• Add an AC adapter to a battery-powered device

    Hi! I came across this instructable and I have the same question as LearnEveryday71, with the difference of my tag does not state .25W, I see a 20 ohm resistor soldered to the switch for one set of string leds. I am thinking if I solder two sets together, I would have to add another 20 ohm resistor in series to it or replace it with a 40 ohm. Also, I would have to buy a 9V dc power supply. My question is what amperage power supply should I get? Thanks for any advice you can give.Here is the post from Learneveryday71:Kelseymh, please educate... I have 2 battery powered LED light strings. 20 lights each string. The tag on each string reads: 4.5v DC (3, 1.5 AA's) .25W. I want to wire both together into one string so I can solder a transformer plug. Then buy the proper AC/DC transformer at radio shack or online to plug it in to house current. Now the questions ... If each string is 4.5v, and I want to connect them together, do I need a 9v, 100ma transformer? Do I worry about Ohms or wattage when crunching the math for the proper transformer? Any advice, tips or education you can provide would be appreciated!

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