Computers & Electronics

The electricity supplied to electronics

  • Last Updated:
  • May 13th, 2019 8:09 pm
[OP]
Newbie
Aug 3, 2017
65 posts
14 upvotes

The electricity supplied to electronics

I apologize if this is not the right place but I don’t know where else to ask this. I was hoping someone can help me with a quick electric/electronic lesson as my knowledge base is more academic rather than practical.
I have an electronic device that has an external transformer for a power source (i.e. a power block). If it’s relevant the electronic device is a cordless phone. One day the phone died. I determined the phone itself was fine, it was the power adaptor that died. I used another power adaptor that was close which leads to my question. The original power adaptor was 9V 800mAmps. The replacement is 9V 1000mAmps. The phone is working now but will this damage the phone over time? Is the device smart enough to only accept what it needs despite the amperage supplied? If it was 9V 2000mAmps, would that be bad?
Also what about the voltage? Had I used a 12V or 18V power adaptor would that fry the electronic device, is the device smart enough to use 9V of potential even though 12V is supplied.
Thank you
13 replies
Sr. Member
Sep 13, 2011
959 posts
609 upvotes
Québec
Your 9 volt replacement could be ok, if the polarity (the ring being positive or negative ) is he same. Don't use a overvoltage DC adapter.
Deal Guru
User avatar
Jan 9, 2011
10038 posts
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Vancouver
daydreamer7 wrote: 9V 800mAmps
9V 1000mAmps
9V 2000mAmps
9 Volts is 9 Volts. The amperage used by any given voltage is determined by the load (the electric resistance of the device being powered). The amperage shown on the power supply is what it will draw if it is connected to the device it was designed to be used with. It's fine to use your 9V 800mA device with a 9V power supply that says 1,000 mA or 2,000mA or greater, since they are designed to be used with a device that draws more current. They're not going to "push" more current into your device. What you do need to watch out for is one that is designed to draw *less* current than what you intend to use it for. Your device itself will be fine, but it will draw more current out of the power supply than what it may have been designed to supply, so the power supply could overheat.
Also what about the voltage? Had I used a 12V or 18V power adaptor would that fry the electronic device, is the device smart enough to use 9V of potential even though 12V is supplied.
Thank you
No. Never supply more voltage do a device than what it is designed to use. That will overpower, possibly overheat, and possibly damage your device.
Last edited by Kiraly on May 11th, 2019 4:38 pm, edited 3 times in total.
[OP]
Newbie
Aug 3, 2017
65 posts
14 upvotes
elgros4 wrote: Your 9 volt replacement could be ok, if the polarity (the ring being positive or negative ) is he same. Don't use a overvoltage DC adapter.
It is an AC/DC adapter. The polarity diagram are the same (positive polarity). So are you saying as long as the voltage is the same the amperage can be flexible? The device would be fine had I used a 2000mAmp adapter?
Thanks
[OP]
Newbie
Aug 3, 2017
65 posts
14 upvotes
Kiraly wrote: It's fine to use your 9V 800mA device with a 9V power supply that says 1,000 mA or 2,000mA or greater, since they are designed to be used with a device that draws more current. They're not going to "push" more current into your device. What you do need to watch out for is one that is designed to draw *less* current than what you intend to use it for. Your device itself will be fine, but it will draw more current out of the power supply than what it may have been designed to supply, so the power supply could overheat.

AAAhhh Thank you.
I was pretty sure using more volts would be problematic, wasn't sure about the amps (I needed another opinion). This is the stuff they should teach in school. Then again to be fair maybe they did I was playing hookie. On the other hand who needs school when you have RFD Face With Tears Of Joy
Thank you all.
Deal Fanatic
Aug 29, 2011
6065 posts
3145 upvotes
Mississauga
Amperage would only be an issue if the device draws more current than the power brick can supply. But in OP’s case, the replacement brick is more than capable.

Key things are supply voltage and polarity.
Deal Addict
Feb 4, 2018
1009 posts
48 upvotes
Also keep in mind some cheap adapters lie about the voltage. I've tested this with a voltmeter before, where an adapted might say its 9v, but in reality it's, let's say, 10.2v or something similar.

You'll never notice it until a few months down the line your device dies unexpectedly.
Deal Addict
Nov 12, 2006
1928 posts
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London
Poutsounia wrote: Also keep in mind some cheap adapters lie about the voltage. I've tested this with a voltmeter before, where an adapted might say its 9v, but in reality it's, let's say, 10.2v or something similar.
Those adapters typically use a very simple form of voltage regulation.
At the current they were designed to be used for, they probably are close to 9V (your example).
Measured without load, it likely is higher (such as 10.2 in your example)

The previous posts are basically correct that an adapter of the same voltage is OK, but there can be the issue above.
If it is rated for a higher current, it may require a higher load to drop the no-load voltage to what is marked on it.
It isn't quite a "lie", but you have to understand the conditions that exist when that number is determined.
If the adapter used a better form of voltage regulation, and "outputted" what is written on it under wider variations of load, there wouldn't be an issue.

My "gut" says what the OP plans will be OK, because even IF the 1A adapter has a slightly higher voltage with the load of the phone, there probably is some regulation internally.
Sr. Member
Oct 1, 2009
537 posts
234 upvotes
West coast
It should be fine. The device will take it only what it needs. The new adapter just says it's capable of producing up to 1000mA and the other one is only capable of producing up to 900mA. As someone mentioned, the polarity is the important factor as well as ensuring the plug fits.
Deal Guru
User avatar
Nov 21, 2002
10183 posts
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Winnipeg
volts have to match. wrong volts fries the device.

the amps have to match or could be greater.

But do not use lower amps. That will stress and fry the power brick/psu.
Deal Fanatic
Nov 17, 2004
7092 posts
1425 upvotes
Toronto
No such thing as too many amps, as long as the voltage matches then you are golden.
I workout to get big so I can pickup bricks and ****.
Deal Addict
Jan 21, 2018
4324 posts
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Vancouver
Poutsounia wrote: Also keep in mind some cheap adapters lie about the voltage. I've tested this with a voltmeter before, where an adapted might say its 9v, but in reality it's, let's say, 10.2v or something similar.
Unless it is a regulated DC power supply, the output voltage supplied by a cheap AC/DC adapter will be approximate and depend on the load. With no load it will read higher than the intended voltage, and with a high load (i.e., lower resistance load) it will read lower than the intended voltage. This is because the impedance of the transformer output coil is in series in the circuit with the output load, and the voltage divides between them in proportion to their relative resistance. Adapters are generally selected to provide approximately the correct voltage for their intended device load, so it's good to use one with approximately the same output amperage rating. If you use a generic 9v adapter with a variety of device loads, it wouldn't be uncommon to see the voltage range vary anywhere between 8-11 volts. But electronic devices are generally tolerant of that kind of voltage range. I've never seen a device damaged by using an AC/DC adapter of the correct voltage rating, even if the load capacity was very mismatched to the device and the device wouldn't work because the adapter couldn't supply enough current.
Deal Guru
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Nov 21, 2002
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Winnipeg
Scote64 wrote: Unless it is a regulated DC power supply, the output voltage supplied by a cheap AC/DC adapter will be approximate and depend on the load. With no load it will read higher than the intended voltage, and with a high load (i.e., lower resistance load) it will read lower than the intended voltage. This is because the impedance of the transformer output coil is in series in the circuit with the output load, and the voltage divides between them in proportion to their relative resistance. Adapters are generally selected to provide approximately the correct voltage for their intended device load, so it's good to use one with approximately the same output amperage rating. If you use a generic 9v adapter with a variety of device loads, it wouldn't be uncommon to see the voltage range vary anywhere between 8-11 volts. But electronic devices are generally tolerant of that kind of voltage range. I've never seen a device damaged by using an AC/DC adapter of the correct voltage rating, even if the load capacity was very mismatched to the device and the device wouldn't work because the adapter couldn't supply enough current.
fried a 12v device one time because The bricks were identical and didn't have my glasses. smoked pillowed out burned dead right before my eyes because wrong voltage. Took it apart and it was scorched.

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