circuit to turn on a laptop when power is restored

Thread Starter

sved

Joined Oct 11, 2021
6
Hello, I hope very much that somebody could take the time to help me, I have a chromebook laptop that I need to be always on as long as there is power. At the moment you have to push the microswitch button for it to start after a power outage.

I suspect that a few cents worth of components will save me needing to spend hundreds of dollars on a computer that has the option to start up on power restore.

I was thinking that on power restore voltage will be supplied to the switch, and that will be a signal to send a pulse of voltage to the return side of the switch, then the computer will start. It needs to only do this once because if another signal is sent it will turn the computer off. Then it needs to reset when power is lost.

How would I go about designing this? does it sound plausable?
 

Yaakov

Joined Jan 27, 2019
3,755
Welcome to AAC.

This is not a particularly difficult circuit to make, something like a one shot based on a 555 IC would take care of the pulse you need.but I would suggest you consider operating the switch mechanically, that is, using a solenoid to literally push the switch. This will avoid the complications of modifying the laptop and the vagaries of actual circuit the switch is connected to.

An added benefit is greatly simplified replacement of the computer if needed.

There are many here with great facility in cooking up these small circuits and with any luck noe or more will emerge from the AAC woodwork to assist once you’ve started on it.
 

Thread Starter

sved

Joined Oct 11, 2021
6
hi sved,
How long do the power outages last.??

E
+++
Does your chromebook laptop have internal batteries,??
Hello, good questions, the laptop does have a very old battery, it works for an hour maybe, power outages can be up to 4 hours (a record set last year when somebody decided to climb a tower) but even longer periods can occur if a fuse is tripped, then it could up to 61 hours over a weekend, friday evening-sat-sun- monday early AM
 

Thread Starter

sved

Joined Oct 11, 2021
6
Welcome to AAC.

This is not a particularly difficult circuit to make, something like a one shot based on a 555 IC would take care of the pulse you need.but I would suggest you consider operating the switch mechanically, that is, using a solenoid to literally push the switch. This will avoid the complications of modifying the laptop and the vagaries of actual circuit the switch is connected to.

An added benefit is greatly simplified replacement of the computer if needed.

There are many here with great facility in cooking up these small circuits and with any luck noe or more will emerge from the AAC woodwork to assist once you’ve started on it.
Thanks I'll look at the IC, Mechanically operated is nice idea, I'd thought about just soldering something across the microswitch. Thinking about it, chromebooks are a little bit quirky, you need a battery installed to start the computer, if its a mechanical "push button on power restore" affair you'd need to know that the internal battery had been exhausted and the computer has turned off, otherwise if power is restored before the computer has turned off, pushing the button will turn the computer off.
 

Yaakov

Joined Jan 27, 2019
3,755
My immediate and naïve solution to the laptop power state problem is to use the +5V from a USB port on the chromebook. If voltage is present, I presume we can assume the computer is on. That signal can be used to disable the pulse it would otherwise generate when commercial power reappears.
 

Thread Starter

sved

Joined Oct 11, 2021
6
My immediate and naïve solution to the laptop power state problem is to use the +5V from a USB port on the chromebook. If voltage is present, I presume we can assume the computer is on. That signal can be used to disable the pulse it would otherwise generate when commercial power reappears.
Another good idea, I'll testing the usb port for voltage when its off,
 

Thread Starter

sved

Joined Oct 11, 2021
6
Have you checked the bios settings?
Most computers/laptops have a “wake” or power on behavior settings.
As far as i can tell, and i've had a thread up on lenovos chromebook forum for a week without a reply, there is no bios on a chromebook. So i gave up on a software/FW solution and came here :)
 

Thread Starter

sved

Joined Oct 11, 2021
6
That would be surprising.
Try googling "lenovos chromebook bios"
I've had a good poke around the internet, and not found anything that actually works.
There's no BIOS utility like on a PC and everything I've found either mixes up Lenovos PC models with the chromebook models, or is misleading or untruthful.

I had a read through that link, and its like every other article I've read, it just doesnt match reality, in this example if you follow the instructions in the first paragraph you get as far as opening the terminal, but the commands are unrecognised-It doesnt work. Not to say that it couldnt work, just that with the information that is supplied it doesnt. Then in the article if you click on the "click to see full answer" it then shows another article about restoring the "BIOS" really what its doing is its reseting the chromebook to factory settings.

I was intrigued about GBB flags, that looked promising but it doesnt look like there is an option for Default to on, on power restore"

https://mrchromebox.tech/#fwscript

The rest of the article talks about changing the boot mode, but you still have to press the power button. and it doesnt solve my problem. it's a shame as I'd love it if there was a way of doing this without modding the computer.
 
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