Help to build my auto disconnecting circuit.

[mariah1902]

Hi !, my name is Mariah and I am new in this forum. I have come and joined this forum with really high hope that I would get some help from you people. So I have been working for a project that I really want to finish. I want to built a circuit that automatically disconnect after a certain period of time. The time can be manually changed an set by the user. It should run by a DC battery as I want it to run even if there is no electricity. Please help me, give me an idea at least.

 

[KlausST]

Hi,

Useable informations I see
* auto disconnect
* 12V
Everything else is in best case "vague".
I even don't know what you mean with "disconnect".

So I recommend to
* decide values like "current", "time range", and so on
* draw a sketch
* give additional informations about your idea.
Like: How do you expect the user to change the time. Maybe via WiFi and a cellular phone, maybe via a pot, maybe just a switch for "short delay" and "long delay".
Do you want to physically disconnect a connection, or switch OFF with a relay, or a semiconductor.
Also: When it is disconnected ... how can it be re connected?
Is it for power saving ... or for boiling an egg ..... or for safety .... or...
Mechanical solution, analog solution, microcontroller solution....
What precision? I've already built applications where 0.1% tolerance is not accepted...and others where 10% tolerance is no problem.

Tell us your ideas.

Klaus

 

[mariah1902]

Hi Klaus, thanks a lot for taking your precious time in replying to my post. Ok I am telling you what it is for. So was thinking the other day that out phone is sometimes over charged over night and we cannot do anything at all. The battery health decreases for that. More over if we decide not to charge the phone over night we end up having no time in the morning to charge the phone before going to work. So I have decided to build a circuit which will automatically disconnect the power after 3 hours, or the time which user will select. Yes if the time can be selected by a anroid phone over wifi, that would be brilliant. Please suggest me what should I need here to build this.

 

[betwixt]

A simple relay and delay circuit will cut the power either by direct switching or by a relay.
If you want to set the delay by WiFi it gets much more complicated, you can make a timer that logs in to an existing network (your home WiFi) or you can make it work as an independent access point. If you make it work as an access point (station mode) you might have problems if our phone can only connect to one network at a time because you would have to log out of your existing WiFi and in to the new one to connect to it.

I would look at ESP8266 modules, you can buy small boards with the relay already fitted. They need a 5V DC supply to power them but they can safely switch either the AC to the phone adapter or the low voltage from the adapter to the phone. You need to do some programming but the code is very simple. Look at this for an example: **broken link removed** but note that you can change the program so it works as a programmable delay instead of a simple on/off switch.

Brian.

 

[mariah1902]

Hi Betwixt, I am really glad that you took your time to write this. Actually the module which you are suggesting me to use, would it actually do the job?, and further more, when I visited that link they said they would not ship that product in my country. What should I do now?.

 

[FvM]

It's a Chinese product, check different vendors.

 

[mariah1902]

It's a Chinese product, check different vendors.

Hi ! FvM, so it is very obvious that if ebay cannot deliver it to my country amazon would do the same thing, I am saying that are there other ways to do it without just buying a circuit?. Cant we just make it on our own?. Arent there some other ways?.

 

[ZASto]

Check on AliExpress

 

[mariah1902]

Hi zasto, I really appreciate what you did, I know about Aliexpress, they really sell cheap inexpensive products, the thing is I do not own an international card to order that from here. Is there some way so that I could do it without any such circuits or modules?

 

[betwixt]

For WiFi or Bluetooth control from a mobile phone there is no practical alternative to commercial modules. They are both very complex systems that rely on components that cannot be hand assembled.

Perhaps it would help us to know what kinds of components you can get hold of without buying from international sellers.

Brian.

 

[mariah1902]

Hi Betwix, I was hoping doing it mechanically. The plan was there would be a manual switch for disconnecting the circuit and motor would push a rod to turn the switch off. Is it possible ?