How to add an AC adapter to a battery-powered device

With a new baby, we are acquiring an astonishing number of battery-powered devices ? bouncy seats, swings, activity jumpers, mobiles, ? ? and burning through an even more astonishing number of batteries. Now I know why Costco sells those immense packages of AAs.

My wife asked me whether I could attach an laptop  AC adapter to our baby?s mobile. I?d seen an article in MAKE about modifying noisy toys, so I knew it was possible. It turns out to be surprisingly easy, provided you (okay, I) don?t make some dumb choices along the way.

NOTE The project I describe will void the warranty for whatever toy you modify. The manufacturer (rightly) will not support you or provide you with assistance in doing this. If it works, be happy: If You Can?t Open It, You Don?t Own It. If it doesn?t work, take it as a lesson not to meddle in the affairs of Corporations, for they are Subtle and Quick to Anger.

1.This Instructable is Incomplete

You?ll notice that two of the Steps don?t have useful images. I started writing this up after completing the project on one of our daughter?s mobiles, and before starting the second. I definitely don?t want to take the first one apart again just for some photos, and we?ve since decided not to d?

2.What to modify? A mobile
First, choose the toy you want to power from the wall. I?m going to show you a very nice infant?s mobile from Tiny Love. The steps will be similar for whatever device you choose, although the internal details (and maybe the screwdrivers) will be different.

3.What do you need? Parts and Tools
The parts you need to add an AC adapter (HP DC359A AC Adapter,hp Pavilion DV6000 AC Adapter)are fairly simple, but harder to find than I expected. I ended up going to Radio Shack ? they carry specific-voltage adapters, individual tips, and panel-mount sockets to match the tips. At most places you have to by a ?universal? adapter, and can?t get ?

4.Open the Box
Remove the batteries first; soldering the terminals with the batteries in place isn?t the best idea. Open the mobile using the triangular bit on the four back-panel screws. Be careful when opening up the mobile, as the wires inside do not have a lot of slack. Identify the red (+) and black (-)?

5.Prepare and mount the socket
Drill out the 21/64″ (5/16″ plus a little) hole at your mark for the AC adapter socket. The threaded end of the socket needs to stick out far enough to tighten the nut. You may need to clear some additional plastic from the inside in order for the socket to fit snugly up against the curved surfac?

6.Move the existing wires
Disconnect the red and black leads from the battery terminals using the soldering iron, and the solder-sucker if necessary. Make sure you keep track of which terminal is which!Solder the red lead onto the center pin connector (at the 9 o?clock position) of the AC socket. This allows the AC adapter?

7.Reconnect the Batteries
This AC socket includes a normally-closed switch on the shell (ground), so that you can power your device as built with the batteries, but when you plug in the adapter the batteries are disconnected (and not shorted to ground or reverse biased).Strip the ends of the black wire (and cut it to a ni?

8.Validation: does everything work?
You?re now ready to verify that you haven?t fried the device. First, set up the AC adapter(hp Pavilion DV8000 AC Adapter) by plugging the Size ?M? Adaptaplug into the end of the adapter cable. Make sure that the ?(+)? mark on the plug is aligned with the ?TIP? mark on the cable. This specifies that the center pin is positiv?

9.Close it up
With everything working, you can close up the unit. Carefully fold all of the leads into the space between the case halves (use bits of painters tape to hold them down). Insert and tighten the case screws. Put the battery compartment case back on.Now you can put the unit back into action, powe?