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dual supplies

leeb_965

Feb 5, 2012
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hi,

how can i get a positive and negative voltage out of a single 3 port dc power source (+, -, ground)?

I need +6V and -6V for an op-amp
 

timothy48342

Nov 28, 2011
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Explain more. It sounds like you already have a + and - voltage if your "single 3 port" source is +. -, 0.

Describe your source more.
-tim
 

leeb_965

Feb 5, 2012
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yeah it is, see the attached jpeg.
 

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(*steve*)

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This is a single-ended power supply.

You need to either set it to 12V and create a middle rail or get two of them and connect them together to create a double-ended power supply.
 

(*steve*)

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It depends on the current you need. It could be as simple as a couple of resistors with capacitors across them, or an op-amp driving a pair of transistors.

This site evaluates a number of options.
 

leeb_965

Feb 5, 2012
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Can this be done with just the resistors? I need dual supply for a LF353N opamp which can go up to +-18V max. Im not sure if it needs to be a perfect balance between +6V and -6V
 

Harald Kapp

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Using resistors is an option as long as the current on the 0V rail is very small. If, however, you are going to drive e.g. an amplifier, you need a more powerful solution as *steve* suggested.

Can you post the model of this power supply? While it shows only a single readout for voltage, it still could be a dual supply. Otherwise I see no reason for the GND socket.
You can make a simple measurement: set the power supply to 6 V. Measure from "-" to GND, from "+" to GND. If the first measurement gives -6 V and the second measuremnet gives +6 V, then it is a dual supply. If the measurements give +-3 V, then it is a single supply (In that case I'm wondering what to do with the GND socket).

Harald
 

davenn

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While it shows only a single readout for voltage, it still could be a dual supply. Otherwise I see no reason for the GND socket.
Harald

My twin single rail PSU also has GND sockets

The reason is probably the same as the one shown by the OP
the negative is likely to be floating above the chassis where the GND socket is
connected to the chassis and hence EARTH :)

Dave
 

davenn

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nice supply :)

looks like it is as I described for my one

look through that link that Steve gave above there are examples down the page in there of how to turn a single rail supply into a dual one and ifthe only thing you are powering from it is the Op-amp then you shouldnt have a problem with current requirements :)

Dave
 
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davenn

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did you look through that cct collection in the link ?

most of the examples use at least 1 cap some of them use 2

Dave
 
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