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|April ESR Tester, 100uA use 50uA meter||Jul 9th, 01:43||2||282||on 9/7/14|
|April ESR Tester, 100uA use 50uA meter||KB0MNM||on 9/7/14|
|Hi Zack & others at ARRL-
I was getting ready to try building the Capacitor ESR tester as detailed in April's QST magazine. Unfortunately, the local parts store had no 100uA meter movements. They did have one for 50uA.
So a repeat of how to determine the correct shunt resistor might save me a bit of effort.
I also noticed that QST later mentioned one error with respect to the pins 8 & 4 of the power to the TL082 op-amp ( one section only, the second one ). What they did not mention was that if you look at the magazine article the floating supply voltages are + and - 4.5 volts derived from the 9V battery. The other drawing ( downloaded with the PCB layout ) shows + and -9 V, very difficult to derive without a chip such as the ICL9660. I was really hoping for a line-powered rather than battery powered supply for this project.
An "Arduinio" hybrid would also be a great idea, but then if all wishes were granted some of us would fly without machines...
Thanks in advance- 73- KB0MNM Jon email@example.com