Electricity question

Aug. 29th, 2009 12:24 pm
I have 3 guitar pedals, that take 9V DC power. The current draw on each one is 17mA, 20mA, and 55mA respectively. Mains power here is, what, 220-240V, 13amps? The AC/DC transformer is going to use some power itself, but I would have thought that getting 90mA from one power source would be easy.

So why does the guitar shop recommend power supplies like this one which cost £100? Surely I should be able to just take a normal 9V DC supply and run it in parallel to each pedal?
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electrical question for "y'all"

Apr. 23rd, 2006 11:23 pm
thedarkproject: (anubis)
I had 2 guitar pedals connected on the same cable from an AC-DC converter, and the output when passed through both pedals in turn had a loud 100Hz hum added to it. I took them off that power cable and onto 9 volt batteries, and the hum was gone. So, 2 questions: (1) Any idea why that hum was getting through the conversion to DC power, and (2) Any idea why it was 100Hz and not 50Hz? Did the 2 tones just happen to be 90° phase shifted relative to each other or something?
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  • Current Music: October Tide - "Floating"
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