Building an ESR Meter - 2nd Attempt

[electronwaster]

Hi,

I asked about 2 years ago about ESR meters (https://www.eevblog.com/forum/beginners/esr-meter/) - I was interested in changing a particular schematic I had found so that it didn't need a transformer. You all kindly helped, but it never did get built. 

I now have a renewed interest in building one of these meters. So I've been researching and learning, mostly from the ESR repository that kripton2035 kindly introduced me to ( http://kripton2035.free.fr/esr-repository.html ) - and I've found all sorts of methods of making these devices. The one that actually looked achievable for me to build was w2aew's design ( https://www.eevblog.com/forum/projects/what-about-home-made-%28esr%29-meter/msg70878/#msg70878 ).

I tried to build it up on a breadboard, and quickly ran into difficulties. My hex inverter, opamps and meter weren't quite the same and I could only get it to half work. I ended up dismantling it and starting again. Yes - I should have tried to debug it or ask for help debugging it.

Call me mad, but I have since been clumsily trying to come up with my own design, based on sections of other people's circuits, but to suit the parts I have. I have built a simulation in LTSpice, just because that's faster to experiment with. I plan to breadboard it as soon as I have solved a problem I have.

I have attached a screenshot of a current reading for the 'meter' (modelled as a resistor), and the schematic too. If I could figure out how to low pass filter this so that I get a smooth line between those peaks, that would be great, but I have so far failed to get that to work. How would you guys design a filter to provide a smooth non-pulsed DC output?

Also - if you can suggest any other improvements before I build this in real life, I'm all ears! 

Cheers,
electronwaster (Still a complete novice!)