wall power control circuit help

control circuit help

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.

Re: control circuit help

As this power supply has floating output you can create so called "rail splitting virtual ground" ..
To do so, set the output voltage to just above 6V and divide it into two identical halves, and use the middle point of that division as your new "virtual" ground
More details here:
https://tangentsoft.net/elec/vgrounds.html

IanP
:|

control circuit help

thanks for the reply. so if i configure a circuit using the same components as in the diagram, the V+ terminal will be +3v and the V- will be -3v?

sorry im pretty new to all this electronics stuff.

how do i reduce the 9v to 6v?

when i split the 6v, can the gnd for the wall power supply can be connected to the same vground as the one between the r3 and r4?

i assume r3 & r4 = 1Ω?

thanks again for the help, wouldnt have been able to do this on my own.

Re: control circuit help

how do i reduce the 9v to 6v?

Click to expand...

To drop voltage from 9V to 6V you can use LM317 voltage regulator or you can use 3-4 x 1N4004 diodes connected in series, each diode drops roughly 0.7V ..

How stable is the 9V from your wall power supply and how stable - do you think - the +3V and -3V should be?

when i split the 6v, can the gnd for the wall power supply can be connected to the same vground as the one between the r3 and r4?

Click to expand...

Wall power supply [-] becomes -V, wall power supply [+], after you drop voltage from 9V to 6V, becomes +V ..
VGND is "new" , just created locally ..

IanP

Re: control circuit help

IanP said:

To drop voltage from 9V to 6V you can use LM317 voltage regulator or you can use 3-4 x 1N4004 diodes connected in series, each diode drops roughly 0.7V ..

How stable is the 9V from your wall power supply and how stable - do you think - the +3V and -3V should be?

Click to expand...

ok, lm317 to drop voltage, and the wall source should be pretty stable, but can i hook it up to a multimeter to check that?

the +/-3v should be fairly stable, within 5% i think would suffice. given that its normally run off of batteries which provide different amounts of power throughout their lifespan, the circuit should be fairly robust.

IanP said:

Wall power supply [-] becomes -V, wall power supply [+], after you drop voltage from 9V to 6V, becomes +V ..
VGND is "new" , just created locally ..

Click to expand...

maybe i am misunderstanding, but i thought the +/-V's from the diagram were the outputs and the 6v was my input. i understand that the vground is created, but where does the actual connection for gnd from the wall power supply go?

did a quick sketch that may or may not help,

Re: control circuit help

Have a look at the attached picture ..

in the vgrounds page you linked it talks about the TLE2426 component being a rail splitter. would you advise using that in such a case or just configuring a pnp/npn set up with capacitors?

i also ordered some adjustable voltage regulators and stock 3.3 and 5v regulators.