I've recently found the need for a ESR meter(My daughter and her boyfriend brought me 8 broken LED/LCD TVs and 6 have power problems).
I also decided to go all out and build a full blown ESR meter. The foundation for the meter is going to be the STM32F373 which has 3 16bit Sigma Delta ADC which are capable of simultaneous differential conversion. It also has DSP capabilities so I was going to use a DFT to determine impedance and go from there.
So I'll measure voltage across a test resistor, across the Cap under test and current. I want to use both variable voltage and frequency. I thought to use .2V to 1V for voltage and 100Hz to 25Khz for frequency. The test signal will be generated using one of the internal DACs filtered to a sine wave and buffered(for voltage and current control, including constant current(Edit to make it obvious)). I think I'll just output all this info via serial port and use a program to display and control. I can always add a interface later.
Sorry for all the leading information but I wanted make sure the question could be answered. With my brain though I've most likely forgotten something.
My question is under these circumstances which method of measuring current is better, using a shunt resistor or a current transformer. I've looked at a large assortment of various types of meters and just can't make up my mind.
I have a couple of IN Amps, a large assortment of op-amps and passive components available to me.