plz answer question about voltage

[jimbob]

i sure this im right but i wanted to double check-- 12vdc  .3a is also the same as 12vdc 300ma?

[toneman]

correct
also,
point 3 is same as point 3 zero zero
2 convert amps to milliamps,
move decimal point 3 places to right.
thats .300 -- zeros are place holders for hundreths and thousandths.
same as the fraction 300 over 1000  (300/1000)
or, when fraction is reduced, 3 over 10 (3/10).
thats 3 tenths of an amp
or
300 milliamps

a "milli" amp is one thousandth of an amp.
U have 300 or them...
Use them wisely grasshopper
Oh Kay Now...
with all the above knowledge,
what is one thousandth of a milliamp.
Whohaaahahahahahahahah
please send 1000 dollars to my email box...
staytuned....4 the answer....
tone

[jimbob]

Thanks....so 1 amp or 1a is the same as 1000 ma?

[jimbob]

"This pedal can be operated on 9 to 12VDC. You must use a 2.5mm center pin DC Power Plug with positive on the pin. The minimum current that must be supplied is 200 ma."

thats what the manual says--i found a 12vdc 2.5 center pos but the current is 1a. It says minimum so im guessing its fine?

[SoundTech]

Yes, that should work fine.  The powersupply may actually put out more than 12VDC, depending on how well it's regulated, so watch it.  The thing it's powering will draw it's needed 200mA (or 0.2A) from the power supply and be happy.

[Mark Hammer]

As well, you can infer the current (if otherwise unstated) from composite voltage-current figures.  So, if the supply/transformer is rated as 15VA and you know it to provide 12V, then it delivers 12v at 12/15 = 1.25 amps.

[Boofhead]

So, if the supply/transformer is rated as 15VA and you know it to provide 12V, then it delivers 12v at 12/15 = 1.25 amps.

Actually that's only true for a transformer with a resistive load across the AC voltage of the transformer.  When you have rectifiers and filters the story changes somewhat - the DC output power is always less than the transformer's AC rating.

[Mark Hammer]

A little knowledge is a dangerous thing, isn't it?  I'll retreat from my position to this one:  If it says 15VA and is nominally rated to supply 12vAC then you know at least that it will likely deliver MORE than half an amp at 12v and probably less than 2A.

I learned this trick from presidents and other politicians: When embarrassed by specifics, obfuscate. :lol:

[jimbob]

A while back someone wrote here that the ac/dc adapter's never supplied exactly what they said they did---I learned this to be true!! Thanks all..You all possibly saved me $$$$$. I have a lot of 12v dc lying around and ofcourse they actually varied from 13.9 ect.. to even 18vdc. I also learned that a lot /most Boss stuff uses dc/neg center and EH I believe uses DC pos/center? Not too sure just yet about the EH (still researching that one..The thing is, i have an effect that uses 9vac/positive center pin..It can use dc but wont work properly--they were correct! Damn! Those Ac one's seem a lot more expensive versus the standard Boss.

[Boofhead]

Mark,  a lot of transformer manufacturers give out info sheets (many on-line) which show the formulas for output power and you can see it's lower.   The reason it's lower is because the current waveform in the windings is no longer sinusoidal and this causes the windings to heat-up more - hence the derating.