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Transistor Amplifier for the Beginner, the basics

Transistor Amplifier for the Beginner, the basics



Picture of circuit on breadboard 1.1MB
http://www.richardmcwhorter.com/NPN_PNP_AMP/DSCN2942.jpg
Transistor Amplifier for the Beginner the basics

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Tags: transistors

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21 Comments

  1. Date: December 2, 2016 at 17:05
    Author: dafl00

    noob question: at the end of video with two stage amp, if left amp is out of phase 180 and right amp is out 180 then why doesn't the final (green) signal show up as in phase with original signal generator? I thought it would keep shifting the time base of signal.

    thanks

  2. Date: December 2, 2016 at 20:15
    Author: Catalin

    Could you tell me what is the advantage on choosing and designing this BJT based amplifier (or whatever BJT based amplifier) over designing one with an OP amp ? Or, this is how it used to be done and nowadays is preferred OP amps ?

  3. Date: December 2, 2016 at 21:41
    Author: rodney garrett

    Nice video. I always learn watching your videos.
    Thanks for making your videos

  4. Date: December 3, 2016 at 00:49
    Author: n1chp

    Hi Rich, Thank you very much. Easy to understand.

  5. Date: December 3, 2016 at 02:25

    Great video. I hope you continue to do these basic circuit vids. Would also be really nice to see these set up on a breadboard to.
    Either way they are very enjoyable.

  6. Date: December 3, 2016 at 02:27
    Author: vibra64

    You stated that the 470 ohm resistor is for self bias and the 100K and 10K are for fixed bias. Does the transistor need both for bias? Can it operate normally with just fixed bias?

  7. Date: December 3, 2016 at 04:42
    Author: Enteraname

    Please do more of this type of Beginner basic videos, very informative, THANKS!!

  8. Date: December 3, 2016 at 08:52
    Author: abele ballestri

    beautiful tutorial lesson on how PNP and NPN transistors can be put in cascade together to get a very high amplification at the end of the cascade.thanks for the very special lesson. You should bring some more of the theoretical way to explain other amplification stages like the output stage of an amplifier for guitar, for example.thank you.

  9. Date: December 8, 2016 at 15:50
    Author: Chuck Legg

    One of the best tutorial on transistor amplification I have seen on YouTube. It is so clean and simple with fantastic narration. Just wonderful! Thanks for your efforts, much appreciated.

  10. Date: December 23, 2016 at 20:50
    Author: rockndancenroll

    Hello, this was a very nice video thanks. Does anybody know where I can find more info on what are the specific resistors for (self-bias, fixed bias) and why are some large/smaller than others? Thanks

  11. Date: December 30, 2016 at 00:41
    Author: Doug Spurell

    Nice video with a couple of comments.
    1. The gain of each stage is ~ 2, for a total gain of about 4. Is this what you measure on the breadboard?
    2. The small phase shift due to both 0.03 uF caps and Zin of each stage should account for the 2 stage input output being out of phase.
    3. For the 2 stages, the positive rail on the schematic is grounded to the – rail. For a single source, this would be disaster. Two separate supplies would work. I see on your breadboard that they share an ac ground through your 12 V, 100 mA source.
    Excellent circuit.

  12. Date: January 13, 2017 at 00:50
    Author: Pablo Pazos

    is there an ideal bias and capacitor values for a 9v input? I want to try amplifying a mic signal and I have a 9v battery. thanks!

  13. Date: January 14, 2017 at 02:46

    Great video as always!
    I wonder though, while both of these cascaded circuits are exactly identical, the amplitude is still at all greater throughout the second stage. This means more current draw on through the load. In practice, we see the transistors and passive biasing equipment increase in wattage, as we move up the stages.
    So my question is: Should we simply go for a larger transistor whenever our current (amplitude voltage times impedance of the load) exceeds what the transistor can tolerate, or should clipping be taken into account as well in this case?

    B.R.
    -Ragnar

  14. Date: February 6, 2017 at 01:27
    Author: rodney garrett

    how are you powering this circuit? I notice that on the pnp transistor the positive is grounded. I was bread boarding this circuit but had to stop because I didn't understand the power supply.
    Thanks

  15. Date: February 10, 2017 at 19:10
    Author: rodney garrett

    Sir,
    I was experimenting with this circuit and my sine wave coming out of the first stage was clipping on the top part of the wave. I was using a 1kh sine wave using the resistors in you diagram. My transistors were bc547 and bc557. Can you advise me as to what I can do to correct this.
    I am a novice .
    Thank you

  16. Date: October 16, 2017 at 17:14
    Author: James Blount

    Thank you for these videos. They are very helpful and very easy to understand sir.

  17. Date: August 30, 2018 at 13:05
    Author: sam bishop

    Do the two stages have to be npn then pnp (or switched around) or can two npns/pnps go next to each other?

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