Splitting a supply

[jackinnj]

A circuit similar to this appeared in the most recent issue of AudioXpress ("MaxxBass Subwoofer") for splitting a wallwart supply into regulated +/- 5VDC -- this one won't oscillate!

An externally hosted image should be here but it was not working when we last tested it.

 

[Steven]

...this one won't oscillate!

But it won't work either. Your biasing is wrong, trying to force the opamp output to a negative voltage compared to the non-inverting input, which is at the negative supply rail of the opamp.

Steven

 

[jackinnj]

Re: Re: Splitting a supply

But it won't work either. Your biasing is wrong, trying to force the opamp output to a negative voltage compared to the non-inverting input, which is at the negative supply rail of the opamp.

Steven

I flipped the OPAMP (vertically) by mistake -- mea culpa -- incidentally, the schematic is also on National Semi's website --

 

[jackinnj]

here's another go:

An externally hosted image should be here but it was not working when we last tested it.

 

[djk]

Radio Shack sells several wall warts that are AC, I bought one the other day to replace one in a JBL BX63 electronic crossover.

Half wave rectify it for both supplies, then regulate it.

 

[darkfenriz]

doesn't it multiply the input offset voltage of the opamp by 15x
????
with the regulated voltage that small may be noticable...
am I right??

 

[jackinnj]

Radio Shack sells several wall warts that are AC, I bought one the other day to replace one in a JBL BX63 electronic crossover.

Half wave rectify it for both supplies, then regulate it.

I have used an AC wall wart from a Sony answering machine -- you use a voltage doubler -- the ground is the junction of the two capacitors which are attached to the AC source.

 

[AndrewT]

Hi,
what's the lowest supply voltage this circuit can accept?
output=10Vdc
Min input =? when loaded.