Creating postive and negative voltages using LM350 positive regulator ?

Thread Starter

iinself

Joined Jan 18, 2013
96
Hi,
I am trying to create positive and negative 35V from 2 58V capacitor tied in series in the PSU unit of a old receiver. Will the attached circuit work for that?

Thanks
 

Attachments

crutschow

Joined Mar 14, 2008
23,742
What attached circuit?
You can't create positive and negative voltages with just capacitors.
You can split the voltage with a virtual-ground circuit to give a plus and minus voltage with respect to the virtual ground. Is that what you want to do?
 

crutschow

Joined Mar 14, 2008
23,742
The circuit you show requires separate isolated grounds for the circuits that will be using the plus and minus voltages.
Is that okay for your requirements?
 

Thread Starter

iinself

Joined Jan 18, 2013
96
The circuit you show requires separate isolated grounds for the circuits that will be using the plus and minus voltages.
Is that okay for your requirements?
It is for LM3886 amp, I am trying to generate + and - 35 V with common ground for the amp.
 

AnalogKid

Joined Aug 1, 2013
8,221
Hi,
I am trying to create positive and negative 35V from 2 58V capacitor tied in series in the PSU unit of a old receiver. Will the attached circuit work for that?
Nope. What you drew is an incorrect version of an old trick for using positive 3-terminal regulators in a +/- power supply. As pointed out in #5, the circuit requires two isolated sources because the negative regulator is regulating the ground, not the - output. This usually comes from two isolated transformer secondary windings. If your +/- bulk DC sources already have a common ground, then you need a true negative regulator IC as in #4.

ak
 

crutschow

Joined Mar 14, 2008
23,742
The combination of a LM350 and an LM333 will not work with a virtual ground if the plus current exceeds the minus current (as it will be with the LM3886 on the positive signal peaks) since the LM333 cannot sink current under those conditions.

The best way to use the LM3886 with a single supply is shown in Figure 3 of the LM3886 data sheet.
 
Top