Virtual ground

[Mike(Mont)]

Figured it was easier to start a new thread but it's the same problem--coil goes to ground and I want to isolate it from the other circuits. The battery (voltage regulator), the signal generator all go to ground and I do not want the coil signal connected to these.

It just seems like this is what i might need but have no electronics knowledge here. I've watched some videos on this but that's as far as i got. I would appreciate if if anyone could steer me to a place I could learn more about this in order to design something. Thanks.

Well, at least I think that is what I need. Not really sure about anything here.

This article talks about the TLE2426 noise reduction.

https://tangentsoft.net/elec/vgrounds.html

Pretty sure I am over my knowledge ability here so don't anybody spend too much time on this or you will get frustrated with me for sure.

This is not your regular coil circuit and I think I need to get some professional help. I mean WITH THE CIRCUIT!!!

[Geo]

The schematics that there are at linked page are to supply with symetrical voltage the op. amplifiers from a simple supply.
BUT i can't understand what you want to build so to say if schematics are ok or not.

[WM6]

All explanation you can find in link you give to us here.


Apart from dual power supply all other solution are based on resistor divider solution.
This one (taken from your link):



So you need to start with voltage divider theory to go further with understands.

Geo proposed you, couple days ago, to post your idea/schematic or at least part
of those schematic to make discuss and help possible. This is still valid.

It's not uncommon to see multiple grounds in a circuit and it's normal for these to
be joined together at some point: either directly, or par example with a zero ohm resistor.

The reason you have multiple grounds is to control the return path for various currents.
Digital circuits for example may contain fast edges in signals and so have the potential
of introducing significant noise.

Separating the digital from analog ground allows you to keep the analog signals clean
of any noise from the digital switching.

The digital ground will contain noise but this matters less as you are only interested in logic
high or low; the exact voltage is less important.

The two grounds will be "starred" together at some point perhaps directly at the capacitor
lead of the power supply.

Those ground in circuit, that are not directly linked to (-) negative pole of power supply is
treated as virtual ground.

[Mike(Mont)]

Thanks for your help. Yes, this is not a typical coil circuit. I don't wish to describe it. But if you know how a pulse induction coil spikes--this is what i need to isolate from everything else. i will continue to study the virtual ground to try to isolate the voltage spike off the coil to ground.

[Mike(Mont)]

All this talk about flyback voltage I don't see any reason why I can't try a damping resistor to see if it will quiet things down some. Yeah, I'm desperate and grasping at straw, but never know until I try. Recall my motto "Cheap overkill". Finding the right value is the big obstacle but I can do it like Edison, just keep trying 10,000 times. I have the formula in the ITMD book but don't have all the numbers to calculate it with, so maybe I'll get out my dowsing rod and put a bunch of resistors on the table and see which one I get a lock on. Just a joke.

[WM6]

talk about flyback voltage I don't see any reason why
I can't try a damping resistor to see if it will quiet things down some.

You can. You should. Role of damping resistor is exact those - to quiet
wild oscillation (if R-damping is to high).

To find proper value of damping resistor it is better to use potentiometer
and replace it at the end with single resistor of exact value:

[Mike(Mont)]

Thanks for the info. Yes, part of the issue I see now is I am not using one set frequency. So i might end up with a rotary switch with several different resistors. I'll give it a shot today and see if anything improves.

[Mike(Mont)]

I didn't try a variable just a couple different resistor values to see if any sort of improvement. Not any difference. Kinda strange, thought there would be SOME difference. Now I am referring to the scream being emitted from the voltage regulator--not the coil itself. Didn't even check to see how it responded. it probably was effected. But not concerned about that part right now. Like I said this is not your regular coil set-up. I'm still going to pursue the virtual ground but I'm slow. And it just might not be in the cards. But I haven't waved the white flag just yet. But i admit i am running out of options or like they say swirling but not down the drain yet.

[Mike(Mont)]

I've got the white flag in my hand and ready to wave it. Probably take me a few more times getting skunked before i decide i need to get the coil ground isolated. I know an EE here I might get the courage to go ask him about it--or not.

[Mike(Mont)]

Virtual ground can sink little or no current. This will not work for me. White flag has been raised. I kinda figured as much from the start when i referred to this as a possible fatal flaw.

I'm just going to leave it as is and have some gasoline on hand ready to use after I get skunked a few more times. Ouch!!!

[WM6]

I didn't try a variable just a couple different resistor values to see if any sort of improvement.

Bad decision, sorry, to silent flyback oszillations R-dumping need to be set relative precize.

You cannot replace precize potentiometer (or trimpot) setting by couple of resistors.

[Mike(Mont)]

Okay, I understand.

I have another idea to try today. I will split the ground rail and run the coil straight back to the battery, then put a diode on the other part of the ground rail (near the battery). I hope this will block the coil signal from the rest of the circuits. I know sure sounds like a Wile E. Coyote idea.

[Mike(Mont)]

I'm optimistic that I might be able to possibly if all goes well hopefully maybe get a diode to work, but I don't have the right one--need a higher breakdown voltage. So order one and wait. Sorta like Wile E. Coyote waiting for the Roadrunner.

https://www.youtube.com/watch?v=wRSHzenjiNA

[Mike(Mont)]

All of a sudden i don't feel so optimistic any more. (no LOL here).

Flip-flop, flip-flop.
Now maybe there is still a chance. I hooked up a smaller diode to a LED circuit on the negative side and the LED still lit up so this is what I hope happens with the Contraption.

I'm so ignorant with this I wasn't sure the diode would even work on the negative side, but it appears to be okay. At least until i find out for sure I am going to breathe a little easier.

[Mike(Mont)]

So far, so bad.

I didn't have the right breakdown voltage so used a 50 volt and it did not help any. So looks like the Roadrunner is still running free and easy down the road I go. (Dirks Bentley)

Well, still just have to try the higher voltage diode when i get it. If that doesn't work I'll try one on the positive side, too.

The part is not supposed to be here until next Tuesday.

The waaaiting is the haaaaardest part. (Tom Petty).

Wished I didn't know now what i didn't know then. (Bob Seger)

I couldn't help myself, had to try it. Now I regret it because I'm seriously worried nothing is going to help.