Power adapter question - volts? amps? What matters?

NeilF

NeilF

NeilF

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I have a video converter box (ADS Instant DVD 2.0) for which the power supply has died.
Output: 5V 2.4A

Now, I plugged in another adapter with seemingly the same spec and although it allowed me to capture the video, the audio was non-existant and instead I get horrible crackling. It's rated:-
Output: 5V 2.4A

If I plug in an adapter from a radio I have, everything works a treat but the unit gets VERY hot, and seem to freeze quite easily?:-
Output:9V 1A

So I imagine the 9V one is just pumping too many volts into the unit and it's in risk of overheating/melting?

I'll assume the first replacement PSU (5V 2.4A) is simply poor quality and that's why it's cracking?


Anyway, I can see universal adapters out there which allow 3V, 4.5V, 5V, 6V, 7.5V, 9V or 12V with a max DC power of 1500mA. If I was to get one of these, would they most likely be OK?

ie: What's important the volts or amps?
 
Amps and Volts are important.

On the one hand, too many amps is not usually a problem because a device draws what it needs. However, with most power supplys of that ilk, the voltage is regulated by the current drawn so if you are drawing less current than the rating, it will pump more volts instead.

A certain high street electronics store has what you require (5v,2.25a).
 
23JMZ07 said:
A certain high street electronics store has what you require (5v,2.25a).
Click to expand...

For about £20... On an African river similar ones (as mentioned in OP = 1.5A) for half the price...

So if amps is less important, I'll got for that one (variable volts and 1.5A) and hope for the best...
 
The adaptor needs to have equal or greater amps, voltage will want to be within +/- 5% of the original value and of course the connector needs to be the same.
 
Don't buy a power adapter rated for less current than you need! It'd be fine to use one rated for more than you need as the device will only take what it required, but buying an adapter only capable of delivering 1.5A for a unit which requires 2.4A is a recipe for overheating adapter!

The other 2.4A 5V adapter was noisy most likely because it was either poorly smoothed DC or potentially even AC. The unit you're powering may also have a requirement for a regulated adapter or be particularly sensitive to SMPS noise. A photo of the original AC adapter will help us recommend a new one :)
 
Volts = need to be exact, to much can kill your device

polarity = needs to be right usually the adapters that come with plugs to fit almost everything have reversible heads (i dont know if wrong matters much on my modem it just didnt work when the polarity was wrong)

AMPS = the device will only take what it needs so aslong as the power source gives at a minimum what the device requires its fine
 
Dr.EM said:
Don't buy a power adapter rated for less current than you need! It'd be fine to use one rated for more than you need as the device will only take what it required, but buying an adapter only capable of delivering 1.5A for a unit which requires 2.4A is a recipe for overheating adapter!

The other 2.4A 5V adapter was noisy most likely because it was either poorly smoothed DC or potentially even AC. The unit you're powering may also have a requirement for a regulated adapter or be particularly sensitive to SMPS noise. A photo of the original AC adapter will help us recommend a new one :)
Click to expand...

The model number is DVE DSA-0151A-05
Output +5V 2.4A

It has the small 2mm barrel connector head.


The replacement I got was the same model number but had a bigger head on it. I connected a smaller one in it's palce but it malfunctions (crackling audio) as described above!


The one that works, but which has 9V instead of 5V, and is only 1A, is a ukad840090-1000
 
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speaking of which, i remember something, but i cant truthly remember it all, so I am probbally wrong, but, I heard something like "Volts is not what causes Death, if the current is non exsistant" so another words, High volts and no current, the volts wont kill you, but if there is current its fatal ??
 
ShiWarrior said:
speaking of which, i remember something, but i cant truthly remember it all, so I am probbally wrong, but, I heard something like "Volts is not what causes Death, if the current is non exsistant" so another words, High volts and no current, the volts wont kill you, but if there is current its fatal ??
Click to expand...

That's why static electricity shocks don't (usually) kill you despite being in the thousands of volts. :)
 
ShiWarrior said:
speaking of which, i remember something, but i cant truthly remember it all, so I am probbally wrong, but, I heard something like "Volts is not what causes Death, if the current is non exsistant" so another words, High volts and no current, the volts wont kill you, but if there is current its fatal ??
Click to expand...

"It's volts that jolt, but mills that kill."
 
This thread makes Electrical Engineers cry :(

To the OP, Volts must be roughly equal to the old power supply, Amps must be equal or greater than. Please do pay close attention to whether the power supplies you're trying are AC or DC too.

I'm actually shocked that you didn't kill the whole thing when you plugged the 9v supply in! :eek:
 
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Somewhat true, you generally need greater than 50 volts to cause damage to a human (unless your skin is wet or you have an open wound). This is because the skin has a high resistance and needs to reach a breakdown voltage where it turns from insulating to conducting. After that it's possible for the current to pass through vital organs, such as the heart, which of course will kill you.
 
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