Automatic staircase lighting control. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Lighting

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With the help of this machine, the light turns on when a person appears on the staircase and turns off after he leaves. The use of the machine saves at least 1,7 megawatt-hours of electricity per year at one entrance of a five-story building. Savings are achieved due to the fact that at night the lighting is turned off, because. no one walks on the stairs at this time. In addition, the service life of electric bulbs is increased due to the lengthening of the front of the on-off pulses, as well as feeding them only with positive half-cycles of the mains voltage.

The machine responds to changes in background noise in the service area. Sensitive elements are acoustic sensors that "feel" a person at a distance of 7 - 8 m (Fig. 1).

The sensor consists of a microphone (piezo emitter ZP-3) and a preamplifier based on transistors VT1 - VT3. Each of the two sensors is connected to its own processing channel (Fig. 2).

Fig.2 (click to enlarge)

Here the signal is filtered (the notch filter on DA1.1 suppresses interference at a frequency of 50 Hz to a level of 50 dB) and is amplified by the operational amplifier DA1.2

The output of the first channel is connected to the inverting input of the DA2 comparator, and the output of the second channel is connected to the non-inverting input. Thus, noise signals with the same amplitude and phase at the outputs of both channels are not recorded by the DA2 comparator. Exceeding the signal in one of the channels leads to the appearance of the log level. "1" at the output 9 of the trigger DD1.1, while the generator starts on DD3.1, DD3.2, VT4 and the counter DD2 starts counting pulses. At the same time, the log "0" at pin 8 DD1.1 sets output 0 DD6 to "1.2", the transistor VT5 closes, opening the thyristor VD2, which turns on the lighting.

When the counter DD2 counts 64 pulse periods of the generator DD3.1, DD3.2, the light will turn off.

With the indicated values, the pulse period of the generator DD3.1, DD3.2 can be changed by resistor R23 from fractions to tens of seconds. On the elements DD3.3, DD3.4, the node for the initial reset of the machine when the power is turned on is assembled.

The device is powered by any stabilized source that provides Upit.=5 V at a current of 0,3 A and a ripple voltage of 20 mV.

The design and installation can be arbitrary, but the following must be taken into account. The sensors should be enclosed in metal screens, the front side is closed with a metal mesh. The signal wire from the sensors to the main unit must be shielded. The sensors are mounted on the walls of the staircase through gaskets that absorb mechanical vibrations. They once interfere at a distance from each other equal to twice the distance from each of them to the floor or ceiling of the entrance, i.e. are placed evenly along the height of the house, and hence the staircase. It is desirable to place the main unit in a metal case, the VD2 thyristor - on a radiator with an area of ​​10 square meters. cm, isolated from the body.

The proposed device in the strict sense is not an automaton, because involves "manual" switching off in the morning and in the evening of the mains supply, for which you can use the light switch available in the entrance. However, this "disadvantage" can be eliminated if the device is supplemented with any of the known photorelay circuits.

The setting of the machine is as follows. By selecting resistor R4, Ucont.=2,4 V is set at the output of each of the sensors. Resistor R7 achieves maximum frequency suppression of 50 Hz by notch filters for each channel. Resistor R14 at pin 7 of DA2 sets the level of logic "0", and then slightly move the slider R14 in the opposite direction until the logical "2" is set at the output of DA1. Resistor R11 sets the required sensitivity of the channels, and R23 - the desired glow time of the bulbs after the arrival of the exciting signal.

In addition to stairwells, the machine can be used to control the lighting of collective basements, garages, etc.

See other articles Section Lighting.

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