Use 8v to push 12v ?

[pomkon]

I have an air purifier power adapter that outputs 12v 1a which the light indicator wont turn on. i think the adapter is faulty.

 

I have a speaker adapter that outputs  8v 1.25a. Can i use it to test my air purifier? Is it wise to keep old adapters around, that could be useful in the future?

 

the speakers also work with usb power to dc. USB outputs 5v, why does it work on the speakers?

 

I need some electronics lessons.

[Granular]

Depends on the internals of the purifier.

Have you tried using the 8V adapter? It could be that the purifier converts whatever it gets from the adapter input to 5V or a lower voltage and uses that and the 12V supply was bundled with it just because it's what the manufacturer had on hand/could get for the least money.

Or it could be that the USB input get stepped up and applying 8V to the purifier's USB power pins would work too.

You could get a DC-DC converter to step up your 8V to 12V externally, but at that point you might as well get a 12V power supply for less/the same money.

It could also be that the purifier's power circuit connected to the 12V input is bust, not the supply itself. You can check if it's the power supply by first measuring it's output with a voltmeter/multimeter. Then again, it could be putting out the correct voltage at idle and you might need to measure the voltage under load, which is trickier.

[Windows7ge]

It depends on how the purifier works. Some electomics will run adapters that putout more power the the device needs. It also depends on if the air purifier uses a "brainbox". The power delivery depending on how that was built may not be capable of stepping down 8V as accurately as 12V to the required level of the brainbox. Now if the fan/other main components are driven directly off the DC input then it should work but it will work at 2/3rd capacity. It's also possible that some brainbox components are actually inside the power adapter. Sometimes manufacturers do this for reasons unknown. I'd recommend peaking inside the purifier before aimlessly plugging in a lower voltage. If it has a circuit board with logic components it's probably ill advised because the box might pull more amps from the PSU in an attempt to compensate and 8V @ 1.25A doesn't translate to 12V 1A meaning it could burnout the speaker psu if used for too long but again if they're directly driven it should work though it might maxout the PSU and cause it to get hot.

 

Other options include what Granular said. Use a boost converter. You won't get the full 1.25A but you'd have 12V. Unless you just randomly have one handy though it's not worth it.

[pomkon]

2 minutes ago, Windows7ge said:

It depends on how the purifier works.

the purifier does not have a input label. it reads 'power supply: 12v 1a .....'

can i just try to turn on purifier with 8v 1.25v? I want to know if it still work.

[pomkon]

8 minutes ago, Windows7ge said:

If it has a circuit board with logic components

dont most circuit boards have logic gates?

[Windows7ge]

Just now, pomkon said:

the purifier does not have a input label. it reads 'power supply: 12v 1a .....'

can i just try to turn on purifier with 8v 1.25v? I want to know if it still work.

It's just a tad bit more complicated than that. Depending on how the internals of the purifier work, yes you can. In other instances you stand to see your speaker psu melting and possibly catching fire.

 

You have to know what you're working with first.

[pomkon]

19 minutes ago, Granular said:

You could get a DC-DC converter to step up your 8V to 12V externally, but at that point you might as well get a 12V power supply for less/the same money.

i found a nas chunky adapter that outputs 12v 5.83a

[Windows7ge]

1 minute ago, pomkon said:

dont most circuit boards have logic gates?

What I mean by logic is if the purifier uses a "brain" to regulate power instead of just pulling what it needs as a load is applied like a computer fan plugged into the 12V rail of an ATX PSU. It's possible the brain will maxout the power adapter or quite possibly do the opposite. If the "brain" DOESN'T see 12V it might not power on at all. This would be a power protection feature.

[pomkon]

29 minutes ago, Granular said:

Depends on the internals of the purifier.

Have you tried using the 8V adapter? It could be that the purifier converts whatever it gets from the adapter input to 5V or a lower voltage and uses that and the 12V supply was bundled with it just because it's what the manufacturer had on hand/could get for the least money.

Or it could be that the USB input get stepped up and applying 8V to the purifier's USB power pins would work too.

You could get a DC-DC converter to step up your 8V to 12V externally, but at that point you might as well get a 12V power supply for less/the same money.

It could also be that the purifier's power circuit connected to the 12V input is bust, not the supply itself. You can check if it's the power supply by first measuring it's output with a voltmeter/multimeter. Then again, it could be putting out the correct voltage at idle and you might need to measure the voltage under load, which is trickier.

should i just try and see?