syamajala Posted January 20, 2010 Report Share Posted January 20, 2010 My friend brought me a wallwart that he said he accidentally broke and would like to replace. I've been having trouble finding one that will work. The model number on it is mb132-060045. It is 6v dc at 450ma with a positive tip. I found some that are 6v dc at 500ma, so I was wondering if we could use one of those with a current limiting resistor. Would that work? Quote Link to comment Share on other sites More sharing options...
philetaylor Posted January 20, 2010 Report Share Posted January 20, 2010 No need for the current limiting resistor. if the device that it connects to requires 450mA then any 6v supply that 'can' supply at least 450mA is sufficient. You could use a 10A one if you wanted. The reason that you sometimes need a resistor to 'limit current' is when the device being powered has 0 (or very little) resistance of it's own. Ohms law tells us that Current (in amps)=Voltage in volts/Resistance in ohms. So a very low resistance device (like a forward biased LED) could (in theory) draw an almost infinite current. What happens of course is the LED goes pop! If you put a resistor in series with the LED then this increases the circuit resistance and stops you blowing the LED. Every device that you are likely to want to power will have a suitable internal resistance already! Cheers Phil Quote Link to comment Share on other sites More sharing options...
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