Step 5: Modify the Transformers

To open the chargers, you can use a variety of methods. I used all three of the following:

1. Find the crack in the transformer and pound at with a thin screwdriver and a hammer untill it cracks along the line.

2. Slowly cut the crack in the transformer with a utility knife.

3. Find the crack in the transformer and cut it open with a hacksaw

Find the + and - terminals of the transformer and unsolder the wires that were there. Resolder the wires from your DC Male plug onto the same points. Make sure you have the polarity correct!

Test the polarity with a multimeter, and if all is well epoxy the case of your transformers shut.

You can skip this step if your transformer already has the size N DC plug on it.
Your charger may very well work fine, but your schematic does not reflect a correct switch for switching power sources. Don't read into raw text - you don't seem able to do it well.
Well, I'm not the best with electronics yet.
Your schematic is missing the N connector and the other pole of the DPDT you show with the switch above with. This is a good instructable, but needs the simple change mentioned above for clarity!
Sorry,it might be a single throw, but I'm not sure. The switch only has two positions. Hope that helps.
The schematic is incorrect. The left leg of the 7805 regulator is IN. That is where the bat of the switch is located. The other end of the SPST switch should be to your N jack positive to use it to connect to an AC adapter instead of chewing up the 9V. Connect all grounds - don't use the switch! That way, your switch works to switch between power sources. Also, the parts list needs to be changed to reflect the change from DPDT to SPST - you don't switch the grounds. Ground is permanently connected. I guess the picture showing the switch can just go away if you correct the schematic as I suggest.
My charger works perfectly fine and I used the schematics in this instructable. My charger does not "chew up" the 9v battery at all since the leads from it are not leading to the circuit board unless the switch is in the battery position.

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Bio: Sometimes I make stuff.
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