Power supply suitability?

[347sixtyseven]

Hi guys,

Just found a small power supply (i think you call wall wart?). It is rated at 9v 1000mA output.
Would it be suitable to plug in to my pedals? Would i have to reduce the output current?

If i were to make a cable up with multiple plugs on it, how could i work out how many effects i could run off this one power supply?

Sorry for so many questions 

Cheers

Gary

[frequencycentral]

That should run a sh!tload of pedals - you won't have to do anything to reduce the current.

But check the output with a meter - if it's not a regulated powers supply the 9 volts may vary substancially - not good. If thats the case you could build a little 'break out box' with a 7809 and some caps for filtering/regulating, and a bunch of outputs.

.........and, make sure it's DC not AC !!

[Roobin]

Well, first of all, do all your pedals run on 9VDC? Does your power supply output DC? If so, then you'll need to focus on the current requirements of your pedals. The 1000ma on your power supply tells you how much current a device can draw before the power supply overheats, burns out, etc. So you need to make sure that the combined current draw is less than 1000ma. To find out how much current a pedal draws there are 3 ways. 1) The pedal or a manual with the pedal will tell you the current requirements. 2) You can look up the current requirements based on other people's measurements - for example http://www.stinkfoot.se/andreas/diy/power/list.htm. Finally 3) you can measure it yourself if you have a 9V battery and a multimeter by hooking up one pole of the battery to the snap, then connect your multimeter between the free pole on the battery and the free battery snap pole. Then turn your multimeter to 200ma and measure the current draw. Try playing guitar through the effect whilst it is on, and try switching the pedal on/off, since these will give you an indication of the max current draw. You could check these values against the list mentioned above and/or the value given in the manual.

Once you have done this for all your pedals, add up all your current requirements for your pedals. This will tell you the max current requirement. If it is over 100ma, you might want to have a look at some commercial solutions such as the one spot. If it is under 1000ma, then current wise, it is ok.

The final thing you should check is whether the power supply is regulated. This means that whatever the load on the power supply (think of it as a resistor between the +/- of the supply) - even if it is 0 - then the output will remain pretty constant. If it is unregulated (which it probably is) then the voltage will decrease as the load increases. To see if yours is regulated, connect your multimeter to the power supply plug, one on the inside, on on the barrel, select the 20V mode, and read the voltage. A regulated supply will read about 9 - 9.7V. An unregulated supply will read about 11 - 12V. If your supply is unregulated, then you'll probably want to regulate it, since turning on more pedals will lower the voltage on each pedal. You could incorporate this into a neat splitter/distribution box. Search here for '7809' and power distribution - I think there's a project around here somewhere. Have fun!

[347sixtyseven]

Thanks for the very helpful info guys.

It is definitely DC output. It is unregulated though (just checked with MM and read 11.88v).

Will have to do a bit of research on the breakout box.

Any suggestions on making a cable/daisy chain for all my effects? Or should i just put a heap of output sockets on the breakout box and run individual power cables.

Thanks again

Gary

[347sixtyseven]

Could i just build the regulated power supply project at GGG and substitute my power supply for the transformer?

[frequencycentral]

Could i just build the regulated power supply project at GGG and substitute my power supply for the transformer?

Sounds like a plan - but you won't need the four diode bridge rectifier as you already have DC.

[347sixtyseven]

Cool.

Will those cap ratings still be okay at 220 and 100?

[frequencycentral]

Cool.

Will those cap ratings still be okay at 220 and 100?

Yup!