THE TOILETIt often happens when someone from the household forgets to turn the lights off in the toilet — he may be there without the use of a lot of hours. A simple automatic device which, when necessary, turns on the light in the bathroom, and when not — turn off. The electrical circuit of such device is presented in figure 1. It contains: a low-power transformer T1, rectifier VD1 — VD4, filter capacitor C1, two limit switches SB1 and SB2 relay K1. How the device works and how it performs its functions?

When the door is closed, the limit switch SB2 is open, as the relay K1, the light in this position on the toilet does not burn.
Open the door — limit switch SB2 closes the relay K1 and the lamp illuminates.
She came into the bathroom, closing the door on the latch. This closes the second limit switch SB1, is triggered and remains closed the relay; the light will continue to burn until the limit switch is not open.
Figures 2 and 4 show a heel made of sheet tin with a thickness of 0.5 mm that presses on the limit switch SB2. Heel mounted on the door so that the partial closure of the door (which is quite often) switch razemical relay circuit. The light goes out.
Figure 3 shows the limit switch is industrial production. Its quality can be used by any such having normally closed contact. To improve the reliability of operation of the device the contact is provided with a pressure box is made of the 0.5-mm plate, and heel. Its lower part facing the heel, glued Micarta (and the PCB).
Fig. 1. A circuit diagram of a device automatically turn off lights in the toilet
Fig. 1. A circuit diagram of the device automatic switch-off of light in toilet
Fig. 2. Limit switch SB1 — espagnolette
Fig. 2. Limit switch SB1 — bolt
Fig. 3. Limit switch SB2
Fig. 3. Limit switch SB2:
1—reed relay (industrial manufacture); 2 — axle; 3 — check box (steel sheet s0,5); 4—cover plate (Micarta s3); 5 — contacts (3). 6—wire (3 PCs.)

Fig. 4. Heel (steel sheet s0,5)
Fig. 4. Heel (steel sheet s0,5):
a—scan; b—General view
Limit switch SB1, as probably already guessed reader is a bolt on. Its metal parts are connected by conductors with the circuit device. Since the voltage at the parts of the catch does not exceed 9 VDC, it is absolutely safe for humans.
Step-down transformer can take from the old cellphone — the one that was used to charge it. When using reed relays РЭС64А (724) РЭС55А or (601) the power consumption of the transformer does not exceed polwatta.
When installing the device it is necessary to observe electrical safety measures. All connect the device to the network can be carried out only when de-energized the line. As the apartments, as a rule, two independent lines, to illuminate the workplace can be a portable lamp connected to the other line.
J. PARTIN, L. MARTINA, Ekaterinburg

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