Hallway problem - Please help

Have you considered using a solid state relay?

If i have to, I would do that, but I had to buy them and rethink the whole system then...

Okay. Are you using an automotive relay because solid state automotive relays use the same pin configuration?

They are expensive

$20.61 US

Way too much for this

Okay

The PIR should be near the light, the light should have a return ie neutral, problem solved.

Maybe some optical isolation between the battery and the mosfet could be good. You would need another power supply but an old phone charger would do it. Anyway if you're switching low side it should not be to much of a problem.

But I'm not really familiar with working on city line power so it maybe just an stoopid idea.

@Billie Nice idea, I guess, I will do so, but you did not solve the problem correctly... I guess I will do so anyways.

@Violation I dont want to have a cable to go to the sensor. I stay with the battery.

A restaurant here as sensor mounted on light switch plate rather than switch that turns on when you enter men's restroom. Also, lever on door also unlocks when you push down to leave. Have you checked for commercial sensor light switches?

If I just bought a finished product, electronics weren't fun for me. I build these things myself to a certain grade.

@LeButch okay so as far as I know, optical isolation is important if the mosfet fails. Then it could pull the gate to a high voltage and damage the rest of the circuitry. With a battery in there this could be pretty bad. My question tho, why do you want to use a battery? You have access to the power line, just put a cheap phone charger instead of the Battery and still use the boost converter if needed. Also you wouldn't have to charge it then. Also without this strict current limitation you could use a triac for switching and later maybe add some dimming capabilities. For example time dependent, so that it's not so bright during night. Or ambient light dependent...

And just make the cable come from where to mosfet goes.

I do not have access to the power line, only to the phase wire. Neutral and ground are missing. I dont want to lay 5 meters of wire for this purpose.

Okay but then you would need to put the mosfet on highside anyway and I think that's not going to work out well.

http://everycircuit.com/circuit/5942859199676416