Finding the right AC adapter.

August 28, 2009 4:46 PM

Where can I find a 2/3a 700mAh 2.4v AC adapter?

I am trying to convert my battery-operated rechargeable beard trimmer into a "wired" trimmer. (The battery was dying, and it wasn't able to run off AC, so it was pretty much useless.

If I can' t find the exact right AC adapter, which numbers can I fudge? Is it ok if the voltage is the same but it's 10 amps? If the amps are correct, can I get away with a voltage of only 1.2?

posted by brenton to Technology (6 answers total)

Voltage must match exactly or within at most 10%. Generally most adapters will supply that amount of current.

Radio Shack and places like that usually sell AC adapters that have a selectable DC voltage output.
posted by GuyZero at 4:49 PM on August 28, 2009

The voltage must be the same (perhaps up to 3V, I'm guessing). The rated current must be 0.66A or larger. 700mAh is irrelevant in this context (it describes the battery capacity).
posted by fatllama at 4:58 PM on August 28, 2009

mAh is current * time, i.e. total battery capacity. The actual current draw will be that number divided by how long the battery lasts... so if it lasts normally for 20 minutes of shaving, you're actually using 0.7 / 0.333 = 2.1A of current so will need a 2.5A adapter. Or if the battery lasts for 2 hours of shaving, it's using only 0.7 / 2 = 350mA of current.

A 3V adapter will work but the shaver will run hot and fast. It sounds like it's a pair of NiCd or NiMH cells, so you might be able to bust the pack open and replace the cells with AA or AAA replacements - you can buy them with solder-tabs on them from electronics stores. And make sure the adapter has a regulated DC output.
posted by polyglot at 6:14 PM on August 28, 2009

I agree with polyglot that you should be able to disassemble and replace the NiCd batteries if you have access to a soldering iron. Go to digikey.com and search for "nicad battery pack". You can then filter for 2.4V and matching mAh. The mAh rating likely will be printed on the side of your current battery. If not, just go for the same size and shape. Brand name is not important. With some browsing you should be able to find a match.
posted by JackFlash at 8:11 PM on August 28, 2009

Response by poster: Cool, thanks for the info. If I can' t figure out how to set it up to be plugged in, I'll see about getting a battery, that sounds like it might be easier. I'd prefer it to be wired though since I hate having to remember to charge it (it won't run on AC when plugged in if the battery is low).
posted by brenton at 12:12 AM on August 29, 2009

Whenever I need a oddball wallwort (transformer) I go to the local thrift store, there is usually a basketful of them.

Just a thought.
posted by blink_left at 11:24 AM on August 29, 2009