And it would be in parallel anyway, so it should add to the net circuit capacitance. The probe tip capacitance should be insignificant at ~10pF. At 5500 the effective capacitance is the same 53% of the measured capacitance. (could be some kind of x/x+y thing though.) But visually the resonance is around 5500, not 5000 (the scope is picking up a noisy peak). By the scope auto measurement it shifts but not by a linear proportional amount. In the second trace, I added ~100nF of capacitance in parallel. The effective capacitance is 53% of the measured capacitance. The resonance frequency shifted quite a lot. In the first trace, I have the same L & C but in parallel. I hope this is encouraging to anyone else getting started on LC resonant circuits!ĭidn't work out so well in parallel. As a first go at it, I felt I wanted the borders to verify correctness. I also should use all 10 horizontal divisions instead of 8. Also I should offset the display to see only the top half of the wave.
#CREATING PLOTS IN MACSPICE MANUAL#
That way it's easy to use the scope auto cursors to find the resonant point instead of all the zooming and manual manipulation I had to do. To do it more thoroughly, I think I should configure it as a parallel circuit, that way the current is minimized and the voltage is maximized at resonance.
#CREATING PLOTS IN MACSPICE SERIES#
Ultimately I will build this parallel but the resonance is the same so I just left the series configuration in place to do the "bode plot". That's not possible as a parallel circuit.
I did it as a series circuit because prior to this, I was looking at the individual L and C as individual components in the LC circuit, to see their individual contribution to the overall circuit.
Next I'll play with series and parallel resistance to see the effect on Q. The Q looks pretty low to me but I don't have a really good intuition about that yet. Maybe if I turn on the FFT channel I'll effectively get that. I wish there were a way to display the vertical scale log instead of linear. I'm amazed how close to theoretical the result is. Read a bunch of web pages, watched w2aew #54 #55 #56 (all 3 re: L and C resonance), watched Dave's #396 (use scope to create bode plot), ran the theoretical numbers and built a circuit on breadboard.
0 kommentar(er)
