Electronic question: Power supply

[LarryN]

My Casio calls for a 9 volt DC, 800ma power supply. I have a 10 volt DC, 1100ma supply. Can I use 10 volts safely? If not, can I use a resistor to drop the voltage, safely? Thank you to anyone who knows this stuff. I know to make sure the center is negative.

 

[keyplayer]

I wouldnt do that....even tho you might get away with using 10 volts instead of 9, the difference in ma is 300....that makes the milliamps more dangerous with the 10 volts.....if you have to use something that isnt original, go to radio shack and get one of those universal adapters that has 3 or 4 diff voltages and connections and make sure if the voltage and amps are wrong, THEY SHOULD BE WRONG ON THE LOW SIDE

BTW, you can probably order the right one from casio

 

[LarryN]

Thank you for your reply. Would 500ma be safe? I have one with that rating. I'll get the right one but want to play now without using batteries.

 

[keyplayer]

500 ma shouldnt hurt it if the other side is 9 volts...as a matter of fact, it may not run on 500 if the original is 1100....thats less than half

 

[LarryN]

The supplies I have seen on the Casio WK-110 I have are 800-850ma. Will it function on 500? I guess I could try it, since it probably wouldn't hurt the keyboard.

 

[keyplayer]

somewhere on the keyboard or on the owners manuel it will tell you the power specs

theres no way of knowing the tolerances of what the board will take without hurting it...do the right thing and order the correct power supply

 

[LarryN]

Too bad Casio makes it so involved to buy a simple power supply. I went to great lengths to buy one. They should come with the unit. Of course nobody can resist the chance to make an extra buck. I have one on order. Thank you for your help, keyplayer. I'm amazed at the tones on the WK-110 for the money, anyway. I don't need much more than piano, organ and pads for my recording.

 

[keyplayer]

good luck man!.....i was just gettin nervous for ya....hate to see you burn somthin up....LOL!!

 

[davesch]

I may be a little late here, but just in case...

I wouldn't use a 10V supply when 9V is specified. It might work, but the extra voltage may cause damage over time. A couple of diodes in series could be used to drop the voltage. Don't use a resistor as the voltage dropped will depend on the load which will vary with volume etc.

However there are other issues:

Is the power supply regulated ? If not the voltage may vary dramatically depending on load.

Are the polarities the same ? Some supplies have positive inner pins and negative outer pins, others the other way round. Get it wrong and it could be a puff of moke. Also some supplies are DC output, some AC. Use an AC supply when DC is required and you will definitely do damage.

Don't get too hung up on the mA rating, that just says how much current the supply can source. As long as the value is the same or higher, it's not an issue.

 

[LarryN]

I bought a 9-volt 800ma supply, but I don't know if it's regulated. It doesn't indicate. I've heard that some keyboards are internally regulated. What to do? I'm going to put the right tip on and reverse the polarity. Those batteries are working great! Could you say something about what regulated supplies do? Thank you for responding, davesch.

 

[davesch]

Hi, in an unregulated supply, the voltage will be higher than stated with no load, but will decrease when the load is applied. Regulated supplies have circuitry to hold the supply at a steady voltage. I don't think you can assume the keyboard will have regulation circuitry.

Chance is that you will be okay, but I cannot give that guarantee. The only way you can be sure if not stated as regulated is to find someone with a voltmeter who can check it.

...and please make sure you get the polarity right, I cannot stress that enough. Any keyboard or appliance maker with good sense will add a diode to the equipment to prevent damage if a reversal occurs, but my experience of repairing electronic goods is that many don't for the sake of saving 10p.