Turn an old battery powered drill into a wall power unit.

[Edit]
In the spirt of Instuctables, I'm adding some of the sugestions for improvement and why I didn't do things that way in the first place. Some I had considered, others i had not.

Q. Why not just put in new batteries?
A. Too expensive. The drill was $5 (with case, extra drill and 2 battery packs) and worked for a while. The wall wart was free at another garage sale. Brand new unit would be about $20 and be ready 'out of the box.' A new set of batteries and a charger for them would not be worth the time or money. If it was a good brand name on the other hand...
A. While trying to find out which cells in the battery were live and which were dead, I lost the parts. Thus, no battery shell to reload : )

Q Use a Zener transorb/5 f. capacitor/ect.
A Aint got one. Too expensive to go out and get some just to play with. I don't feel comfortable enough with electronics to risk the parts.

Q Use a more powerful transformer.
A Aint got one. That and i don't know how much I can pump threw the motor before it burns out. I may end up finding a bigger transformer, or trying it on AC current-but not untill I don't need this one any longer.

You may notice a theme here-this is a cheep fix with what I had on hand. Nothing fancy, not a lot of pre-planning to get in the way of getting something finished. Are there better ways to do this? Absolutely : )

Step 1: Research!

wall transformer for project power supply
https://www.instructables.com/id/EQ3VVA5ZVKEYF7HZ0W/
or
Reuse "Wallwart" transformers
https://www.instructables.com/id/EC1BYG2K40EWPKHAGV/
in a perminant way.

How to solder
https://www.instructables.com/id/E30LR180T4EWP872BS/
or
Soldering to large metal objects
https://www.instructables.com/id/EYUBQBN818EWZMIAYA/
if you are lazy like me and decide to solder onto the large battery clips rather than fiddle with the wires inside the case. or, you can't find your soldering gun but can find your butane torch...

you could even use
Handy box from scratch paper
https://www.instructables.com/id/EZO32EAKLOEXCFECUK/
for screws.

and, yes, i screwed up the batteries before i had a chance to use
Revive Nicad Batteries by Zapping with a Welder
https://www.instructables.com/id/EPV474YLF3EV2Z8V9V/
or
Hot Rodding a Power Drill Battery
https://www.instructables.com/id/EZOAB2A75XEV2ZHAQP/

Step 2: Gather Your Parts (and Tools)

First, look at the drill. On the side it will (hopefully) have a description of the battery pack. If it doesn't, look up what a replacement would be. In this case, an old craftsman drill used a 9.6 v, 1400 mAh battery pack. Then find an old, unused wall wart that might work-in this case, i found a 12 v, 1.2 A unit. I figure higher voltage will give a higher rpm, and the lower amperage means less power.

(1 A = 1000 mA)

What I used:

Craftsman Drill/Driver ($5 at a garage sale)
Wall wart (12 v, 1.2 A)
Screwdriver
Sandpaper
Soldering equipment
-butane torch
-solder
-flux
wire cutter (and stripper, if you want)

Step 3: Void Your Warrenty

Open up the drill.

It's useful to figure out which leads on the drill and power supply are which. If you don't, and the drill doesn't work, try switching leads around. It turns out that the speed control needs to be biased correctly. Who woulda thunk?

Step 4: Playing With Fire

Cut the end off the power supply. If I had the parts, I might have put a jack in the drill. Instead, it's perminent.

Strip and tin the ends of the wire. Sand, flux and tin the battery conecter. If you prefer, you could remove the battery clip and solder wire to wire instead.

Solder the power supply wires to the battery clips. Try and figure out why it doesn't work. Test power supply with multi-meter. Re-solder wires the other way...

Sorry, no picture of me soldering. It takes me two hands to solder and two more to hold the camera.

Step 5: Conclusions

Put it all back together.

It works!

Well, it works as a drill, which is what i needed. It only overpowers the first setting on the clutch, otherwise I can stop the motor with my hand.