Dear Forum Members,

Introduction

My latest product "Weld Checker" has the features of measuring
1. Welding Current.
2. Conduction Angle.
3. Number of cycles in welding.

This is a hand held device "battery operated". This device takes input from a Rogowski coil and then does the above 3 measurements and displays on the LCD.


Problem
For better measurement accuracy, I use 3 Measurement ranges
1. 0kA-18kA Measurement Accuracy 0.1kA
2. 0kA-36kA Measurement Accuracy 0.2kA
3. 0kA-52kA Measurement Accuracy 0.3kA

I use a Op-Amp based Inverting amplifier for signal gain control. For range selection I simply change the feedback resistor of this amplifier and then do the necessary multiplication in software. Due to this for range selection everytime a jumper has to be moved and the range selection button is to pressed for informing software about this [ For necessary multiplication ].

I want to simplify this two step range selection by using a single step that is just by pressing the range button. That means I am looking for some alternative so that the Feedback resistor selection instead of jumper can be made automatic. What are the options available for this. Looking forward for your kind suggestions. If the above information is insufficient / confusing kindly do let me know. I will furnish any kind of required information.

Thanks & Regards,
Prahlad Purohit