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wall wart/transformer instead of batteries? Answered

I have recently purchased a creative HQ-2300D and it only accepts two AA batteries for powering the decoder, there is no DC in on it. Can I use a wall adapter to power it? (it really eats batteries)

The intended transformer.

nokia charger, output is 3.7v = / 355mAh

The reason I am wanting to use a transformer with it, is it would make it a lot easier as it is only used for gaming on the xbox 360 (to get the dolby headphone from the decoder) so it is never used "on the go" so changing the batteries/ recharging them is a mild annoyance I wouldn't have from a transformer turned on when I use the 360.

It can't be as simple as wiring pos to pos and neg to neg on the battery terminals inside the decoder with the nokia charger because there is only a slight variation in the voltage.....can it?.

I am also concerned about whether the transformer is regulated or not, reversing polarity, correct polarity etc. etc. and what else is important not important when attempting to do such a thing, so as not to destroy my decoder. (I did this before with a minidisc player and a Universal adapter on the wrong voltage, I didn't impress myself..........doh.... anyone smell that....)

I tried plugging the nokia charger into another 3v device (an old sony tape deck) that has a 3v DC in, and it didn't seem to give it enough power to turn the tape, but when I plugged in a universal adapter and set it to 3v it worked fine.

My idea is to remove the fem connector from the phone and rig it so it can be plugged into one of the battery terminals and the nokia tranny can be plugged into it, but it can still be removed for when I want to use batteries.

I put it to all those with the knowledge who can explain in lay-mans terms and educate me on the best, safest, cleanest way to solve my dilemma.




10 years ago

i am getting some parts in ready for this project too, i am hoping to run a little headphone amplifier, that uses 1.2v AAA battery off the 'mains' i have the croc clips on order and am looking to find the right wall adapter, but seeing as the amp only takes 1xAAA@1.2V, i need to match that input from an adapter, and none go that low that i can see, they start at 1.5v.....which i guess would be too much!?! the amp uses a voltage multiplier chip for the output @ 5.5v but i need to match the input! any pointers for you fellow instructables much appreciated Q

When I found this post I thought you wanted to make an AC adapter to replace a battery @3.7 volts? This is what I'm looking to do. I've been scrounging around the site but I haven't found anything that lets you replace a standard LiPo or Lion battery (3.7) with a mains charger. I have a mains-to-USB wall wart that I want to lower the voltage from 5 down to 3.7 volts. I am trying to make it as small as possible, the load is not even 150ma. Surely there is a better way than putting a resister to it? I have a similar goal for a 3-AAA battery pack. I wish to lower the voltage from 4.5 down to 3.7 Can anyone point me the right way? Thanks

Hi Quaddy I done pretty much what your thinking of doing. I too have used croc clips on the pos & neg connections in my little creative decoder and I ditched the nokia wall wart (as recommended) I was originally intending on using. I used a regulated universal wall adapter (check maplin) instead, and set it to 3v and all is good, works a treat. most rechargeable AA or AAA batteries are 1.2v but if they are alkaline they are likely 1.5v ( I have two 1.5v alkaline in my T.V remote) so an adapter that is 1.5v will do the job, would make sure to get a regulated one though (has worked for me).

Hey py3m4n, thanks for the snippets of info, about alkaline output and regulated. have taken this on board and ordered a suitable (hopefully) adapter from ebay, as maplin didnt have regulated any higher that 500mA, the only think that i was puzzled about was the mA requirements, as my headphone amp doesnt detail any power specs at all, as its a home brew affair and the batteries i have used vary in mAh, i opted for the 1000mA adapter rather than the lower maplin 300 or 500mAh types. pot luck on that element. will post back in a few days, see if it isnt fried bit of pcb then :)

1) a regulated transformer gives a steady voltage. an uregulated on gives its rated voltage only under full load. otherwise, it gives more votls 2) 2 AA produce 3 volts, not 3.7. assuming your charger is regulated, it could be okay. if there is no regulation, chuck the transformer and buy another one.

Yes, I agree. Most gadgets either step down or boost up the voltage anyway to get it's desired voltage. So they are often very tolerable for moderate under/over voltages. Chargeable batteries are only outputting 1.2 volts compared to standard batteries that are1.2. So a camera that uses four batteries must work just as good on 4.8 volts as 6.0 volts. Regarding eating of batteries... In the beginning of the digital camera era I had a Olympus camera. If I used regular batteries I got about 5 shots before they were drained. When I replaced them with good rechargeables (think they were 1200/1400 mAH at that time) I got atl east 50 pictures on one charge.

same here. its also worth noting that, eventually, rechargables loose their ability to stay charged. my first set of digicam batteries lasted a year. then they could no longer power the camera. they still work fine for other junk though.

Yep. Thats how my batteries are now. They die after about a day of use in the camera.