wall power control circuit

[Xenosis]

id like to create a control circuit that takes a standard wall power supply (outputs 9v) and run it through a breadboard power supply (like this one) and has two output terminals; one with +3v and one with -3v.

this is being used for a robotic arm that is currently run off of batteries that are set up in the -3v and +3v config.

if its easier to just strip the wall power supply to vdc and gnd pins and use that with a breadboard, i could do that also.

 

[KMoffett]

From the looks of the circuit board, they're using a LM317 adjustable regulators. The output is set to 3.3V. It could be tweaked to 3.0V. An LM317 requires (per spec's) an input 3V greater than its output. So for +3V out you would need +6V in. To get +3V/-3V, you would need 12V in. Those boards' outputs can't be stacked: +3V/com/-3V with one transformer winding input, even if it were 12V instead of 9V. If you are going to use those boards you would need two separate 6V wall warts.

Ken

 

[Xenosis]

say i get a 12v wall power supply, could i combine the 5v and 3.3v lines maybe via a one way diode/capacitor/op amp configuration and then split off 6v to then be divided into +3v/-3v ?

thanks for your reply.

 

[KMoffett]

No, That won't work.

Ken

 

[Xenosis]

How would I go about accomplishing this +3v/-3v split not using the breadboard power supply?

It seems more viable using this vground method, https://tangentsoft.net/elec/vgrounds.html, but I'm not experienced enough to be able to do the calculations necessary. I can build a schematic and take component measurements, but that's about it right now.