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making a variable -5V to 5V voltage source

P

panfilero

Jan 1, 1970
0
ok... I would like to be able to apply a voltage range of about -5V to
5V across a load, and all I want to do this by varying a 0-10V power
supply..... here's what I'm thinking about doing....

Use two opamp buffers, on one of them I will pass my 0-10V and on the
other I will be passing a 5V reference

The load... which is about 56Kohms will be connected across the
outputs of the two buffers

I am thinking that as I sweep my 0-10V, I will be sweeping -5 to 5V
across my load (since one side of my load is at a steady 5V reference,
as I sweep between 0-4.99 I'll be negative, and from 5.01 to 10 I'll
be positive)

is this design ok? what I'm unsure about is my current will be
constantly being sourced from one opamp and the other will be sinking,
and then visa-versa.... is it ok to wire two buffers like this and
send the current from the output of one into the output of the other?

I have particular interest in a region where my load will be pulling
around 50uA.... does this matter? Will the opamps be adding any
current to my load.... I don't think so...

any thoughts are appreciated, much thanks!
 
J

J.A. Legris

Jan 1, 1970
0
ok... I would like to be able to apply a voltage range of about -5V to
5V across a load, and all I want to do this by varying a 0-10V power
supply..... here's what I'm thinking about doing....

Use two opamp buffers, on one of them I will pass my 0-10V and on the
other I will be passing a 5V reference

The load... which is about 56Kohms will be connected across the
outputs of the two buffers

I am thinking that as I sweep my 0-10V, I will be sweeping -5 to 5V
across my load (since one side of my load is at a steady 5V reference,
as I sweep between 0-4.99 I'll be negative, and from 5.01 to 10 I'll
be positive)

is this design ok?  what I'm unsure about is my current will be
constantly being sourced from one opamp and the other will be sinking,
and then visa-versa.... is it ok to wire two buffers like this and
send the current from the output of one into the output of the other?

I have particular interest in a region where my load will be pulling
around 50uA.... does this matter?  Will the opamps be adding any
current to my load.... I don't think so...

any thoughts are appreciated, much thanks!

Sounds good, including the load current, which is tiny. The depends
only on the voltage across the load.

If you want to reduce the required power supply voltage, swing both op-
amp outputs in opposite directions between 0 and +2.5 volts.
 
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