@admin - sorry, I posted this in FB & suggestions by mistake!
I am trying to build a split supply for some op amp circuits. I came across this circuit http://www.instructables.com/file/F4XPE5WH3Z3UFPV
I'm a bit of a n00b to all this and I simply don't "get" it at all.
I tried it in a simulator and then built it. In both cases, I get the requisite +12/-12v, so what's the problem then?
The problem is when I try to USE it! If I connect an led(+ 470R resistor) between 0 and +12V then the -ve side drops to -19 and the "+12" is now +5v. Any "load" on either side totally screws up the "balance"
I have a theory...if it's right, I'll go "Eureka!" and carry on gradually learning electronics...if not, my head will probably explode and I will have to accept I have far more learning to do than I thought. Your help is therefore appreciated:
I'm using a wall-wart, not a battery. I'm thinking that "-ve" here is genuine, earth-potential 0v and that the wart isn't "floating". This is sort of "confirmed" as it has a metal earth lead rather than a dummy plastic one.
Also in my simulator, it won't run until at least something is at ground potential...hence same results in sim?
Hmmm - i tried it with a "floating" supply (plastic earth pin) and a battery pack...my theory is wrong, my head now explodes as any "load" above the 0v rail causes major changes in values of + and - rails no matter the type of value of the input supply
What am I missing?
heeeeeeeeeelp!
I am trying to build a split supply for some op amp circuits. I came across this circuit http://www.instructables.com/file/F4XPE5WH3Z3UFPV
I'm a bit of a n00b to all this and I simply don't "get" it at all.
I tried it in a simulator and then built it. In both cases, I get the requisite +12/-12v, so what's the problem then?
The problem is when I try to USE it! If I connect an led(+ 470R resistor) between 0 and +12V then the -ve side drops to -19 and the "+12" is now +5v. Any "load" on either side totally screws up the "balance"
I have a theory...if it's right, I'll go "Eureka!" and carry on gradually learning electronics...if not, my head will probably explode and I will have to accept I have far more learning to do than I thought. Your help is therefore appreciated:
I'm using a wall-wart, not a battery. I'm thinking that "-ve" here is genuine, earth-potential 0v and that the wart isn't "floating". This is sort of "confirmed" as it has a metal earth lead rather than a dummy plastic one.
Also in my simulator, it won't run until at least something is at ground potential...hence same results in sim?
Hmmm - i tried it with a "floating" supply (plastic earth pin) and a battery pack...my theory is wrong, my head now explodes as any "load" above the 0v rail causes major changes in values of + and - rails no matter the type of value of the input supply
What am I missing?
heeeeeeeeeelp!