tbrun
Newbie level 3
![Newbie level 3](/styles/images/ranks/alevel3.gif)
My 7 year old son has a toy robotic arm that uses 4 D batteries in series.
He had the idea to replace the batteries with a DC adapter so he could save some allowance $$ by not buying new batteries.
Seemed like a good idea until we opened it up and saw that it's not as simple as just a positive (+ red) and negative (- black). There is also a ground wire that connects to the middle of the battery series (between 2nd and 3rd batteries).
If I connect that ground wire to the negative (- black) line, the robot arm only goes one direction (up, right). If I connect that ground wire to the positive (+ red) line, the robot arm only goes the other direction (down, left). If the ground is not hooked up to either one, the robot arm doesn't work at all. If the ground wire is hooked up to both, of course it shorts the converter.
So the question is: how can I hook up the ground wire to make the robot arm work again in both directions? Or, is there some special property of a ground in the middle of a battery series that I cannot replicate with a DC adapter?
This is nowhere as easy as when I did this with his baby swing 6 years ago!
Thank you for any advice, much appreciated!!
:?::-?
He had the idea to replace the batteries with a DC adapter so he could save some allowance $$ by not buying new batteries.
Seemed like a good idea until we opened it up and saw that it's not as simple as just a positive (+ red) and negative (- black). There is also a ground wire that connects to the middle of the battery series (between 2nd and 3rd batteries).
If I connect that ground wire to the negative (- black) line, the robot arm only goes one direction (up, right). If I connect that ground wire to the positive (+ red) line, the robot arm only goes the other direction (down, left). If the ground is not hooked up to either one, the robot arm doesn't work at all. If the ground wire is hooked up to both, of course it shorts the converter.
So the question is: how can I hook up the ground wire to make the robot arm work again in both directions? Or, is there some special property of a ground in the middle of a battery series that I cannot replicate with a DC adapter?
This is nowhere as easy as when I did this with his baby swing 6 years ago!
Thank you for any advice, much appreciated!!
:?::-?