I realize I have an extra opamp unused in this Quad OpAmp package used in my DIY Electronic Load. So maybe we should utilize that somehow. Using a 0.1-ohm, 1% resistor as a current sense, we can minimize the voltage drop and power dissipation across our resistor. Things run cooler. But now the voltage reading across our current sense resistor is just 1/10th before. Whereas with a 1-ohm resistor, we have the relationship of 1mV voltage drop is equivalent to 1mA current flowing through it. Now, it’s 0.1mV voltage drop for every 1mA of current. Here’s where we can utilize our extra opamp by wiring it as a 10X voltage amplifier. And if we include a trimmer resistor, we can even calibrate it. Of course, the opamp I’m using, an LM324, isn’t a high quality chip, and it’s offset voltage can be a few millivolts, which multiplied by a gain of 10 becomes tens of millivolts (which translates to milliamps) of error reading. Somewhere down the road I’ll redesign this Electronic Load PCB and incorporate all these changes/improvements. The photos shows the actual current and the measured voltage drop across the 0.1 ohm resistor, after multiplying it 10x using the opamp wired as a non-inverting amplifier. #electronicload #current #power #currentsense #highside #opamp #amplifier #electronics #electronicsdesign #electronicsengineer #electronicsengineering #engineering #testequipment #workbench #basicelectronics #noninvertingamp #basicelectronics #testequipment
