How to make a circuit break after a certain period of time?

Question

Electronics

For one project, you need to make sure that when the circuit is closed (the light comes on), after a while the light goes out. After opening and closing the circuit again, the light should turn on again and then go out. Tell me how to do this.

Answer 1

The easiest and cheapest way is to solder a conventional analog single vibrator (aka “time relay”), you can change the delay duration with a variable resistor. The light bulb can be closed either with a field key or a relay.
The “more fashionable” option is to assemble on triggers. But the same RC chain will control the time constant.
You can stick a counter - then it will be even more interesting.
You can generally complicate it - use a microcontroller (but this is justified only if you need to hang something else on it).

Answer 2

I am not strong in this matter, but the command to open the circuit (for example, using a relay) can be generated using the NE555 timer. He's cheap. Operating voltage 5V.

Answer 3

Can it do this: at one position of the switch, the capacitor is quickly charged, at the other it is discharged into a light bulb?

Answer 4

What about a p-channel FET whose gate is energized through a coil?

Answer 5

The easiest and cheapest way is to solder a conventional analog single vibrator (aka “time relay”), you can change the delay duration with a variable resistor. The light bulb can be closed either with a field key or a relay.
The “more fashionable” option is to assemble on triggers. But the same RC chain will control the time constant.
You can stick a counter - then it will be even more interesting.
You can generally complicate it - use a microcontroller (but this is justified only if you need to hang something else on it).

Answer 6

The desired device, as Eddy_Em correctly noted, is called a single vibrator. Its essence is that it generates one pulse of a given duration, regardless of how long the signal came to the input. And as a key, you can also use a triac or thyristor, as well as an optocoupler (for small loads).

Answer 7

If you need it exactly, then:
- the simplest logical element generator with quartz and a divider
- some kind of microcontroller (today the simplest in terms of labor intensity)