This was built long ago upon acquiring a 20 microamp meter, to take advantage of reduced circuit loading compared to an existing multimeter with a 50 microamp sensitivity. The downside is a greater voltae drop of 200 millivolts in measuring current.
The temperature measurement uses a thermister probe,
The extra components by the meter are for a jack on the back which is intended to connect with the Scientech Meter, but care must be taken to avoid ground loops.
The AC accuracy is not very good.