Current source

200

03:36:24

A simple current source can be created from a voltage source and resistor so long as values are much higher (an order of magnitude) than the output circuit.

Note how the values of the voltage source and resistor are much higher than the resistance of the potentiometer. Run the simulation and adjust the potentiometer's wiper position - the current never varies more than 0.1% (0.1uA). The high values of the current source make the potentiometer's value irrelevant, because I = V / (R + Rload)

published 9 years ago

jass1989

9 years ago

Your first resistor is eliminating all the current that the POT even has to see. Plus your pot is so small in comparison it has nothing to do.... In real life your pot would blow up first...

WTFCircuit

9 years ago

Other than that a resistor is one of the worst current sources because it's highly load dependent

hurz

9 years ago

@johntron, good example for a current source, even if the values are a little extreme ;-) ! Keep it up please!!

johntron

9 years ago

Yes, I'm aware this is unrealistic - it's just to demonstrate a point. I'll update the description - thanks!

hurz

9 years ago

NoNo, don't update the description. I think 100kV is a little extreme and could be 100V. Most users don't understand there is no difference in real voltage vs current source. I like this example. Even if most users, as you can see from previews comments, do not understand.

johntron

9 years ago

hurz, yeah, I guess you're right. Cool - thanks!

hurz

9 years ago

You are welcome!

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