Hi,
I have posted a few questions about LTspice, and have several issues with simuations - all of which were due to my lack of understanding of the software and silly mistakes, I'm guessing this is no different. So I'm not complaining about LTspice at all, I'm just stumped and need someone to point out an obvious error in my simulation
Its a basic high-side current sense circuit. As I wanted two ranges, one to measure 0-1A, and one for 0-100mA, instead of changing the gain of the sense amplifier by 10 (which would also amplify offsets) I plan on using a mechanical switch to change the sense resistor from 0.1ohm to 1ohm - simple enough eh?
I've used voltage controlled switches as a crude way of simulating mechnical switches, just changing the voltage across the switch to turn it on/off. Simple, and very handy for switching things in and out of circuits - just using very low on resistance, and very high off resistance. Seems that if I short the switch with a wire/node in this simulation, it works fine. Short the other switch, works fine. But if I turn either switch on using a voltage source, no dice. Heres the schematic, and I've included a small zip file of the *.asc file, and the LM358.sub model file.
I'm pretty sure I'm msising something obvious, someone put me out my misery... as things like this bug me, even though its really just for academic purposes rather than a vital project.
Cheers!
I have posted a few questions about LTspice, and have several issues with simuations - all of which were due to my lack of understanding of the software and silly mistakes, I'm guessing this is no different. So I'm not complaining about LTspice at all, I'm just stumped and need someone to point out an obvious error in my simulation
Its a basic high-side current sense circuit. As I wanted two ranges, one to measure 0-1A, and one for 0-100mA, instead of changing the gain of the sense amplifier by 10 (which would also amplify offsets) I plan on using a mechanical switch to change the sense resistor from 0.1ohm to 1ohm - simple enough eh?
I've used voltage controlled switches as a crude way of simulating mechnical switches, just changing the voltage across the switch to turn it on/off. Simple, and very handy for switching things in and out of circuits - just using very low on resistance, and very high off resistance. Seems that if I short the switch with a wire/node in this simulation, it works fine. Short the other switch, works fine. But if I turn either switch on using a voltage source, no dice. Heres the schematic, and I've included a small zip file of the *.asc file, and the LM358.sub model file.
I'm pretty sure I'm msising something obvious, someone put me out my misery... as things like this bug me, even though its really just for academic purposes rather than a vital project.
Cheers!