Convert 0-5v signal to -2.5v to +2.5v
Convert 0-5v signal to -2.5v to +2.5v
(OP)
I have a circuit that is converting a 4-20ma signal to 0-5v
the 0-5v was originally connected directly to the 0-5v input of an a/d converter. This Converter is now obsolete. The only drop in replacement is a converter that has a -2.5 to +2.5 input. I have an opamp on board that I can direct the signal tough before it gets to the A/D. Is there an easy way to use the opamp to convert the 0-5 to -2.5v to +2.5v. I am a computer programmer by trade. But my major was electronics. The problem is Its been 10 years since I have worked with an op-amp.
the 0-5v was originally connected directly to the 0-5v input of an a/d converter. This Converter is now obsolete. The only drop in replacement is a converter that has a -2.5 to +2.5 input. I have an opamp on board that I can direct the signal tough before it gets to the A/D. Is there an easy way to use the opamp to convert the 0-5 to -2.5v to +2.5v. I am a computer programmer by trade. But my major was electronics. The problem is Its been 10 years since I have worked with an op-amp.





RE: Convert 0-5v signal to -2.5v to +2.5v
(R3=R2=R1; R4=R5=2*R1 ; lets say R1=10K0hm)
One line === one net
---------------------------------
inp --- R1.1 ; noninv circuits
R1.2--- R2.1 --- opa.NONINV
R2.2 --- GND
+5V --- R4.1 ; inverting circuits
R4.2 --- R5.1 --- R3.1 ---opa.INV
R5.2 --- GND
R3.2 --- opa.OUTPUT --- ADC.inp
IN[V] OUT[V]
0 -2.5
2.5 0
5 +2.5
You may want to use voltage reference or measure the 5V
and rescale the result in software.
<nbucska@pcperipherals.com>
RE: Convert 0-5v signal to -2.5v to +2.5v
A little more info. This op-amp is currently supplyed with +5v and -5v.
RE: Convert 0-5v signal to -2.5v to +2.5v
I can't design for accuracy, offset VTG, etc.
R1,2 &3 are the same, R4 and 5 are twice as large.
The value and OP.AMP determines the offset error.
I would guess, you can go as low as R1,2,3 =1K
-------------------------------------------------
You could use just two resistors from current input
to + and -5V to get -2.5 to +2.5 --- if the power supplies
are accurate enough for your purpose.
<nbucska@pcperipherals.com>
RE: Convert 0-5v signal to -2.5v to +2.5v
sensor we would like to be within .1 inch overall error (This is the spec on the sensor) however it could be as high as +-.3
Thanks alot for your help.
RE: Convert 0-5v signal to -2.5v to +2.5v
to their junction -- it will change from -2.5 to +2.5.
<nbucska@pcperipherals.com>