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The circuit on the left is using EC to describe switching. (Mosfet simulating a SPST switch).
The circuit on the right is using EC to describe amplification. (Mosfet simulating drain current control).
The LED in both cases look fairly similar, as do all of the visible similar settings, but....
Turn the resistor Ohms down, or the 9v supply up for each circuit...
On the left switching circuit.....the LED burns out...as expected with a switch.
Do the same with the right amplification circuit.....the LED holds at 20mA max. (or any desired current).
The amplification circuit on the right is not using the full 20mA current entirely for the LED...there is some power loss in the Mosfet....not good as a switch, but it is available to follow input signals on to a suitable fixed dc drain current.
The switching circuit on the left is full on..... a good switch, but no good for following input signals with its shifting dc drain current.
Can you see how the two circuits differ, and how to adjust them to your switching/amplification needs?
Can you see why the amplification mode on the right needs its resistor adjusting down to below 250 Ω to do the amplification job properly?
Wiggle the gate volts supply above/below the set 3V threshold in each circuit... see the different LED response. (best to highlight the resistors to see that) .... The amplifier mode is more ready for following input signals here at the gate in this way (with refinements). The switching mode shows full fast on/off.
When using a Mosfet in EC for switching, it is easy to adjust the settings ... as described here: http://everycircuit.com/circuit/6272290221457408 ... in the summary part there if you wish to cut a dash.
When using a Mosfet in EC for amplification then a deeper understanding of the Mosfet settings is needed....ask as reqd. ... I will try and help if I can.
The EC default Mosfet only allows a max. of 8.76mA through the LED in the above schematic arrangement because the default EC Mosfet is not set for full switching simulation.
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