Time relay (1-11 h) for half an hour. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Clocks, timers, relays, load switches

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It will take only 30 minutes to assemble a simple and reliable time relay, which at a given moment (in the range of 1-11 hours) will turn on or off any household electrical appliance with a power of up to 0,5 kW. The device is made on the basis of a conventional mechanical alarm clock, for example, "Yantar", "Sevani", "Luch", in the plastic case of which a simple device is installed, consisting of two neon lamps TN-0,3, a pair of resistors VS-0,25 or MLT- 0,5, MP-1 microswitch, sockets for a standard plug and a fuse.

The principle of operation of the time relay is simple. The coiled flat spring of the alarm bell, unwinding, goes beyond the limits of the clock mechanism until it rests against the cup of the bell. This circumstance makes it easy to turn the alarm clock into a time relay - just remove the bell cup and install a microswitch in its place. Now the alarm clock spring, releasing the stored energy, with an external coil will not rest against the cup of the bell, but will press the "button" of the microswitch, which, in turn, will close the power circuit of the external device - a tape recorder, a radio, a lamp, an electric food warmer (a safe electric stove with a temperature of the working surface no more than 95 ).

The neon lamp V1 (Fig. 1) indicates that the device is connected to the network, and V2 indicates the presence of voltage at the sockets X2. Resistors R1, R2 limit the current through V1 and V2. S1 is a microswitch activated by the alarm spring. Fuse F1 protects the device from a possible short circuit.

The signal hand is set to the desired time, the clock and alarm are started, plug X1 is connected to the network and the load is connected. At a given moment, the clock alarm will go off, and the bell spring will close contact S1: lamp V2 will light up, and the mains voltage will be supplied to the load.

By adding the toggle switch S2 (Fig. 2), you can set two modes of operation of the device: "load on" and "load off". In the first case, it works similarly to the previous one. When switching S2, the load supply circuit is closed, and at a given time, the microswitch S1 opens it.

Rice. 1. Electrical diagram of the first version of the time relay

Rice. 2. Electrical diagram of the second version of the time relay

It is not difficult to mount the elements of the time relay in the watch case. All you need is a knife, a drill, a file, glue, pencil erasers and a file. The "marketable" appearance of the device and the reliability of its operation depend on the quality of work.

The microswitch and "neons" are attached using pencil erasers (Fig. 3). In one of them, with a sharply sharpened knife, cut a groove according to the size of the microswitch so that after its installation only a "button" looks out, and pierce holes for the wires with an awl in the workpiece.

Then fix the microswitch with the second eraser, sticking it to the side of the first one from the side of the notch. For this, BF glue, "Supercement" or similar is suitable. After it dries, cut the glued block in width and height. The latter is set depending on the distance of the outer coil of the untwisted spring to the wall of the watch case. Measure it by pre-compressing the spring by 1 - 3 turns, thereby providing the necessary force with which it will press on the "button" in the future, and glue the erasers with the microswitch to the watch case.

Rice. 3. Micro switch block

Rice. 4. Arrangement of elements of the time relay in the case of the alarm clock: 1 - neon lamp, 2 - holder, 3 - spring, 4 - microswitches, 5 - sockets, 6 - fuse.

The third eraser will go to the manufacture of the neon lamp holder. Make two holes in it 1-2 mm smaller than the diameter of the neon glass bottles and, having installed the holder in the upper part of the case, drill two more holes. In order not to damage the "plastic case, this work must be done carefully, first marking future holes with an awl; then intermediate holes are drilled with a diameter of 1 - 2,5 mm. They are brought to the desired size with a drill of the appropriate diameter or with a knife. Remove irregularities with a round file. grease the holes with glue, insert neon lamps into them and fix them on the watch case.

Lastly, install the sockets and the fuse holder by drilling the necessary holes for them in the marked places on the case (Fig. 4). Under the fuse holder in the cover or in the housing, make a groove for the mains cable with a needle file.

Switch S2 (see Fig. 2) can be placed on top of the case to the right of the standard button to turn off the alarm bell or at the bottom on the right wall of the case, opposite the sockets. However, in this case, the risk of damage to the clock's pendulum will increase.

Now start installation. Make all connections with insulated wire, carefully checking the reliability of soldering and connections.

Author: A.Kabanov

See other articles Section Clocks, timers, relays, load switches.

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