+5VDC to -5VDC

[eblc1388]

The PIC A/D converter recommended input source impedence should be less than 10K so the following circuit is well within limit.

Let's wait for other's response.

 

[audioguru]

We are analog geeks and like opamps. We'll use them whether they're needed or not. We nearly added a second one as an inverter. The LM358 had a spare opamp anyway!

Ebic, you are brilliant to cost-analyse a really cheap solution. :lol:

 

[leonel]

Allow me to do one stupid question :lol: !! My pcb board will anot have an impedance associated? Or this impedance doesn't matter?
I'll do the circuit without opamps because pcb space problems and if it works it's cheaper

 

[audioguru]

As long as your pcb isn't made from dried mud, its impedance will be fine. I have some fake Veroboard that stinks like it is made from dung, and it causes leakage when the humidity is high. The stinky stuff conducts when slightly damp!

 

[eblc1388]

Allow me to do one stupid question :lol: !! My pcb board will anot have an impedance associated? Or this impedance doesn't matter?
I'll do the circuit without opamps because pcb space problems and if it works it's cheaper

Of course your pcb board have added impedance, but its effect is insignificant because your input load is so low at 200 Ohms and is driven by a current source.

Just remember to connect the voltage measuring point very close to the 200 Ohms resistor instead of at the incoming connection of the pressure sensor.