambient temperature and other factors (for example, air humidity). The best sensors turned out to be IR photodiodes FD256, FD263 and FD320 from the remote control systems of old TVs, which also confidently respond to visible light.

The power unit of the machine consists of a quenching capacitor C4, a rectifier on diodes VD3 and VD4 with a smoothing capacitor C2 and a zener diode VD2.

The timer-switch, the circuit of which is shown in fig. 2, is suitable for installation at the front door of an entrance or on the landings of a multi-storey building - wherever a manually turned on lighting device needs to be automatically turned off after a certain time.

(click to enlarge)

The device is a time relay triggered by pressing the SB1 button, which automatically turns off the light with a delay of several minutes to an hour. The required duration of the lamp is set by a trimming resistor R1. If desired, its engine can be equipped with a graduated scale. The control interval is changed by selecting the capacitor C1 and the resistor R2. The output circuits and the power supply unit of the timer do not differ from those in the Day-Night switch described above.

Although the state of the counter DD2 when the power is turned on may be arbitrary, as a result of counting the pulses generated by the multivibrator on the elements DD1.1 and DD1.2, after a while, pin 15 of the counter will be set high, and the outputs of the parallel-connected elements DD1.3, DD1.4 .1 low voltage level. As a result, the VS1 triac will be closed, the EL1 lamp will be extinguished, and the multivibrator will stop working. In this state, the device can remain indefinitely - until the SB2 button is pressed. This press will bring the counter DD15 to zero with low levels on all outputs, including pin XNUMX.

The high level set as a result of this at the outputs of the elements DD1.3, DD1.4 will open the transistor VT1, and with it the triac VS1. The EL1 lamp will be on. The multivibrator will start working, and after counting 1024 (2 to the tenth power) of its pulses, a high level will be set again at the output 15 of the counter DD2, which will turn off the lighting. The machine will wait for a new pressing of the SB1 button.

On fig. 3 shows the circuit board of the timer-switch.

We save electricity

Author: V.Bobrovsky, Nartkala, Kabardino-Balkaria

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