I dont know if it helps but i used a 1ma meter with the original design schem,i tried losts of component changes but found if i fed it 10v from 2x 5 volt buck converters with the outputs in series running from 2x 18650 batterys it worked fine,if i remember the dui test voltage was about 180 millivolt so still good for in circuit tessting,there is pics of it here its an old bradley multimeter case and movement i used.,the meter movement is 1 ma not 50 ua.