Electronics > Beginners
Low cost, low power battery led indication cirucit
TerminalJack505:
I played around with my circuit in the simulator some more. I changed the amp and swapped the TL431 with a high-beta NPN transistor.
I tried to do as Vovk_Z suggested but didn't have any luck. My feeling is that you would need a fairly exotic op amp to do that. Either that or make the sense resistor much bigger. I completely nulled-out the offset voltage on a OPA197 (the amp used in my circuit) and the results were a good deal worse than my circuit.
The configuration used in my circuit (with the MOSFET) was designed for high-side sensing by people that are much smarter than myself.
Edit: Had a misprint in the attached image. The offset voltages in the diagram were listed as mV but are uV.
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