Intresting - 20kHz Spikes from Capacitors

101

01:11:41

That could be a wave generator perhaps? 

published 10 years ago

WTFCircuit

10 years ago

The "spikes" are created by a bug in EC

hurz

10 years ago

WTF, tell us more about this "bug". Tell us the root cause and how to eliminate it, if you can.

WTFCircuit

10 years ago

Unfortunately I can't open the code of EC, you know how to do that hurz?

hurz

10 years ago

But you know its a bug? Explain in more detail, please.

WTFCircuit

10 years ago

I'm sure 80%. An ideal current source should supply a costant current, 10mA in this case and you confirm this using a resistor as a load, the current is constant. With the capacitor the current isn't constant any more. Also if you disconnect the capacitor, use a resistor as a loas and inject noise you will see a similar pattern in current flowing in the capacitor and, correct me if I'm wrong, but then current should decrease following an hyperbolic shape and not oschillate with an infinite frequency forever. So I deduced that this is a bug.

thebugger

10 years ago

The EC environment does have some noise. I recently made a circuit where i depicted it. Turns out EC has some -300dB noise that destabilizes the oscillators without shaking. Not really a bug but a rule of a sorts to bring the ideal environment closer to the real one.

WTFCircuit

10 years ago

So this is a glitch and not a bug...

hurz

10 years ago

Absolute correct BraveBuggzy! This is caused by numeric noise which is absolute normal for any computer simulation. From my experiences with EC I calculate this noise with about -120dB below e.g. 1V. So 1V ac would have less than 1uV numeric noise. This is much below a real voltage generator even if you have one for 10000bugs! BTW, thermal noise would be even higher. For me its also not a bug!

WTFCircuit

10 years ago

So in reality there is be this noise?

hurz

10 years ago

WTF, in reality there is much more noise but the cause is a different

thebugger

10 years ago

In reality noise may come from anywhere. Ground loops, semiconductor noise, thermal noise, RF noise, parasitic noise, inequalities of the components parameters (a multivibrator exploits the last) etc. There are so many noise factors I can hardly recite them all. EC also has some inherent noise, not as a bug, but to bring the ideal environment, in which nothing will ever oscillate without shaking, to a closer to the real environment.

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.