It often happens when someone from the household forgets to turn off a the light in the toilet - it can burn there without the use of a lot of hours. Offered simple automatic device that, when necessary, turns on the light in the toilet, and when not - off. Electric diagram of such a device presented in figure 1. It contains: a low-power transformer T1. rectifier VD1 - VD4, filter capacitor C1, two limit switches SB1 and SB2, the relay K1. How the device works and how it performs its functions?
With the door closed limit switch SB2 is open, and the relay K1, the light in this position is in the toilet is not lit.
Open the door limit switch SB2 closes relay K1 and the lamp lights up.
Came into the bathroom, closed the door on the latch. This closes the second limit switch SB1 is triggered and remains closed relays; light will continue to burn until the limit switch opens.
Figures 2 and 4 show the heel, made of sheet steel thickness 0.5 mm which depresses limit switch SB2. The heel is fixed to the door so to the incomplete closure of the door (which is pretty often) switch rozmital circuit of the relay. The light will go out.
Figure 3 shows the limit switches industrial production. In his the quality can be any such, having a normally closed contact. To improve the reliability of operation of the device the contact is provided with a push-top the box is made of the same 0,5 mm tinplate, and heel. To the bottom, facing the heel, glued-plated hardened paper (and the PCB).
Fig. 1. A circuit diagram of an automatic shut-off device light in the toilet
Fig. 2. Limit switch SB1 - latch
IP. 3. Limit switch SB2: 1-reed (industrial manufacture); 2 - axle; 3 - box (steel sheet s0,5); 4-trim (s3-plated hardened paper); 5 - contacts (3 PCs); 6-wire (3 PCs.)
Fig. 4. Heel (steel sheet s0,5): a-scan; b-General view
Limit switch SB1, as already guessed by the reader, is the latch. Its metal parts are connected by conductors with the circuit device. Since the voltage on the parts of the latch is less than 9 VDC, it is perfectly safe for humans.
Step-down transformer can be rented from your old mobile phone - the which was used to charge it. When using reed relays RASA (724) or RECA (601) power transformer and will not exceed half-watt.
When mounting the device, you must comply with electrical safety measures. All connect the device to the network can only be made when de-energized the line. As in the apartments, as a rule, two independent lines, it is possible to illuminate the working place a portable lamp that is connected to the other line.
Authors: J. Martin, L. Martina, Ekaterinburg