Maker Pro
Maker Pro

Ciruit idea and help


Aug 24, 2011
Aug 24, 2011
Dear All,

I have a sensor, which give me certain analog input, i display this input on a scale of 0-100 on LCD. it reads 100 for full scale input. this section is working perfectly fine.

Now further, i also need a repeater 4-20mA (0->4mA and 100->20mA) output so using a circuit according to this below link
I was successfully able to implement the repeater output part as well.

so its perfectly working fine in ideal case(when Sensor is not poison).

But, now i want to built a circuit wherein as the sensor starts to lose its sensitivity, i want to re-calibrate it(using keypads). the display section is working fine(after re-caribration)
but i cannot do the same with the repeater output. i have to use the zero and span pot for it.
I want to avoid these two trimpots after initial calibration and do it through program.

I'm using a pic-18f4520 for the same and CCS complier.

Please do suggest.