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AC adapter help!

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transalinn

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My guitar effect needs 9V, 300mA and 'centre minus' plug adapter.
But my adapter is 9.6V, 200mA and a symbol like that (+....0....-).
Also it is not the same brand with my guitar effect.
Can I use that 200mA adapter at 300mA equipment ?? Also volt is different.
 
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No. You need an adaptor rated at 9 volts and at least 300 ma. Something bad will happen if you try to use the 200 ma unit.
 
The best thing to do is to check it with a meter.

Make sure the center pin has the black lead from the meter (in your case) and the display shows the correct voltage and no "-" to the left of the voltage reading.

Most transformers will have a C for the outer shield and a DOT in the center of the C for the center pin.

The DOT should have a "-" and the outer "C" should have a "+".

Hope this helps.
 
They only thing bad that will happen is you'll get distortion at a lower volume setting or higher signal level. .6 volts over the nominal called for better not blow the circuit or it wasn't made properly. Although you should follow mramos1's instructions to determine if the polarity is okay. If it's wrong, it's only a matter of resoldering the cable.
 
If the circuit has a very low current (it probably does) then a 9V/300mA adapter could have a 12V output and a 9.6V/200ma adapter could have a 16V output. I would use the bigger one because its voltage won't be so high.
 
thanks to all your advice.
i'll buy 9v/300mA :)
btw, i also read in some thread that same volt (9) with higher mA (more than 300) can use for my equipment. is that true?
thanks!
 
Yes, and it will run cooler.
 
The circuit takes only as much supply current as it needs.

A 100mA adapter is crap.
A 200mA adapter without a load might double its voltage.
A 300mA adapter without a load might have a voltage that is 1.5 times its full load voltage.
A 500mA adapter without a load might have a voltage only 1.2 times its full load voltage.
 
That's true adaptors generally get better as output current increases.

You can buy multipurpose adaptors that have several voltage settings and reversible polarity; I would recommend one for this application.
 
Thanks so much

Thanks to all your help!
so how about voltage ?
more voltage is better like Ampere?
sorry to say beginner question.
 
A supply voltage that is too high destroys electronic circuits.

A circuit draws only as much current as it needs. Extra current from the power supply is not used. A car battery can supply hundreds of Amps to a car's starter motor and can also supply only a few micro-Amps to a clock.

A higher current adapter has a voltage that doesn't rise as high as a lower current adapter when they have a small load current.

If you exceed the output current rating of an adapter then its voltage will be low, its ripple will be high and its temperature might be high enough to melt it.
 
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