I'm working on a hobby circuit that is powered by 6 volts and regulated to +5 volts and -5 volts. It uses the +6 volts as ground. I've tried to attach part of the regulator below.



The circuit has several op-amps which are all powered by +5 and -5 volts. The inputs on the amps are using ground (+6V) to (in+). Hopefully as can be seen in the photo below.



I've built this circuit before and it does work although with some instability and oscillation. I'm adding decoupling caps and considering using one side of the pcb as a ground plane. I've read part of most of the data sheets and they indicate locating, usually a monolithic capacitor, as close to each IC as possible between -5v and +5v. My question concerns the +6 volt ground. If I create a ground plane should it be with +6 volts or -5volts?
I can't quite comprehend why the +6 volt ground. Anything to do with "differential"?

Thanks for being here!

 

Yes, the +6v will be the ground for the +5v -5v.

I think this schematic will boost the 6v to ~12v in relation to the gnd of the battery.
If you use the +6V as gnd for the rest of the schematic this will give you -6V and +6V

However you only posted half of the schematic, there should be a PWM source driving the FET/transistor if im not mistaken.
Could you post the full schematic in better resolution?

 

I can't quite comprehend why the +6 volt ground.

The 6V is the power source so normally everything is referenced to that ground.
But you can you can use any point as "ground" if you like, as it's just an arbitrary reference point.
However that can mess up the signal circuit bias.
For example, if you use -5V as ground, then the op amps would be operating with a voltage of +10V and 0V with respect to ground, instead of ±5V as desired.

 

Thanks Guys! This is something I've been contemplating for a few days. I generally try to research and read but that requires a topic. I wasn't sure how to ask the question or how this circuit works.
crutschow, looking at some of your projects I saw this , "High-Side Current Source with Differential Inputs". The regulator in my circuit may be similar. It uses a 4093 to drive the fet/transistor , has a NE5534 and 2 LM393's.
The complete schematic is huge. It takes 2 pcb's , one measures 6 inches by 9 inches and the other about half that. I've had 2 batches made of 5 boards each. I've been 1 year working on this, so far. Trying to read the schematic, lay the board out in Sprint and placing the parts. The only thing I'm pretty good at is soldering in the parts.
Before I order more boards, one more question. I'm going to use +6 volts as ground plane. I know I need decoupling caps between -5 and +5 supply to each IC. Do I need caps on the GRD to IC's?
Ok, one more question... How do you get _ under + in your posts?

Thanks

 

I'm going to use +6 volts as ground plane. I know I need decoupling caps between -5 and +5 supply to each IC. Do I need caps on the GRD to IC's?

Yes.
Instead of putting the caps from plus to minus, put caps from plus to ground and minus to ground.

How do you get _ under + in your posts?

What?