modified 5 years ago

Feedback Ammeter for Higher Currents

00:32:16

Typical feedback ammeters cannot measure above 20-30mA because the current actually flows through the op-amp and most op-amps can't handle much current.  This one has it's output buffered by a PNP transistor (I would make it a FET if EveryCircuit's FETs weren't so weird), allowing it to handle much higher currents.  It does still have limitations, the op-amp's output hits the power supply rail at a few hundred mA.

published 5 years ago

Ginikohn

5 years ago

Yes, the FETs in this app seem very strange to me also.

PrathikP

5 years ago

FETs I'm EC aren't wierd. The just have to be setup correctly. Refer to the MOSFET library

PrathikP

5 years ago

http://everycircuit.com/circuit/5282567524450304

Awds95

5 years ago

@PrathikP I should have said they're defined weirdly, typically a FET is characterised by parameters like Vgs and Rdson, not substrate thicknesses. It's a bit like defining capacitors by plate area and distance, rather than just capacitance.

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