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I want to build a circuit for my home. The setup is as follows: I've got a circuit in my house, I can turn my lights on and off with switches from different positions. I'd like to have them switched off automatically after, say, five minutes, in case I forget them on, just like it works with staircase lamps.

It seems quite challenging to me, especially if I only limit myself to mechanical spring switches, step by step relays and timers (delay relays). Could such a circuit be possible to realize only with analogic components? Am I forced to use digital electronics?

Thanks!

Edit: clarification: at any given time, I want to be able to switch the lights on and off arbitrarily, just as I would do with my living room lights, except that I want them to turn off automatically after a given interval of time.

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  • \$\begingroup\$ Mains voltage is dangerous. Rather purchase off-the-shelf products and have them installed by an electrician. \$\endgroup\$
    – skvery
    Apr 1, 2020 at 19:35
  • \$\begingroup\$ Thank you for the suggestion. I am just wondering if it would be possible, as a thought experiment. The setup is not real. Although, this is a question which was proposed to me by an electrician. \$\endgroup\$
    – Genoma
    Apr 1, 2020 at 19:46
  • \$\begingroup\$ I think you can Google NB-IoT. \$\endgroup\$
    – skvery
    Apr 1, 2020 at 20:01

2 Answers 2

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enter image description here

Figure 1. A pneumatic time delay-off switch typically used for stairwells. This model is for the British standard wall box.

There are no electronics. You press in the plunger which closes the electrical contacts. The plunger is pushed out by a spring at a rate determined by a pneumatic bleed valve which controls the rate that air re-enters the piston. When the button is close to fully out the contacts are opened.

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 2. What you've got and what you want.

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  • \$\begingroup\$ Thank you. However I might not be specific enough. At any given time, I want to be able to switch the lights off. This, apparently to me, blocks me from turning them off arbitrarily. I am going to update my question. \$\endgroup\$
    – Genoma
    Apr 1, 2020 at 19:41
  • \$\begingroup\$ Yes, you weren't specific enough. \$\endgroup\$
    – Transistor
    Apr 1, 2020 at 19:44
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Thank you all for your suggestions.

I managed to write down the schematics for what I wanted to achieve. I used a Step Relay and a Time-Delay Relay. The solution is as follows: L1 is always switched off or on by pressing P. If it is left on, on time-out the Step Relay is switched, which resets the timer and switched the light off. The Time-Delay Relay is "ON delay".Schematics for the circuit

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