hello…
i need +10v to -10v analogue output voltage for BL2000 rabbit microprocessor. i try to use it as PID controller in my project. BY default i only getting 0 - 4.11v analogue output from DAC0. how can i scal and buffer this output.
please help me…
thank you
This can be done fairly simply with an op-amp. Look here:
http://hyperphysics.phy-astr.gsu.edu/Hbase/Electronic/opampcon.html#c1
(The differential amplifier circuit shown at:
http://hyperphysics.phy-astr.gsu.edu/Hbase/Electronic/opampvar7.html#c1
may be where you want to start).
You need to figure out how to bias the input so instead of 0-4.11V, it’s +/- 2.055V, then you just need a gain of about 4.86 to get this to +/- 10V. Oh yeah, and you’ll need a +/- 12V or +/- 15V power supply (or DC-to-DC converter) for the op-amp…
Details are left as an exercise to the reader.
thank u very much for ur reply…
but how can i bias input to +/- 2.05v… i need to write any software program for that…
thank u …
No, not software. Resistors. I think you need to consider a different line of work if this is too hard to understand.
Go back to the differential amplifier circuit and see if you can determine R1, 2, 3, & 4 values such that
(V+)(R3/R1) = 10 and
4.11(R3 + R1)R4/(R4+R2)R1 = 20
That should get you what you need.