In the apartment the phone rang. And here in the dark hallway groping you find the light switch and only then open the door. About the same you make, entering the house. Is it possible to turn on the lighting automatically, say, simultaneously with a call or when opening the door? It turns out that, installing in the hallway a simple electric device.
If you press the bell button (Fig. 1) at the front door, it will immediately trigger the relay K1, which is its contact system K1.1 will close the electric circuit of the lamp of H1, located in the hallway. And in series in the circuit can include a diode for VI receiving an incomplete ("duty") lighting.
Fig. 1
Once the call button is released, the capacitor C1 is gradually discharged through the relay coil K1, holding up to 30 with its opposite. This time is usually enough to reach the light switch S2 set in hallway.
The second device (Fig. 2) allows, in addition, turn on lights when you open the door when you returned home. The limit switch S3 is built-in the door jamb. When it's open, relay R1 and the capacitor C1 is charged. If you plan to stay in the hallway, press the light switch. Otherwise, after 30 seconds after you close the door, the light in the hallway goes off.
Fig. 2
In the third device is equipped with double-pole switch S2 that allows you to translate the lamp from normal mode to "standby". The switch S2 is in the room. If its close, when you open the door "tip" S4 will cause actuation of relay K1, which is its contact system K1.1 blocks S4 and at the same time includes call B1, warning that the door is open.
Fig. 3
All devices applied relay RAN (passport PX.564.510 P), S1 - United in parallel, the capacitors C50-18, limit switch - BC-1.
The elements of each device is placed along with the call in a plastic case size 230x190x80 mm, installed in the hallway above the entrance door.
Author: A. Shvartsman, Vinnitsa