modified 7 years ago

Can you guess where the feedback is

01:02:26

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published 8 years ago

FernandoCPF

8 years ago

Its a bug

FernandoCPF

8 years ago

100mhz to 60hz no pasa nada

hurz

8 years ago

Its not a bug, its the "miller capacitance". This is a capacitor which is present from collector to base ( EC default is 5pF) but the cool thing, the forward beta does impact its virtual size. Put from base to ground an additional cap e.g. 10nF does shorts this effect and oscillation stops. Hope this helps.

jason9

8 years ago

Correct! Miller capacitance provides the feedback. That's the only explanation for the changing current into the collector of the transistor. Also, @FernandoCPF, you have to keep your mHz and MHz separate, because one mHz (millihertz) is 0.001 Hz, and one MHz (megahertz) is 100,000 Hz. That's a difference of nine orders of magnitude!

jason9

8 years ago

Actually, one MHz is 100,000,000 Hz, which means a difference of 12 orders of magnitude.

hurz

8 years ago

1,000,000

hurz

8 years ago

👍

jason9

8 years ago

Oh, yeah, 1,000,000. I was thinking of the 100MHz that this circuit was operating at.

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