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error in rb calc?

RR
Intellectual 275 points

hello,

pretty new to transistors! i was just wondering how the fellow in the following video got 360k for Rb????

please view 07:00 of 10:08 of the following video

http://www.youtube.com/watch?v=Pqm5-axy7m8

I have done the math forwards and backwards and i don't seem to come out to this value....???

just wondering if its a mistake in the video.

thanks

  • 0
    TI__Expert 7925 points

    Hello, RR. You are correct that if we follow the video's math, (6.65 – 4.03) * 160 / 10–3 = 419200, which is not 360000 as the video wants it to be. (And really, 3.3 + 0.7 = 4.0, so I don't know how he got 4.03. Margin of error?) If we type in 4.4 instead of 4.03, the math produces 360000. It's likely that this video lecturer just did a small calculator error. I've done that plenty of times, and still managed to get a good job. : )

    If you're pretty new to transistors, there are resources available to help you. We deal with specifically many-transistor audio amplifiers on this forum, so it's not the first place you should turn to. If you're a university student, take some time with your professor's office hours to discuss what doesn't make sense to you. The Art of Electronics is a fantastic introduction to real-world transistors, which is what we deal with on this forum. The Complete Electronics Self-Teaching Guide is a little more introductory but still good; you may like it. Finally, I recommend MAKE: Electronics and its associated kits for really learning electronics with your hands!

    Good luck!
    Matt