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Differential Amplifiers Made Easy

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  • čas přidán 10. 08. 2021
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    / theaudiophool
    Differential Amplifiers are one of those circuits that can look a bit scary. But we will see today that if you look at it the right way, a diff amp is really no more complicated than the humble common-emitter amplifier!
    By understanding how a differential amplifier works, we will be ready to really delve deep into operational amplifiers (op-amps). The core component of an op-amp being a differential amplifier at its input!

Komentáře • 64

  • @shreeyadave6679
    @shreeyadave6679 Před rokem +29

    Finally someone was able to explain it. I am not even exaggerating but i literally had tears in my eyes mid through the video because finally I am understanding the concept.❤️❤️

  • @prestonmno4180
    @prestonmno4180 Před rokem +1

    Your channel is a godsend. I'm in my 3rd year of EE and your content is finally linking everything I have learned with building audio electronics. Which has always been my main goal. TY!

  • @samhughes1747
    @samhughes1747 Před 2 lety +7

    Dude. I seriously appreciate your energy. This actually explained a couple circuit schematics I've seen, that I was kind of just taking on faith. Solid! You also walk a really pleasant line between approximation and reality that I find distinctly helpful.

    • @TheAudioPhool
      @TheAudioPhool  Před 2 lety +1

      "Walking the pleasant line between approximation and reality" should be my channel tagline or something! Love it! Haha :)
      Thanks for watching!!

    • @DollysplitBand
      @DollysplitBand Před 2 lety

      @@TheAudioPhool Love it, and the tutorials. This is phenominal work! I would love to see you go into some details about active loads, current mirrors and V to Current conversion.

  • @bas1cbas1c
    @bas1cbas1c Před 2 lety +3

    You're explanations are incredibly clear - much more so than any other source i've found

  • @queuerious
    @queuerious Před 8 měsíci +2

    Quite excellent insights and appraoch to explain the comparator circuit. It appears in an old power supply voltage control circuit (Coutant LQT 100) and your video is helping me digest and understand how it works to repair it.

  • @vinnyp2115
    @vinnyp2115 Před 2 lety +1

    Finally, a tutorial on Diff Amps from someone I can understand! Well done brother!

  • @randomroughneck1030
    @randomroughneck1030 Před 2 lety +5

    Just found this channel, absolute treasure trove of information! Thank you!

  • @jj74qformerlyjailbreak3
    @jj74qformerlyjailbreak3 Před 2 lety +3

    Great walk through explanations. I’m sure at this rate I’ll have a decent synth by summer. Glad I met you mate.
    God Bless.

  • @orfeassiozos1575
    @orfeassiozos1575 Před rokem

    Hi from 12:52 and hi from me, an electrical engineering student 3 days before my exam in Electronics II. Thank you so much for this video!

  • @JKEYSONVINYL
    @JKEYSONVINYL Před 10 měsíci +1

    thanks to your massively helpful videos along with some extra googling, i have been able to design my own tape saturation box with a discrete opamp output thank you so much.

  • @iamsparkicus
    @iamsparkicus Před 2 lety +1

    Had to watch it a couple of times but I finally got it. Eureka! Fantastic teacher.
    Thanks for uploading.

  • @108.LordShivaYT
    @108.LordShivaYT Před 4 měsíci +2

    You deserve more Subs!

  • @oakspines7171
    @oakspines7171 Před rokem +1

    Yes ,the best way to illustrate and for people to learn something. You are genius. Another similar concept that even many experienced engineers still get confused and not understand is Gain and Phase margins. Similar illustration like it here would show it lucidly and clear the myth. Some calculation would be needed to zoom into where the frequency or the capacitive loads may cause oscillation. Many still doo not know what a signal oscillation looks lie, unfortunately. Thanks.

  • @germas369
    @germas369 Před rokem

    Thank you so much. I come to watch your videos to refresh my memory since I had forgotten a lot after university. Your explanations are very clear

  • @ninad2740
    @ninad2740 Před 10 měsíci

    amazing video thanks a lot

  • @queuerious
    @queuerious Před 8 měsíci

    The more I think about your analysis of input signals : you imply that for any two input signals of whatever shape they take, they can be decomposed into 1) sine waves in phase, same amplitude (the common mode content in the pair) and 2) sine waves 180 deg out of phase (what makes the input pair differ)...which uses the idea that any signal is a (complex) sum of sinewaves, and any phase shift is constructed from 0 and 180 phase sines with varying amplitudes? Sorry for the basic thinking here, but I find your tutorials very helpful to tease out my understanding!

  • @faisletoismeme
    @faisletoismeme Před 11 měsíci

    Thanks for sharing your knowledge. I love the way you explain this.

  • @MrAlFuture
    @MrAlFuture Před 3 lety +1

    This is such a good explanation. Thank you!

  • @cougar1861
    @cougar1861 Před 3 lety +1

    As promised! Nicely done. Til next time.

  • @robr8554
    @robr8554 Před rokem +3

    When you ground the base of the transistor wouldn't it be off? How does the collector of the off transistor produce signal?

  • @dr.frankenstrat2076
    @dr.frankenstrat2076 Před rokem

    You are a really good teacher-- i am a guitar amp guy-- and have been looking for "long tail pair info"-- found it with your lesson thank you-

  • @ashutoshramarathnam1445

    WoW this is a GEM literally...thank you so much will never forget this bro!

  • @dar_kkk
    @dar_kkk Před rokem

    thank you very much for such a great explanation! i finally got it

  • @Ganjalf_the_Green
    @Ganjalf_the_Green Před 14 dny

    Tyabk you for the amazing explanation. If i understand correctly, then, the reason why we often use a current mirror as a tail current generator, instead of a resistor with fixed potentials, is that the current mirror will *ideally* feature a very high output impedance, thus since this is featured at the denominator of the common mode gain, this means that the common mode gain will be hugely reduced?

  • @aspiredifferent8085
    @aspiredifferent8085 Před 2 lety +1

    Thanks a lot Buddy!!!

  • @erin19030
    @erin19030 Před rokem

    This will be the first circuit experiment on my new basic research bench when I get it built. I am interested in how these magical little pieces of rock amplify signals.

  • @duality4y
    @duality4y Před 2 lety +1

    I just subscribed this channel is awesome.

  • @Cracked_and_Crunchy
    @Cracked_and_Crunchy Před 2 lety

    great work dude!

  • @swaritmahalsekar5521
    @swaritmahalsekar5521 Před rokem

    Very nicely explained ❤

  • @joaovictorborges4610
    @joaovictorborges4610 Před 2 lety +1

    very good

  • @ricomajestic
    @ricomajestic Před 2 lety +1

    Excellent video! I now fully understand how these differential amplifiers work.

    • @incxxxx
      @incxxxx Před 2 lety

      It only sems to you. Try to do experiment and you see that this is only illusion.

  • @fanir33
    @fanir33 Před 2 lety

    Great video! Helps a lot!

  • @Bianchi77
    @Bianchi77 Před rokem +1

    Nice video, thank you for sharing it :)

  • @olvyshh147
    @olvyshh147 Před rokem

    Key to understanding:
    Remark :
    Transistors are connected according to the common emitter circuit, in the OE circuit, the voltage at the emitter, roughly speaking, is always equal to the base voltage.
    Since the potential at the point of connection of the emitters MUST be the same for both transistors, someone must give in ....
    This small voltage difference falls directly on the PN junction of another transistor, closing it, that is, roughly speaking, if we assume that the transistor is open when the voltage across the BE is 0.7V, then with a voltage difference of 0.1V, we have a voltage drop on the other transistor on the BE 0.6V is not a completely open transition !!! This is equivalent to the fact that we stupidly applied 0.6V to the base. What will be the base current at this voltage?? Look at the CVC of the diode, the current will be almost absent, so the author talks about Eberton Moll's formula.
    You can see the CVC of the diode, what current the LED will give out if its PN junction is not fully open, that is, if it is open at 2.7V, apply 2.6V to its legs and you will see that the current almost does not flow. So here, increasing the difference
    Like this comment if it was useful for you so that others can see it.

  • @H3nryl4v3ry
    @H3nryl4v3ry Před 18 dny

    I've got two questions. 1. Can I use this differential amplifier in parallel with a load.
    2. Do I need to impedance match the differential amplifier to the load impedance

  • @henoknigatu7121
    @henoknigatu7121 Před rokem

    Hi can you make video on how one port and two port network synthesis applied practically on designing ckts like filters and amplifiers, thank you.

  • @enverkocaman3699
    @enverkocaman3699 Před 2 lety

    Great video. I love it.

  • @erin19030
    @erin19030 Před rokem

    I remember the differential amplifier was made of tubes, called a Phil-brick Amplifier.

  • @fayeSHeg
    @fayeSHeg Před 10 měsíci

    thank I understand

  • @t1d100
    @t1d100 Před 2 lety

    Good stuff.

  • @martindowney7915
    @martindowney7915 Před 2 lety

    I wont lie my head is a bit spinny on that 1 mate,,love ur work tho pal,thanks.

  • @burakg7246
    @burakg7246 Před 9 měsíci

    And you can explain it just like that.

  • @nantes9807
    @nantes9807 Před rokem

    how to build differtial amplifiers without negative source ?

  • @vladimirfrolov1440
    @vladimirfrolov1440 Před rokem

    @The AudioPhool Is there a chip simular to CA3046 but with pnp transistors? Thank you.

  • @duality4y
    @duality4y Před 2 lety +2

    so where is the next video ? next week has been a month ago :D (just excited is all)

    • @TheAudioPhool
      @TheAudioPhool  Před 2 lety +1

      Haha! It's up now mate.
      Really sorry about that, i had the video done but had to go away for a little while so i put it up on my patreon about 2/3 weeks aho but i couldn't release it fully without schematics and things!

    • @duality4y
      @duality4y Před 2 lety +2

      @@TheAudioPhool dont worry, was excited and really love the videos :)

    • @TheAudioPhool
      @TheAudioPhool  Před 2 lety +1

      @@duality4y Loving the enthusiasm!! :)
      Thanks for watching!

  • @ngocnguyenhong1956
    @ngocnguyenhong1956 Před 2 lety

    Why you did not multiply the denominator by 2 in the G_common as in the G_diff ?

  • @jakep8484
    @jakep8484 Před rokem

    So basically I could just calculate a common emitter amp and then mirror it with a matched transistor and use a ccs for Rx?

  • @audiodiwhy2195
    @audiodiwhy2195 Před rokem

    Thanks for the vids. very imformative! I have a question.....I have watched this video a few times, and still I am not sure I can follow what you say at 6:26. You are saying a "loop" (I assume, current) is going from the transistor on the left, through the 2 resistors, through the transistor on the right, and to ground. That's where I get stuck--I didn't think current could reverse bias through a transistor as you describe--on a NPN, the base > emitter appears to the world as a diode. But then again--I am a newbie....Do I have a fundamental misunderstanding of current flow through a transistor?

    • @TheAudioPhool
      @TheAudioPhool  Před rokem

      You're not wrong! The only thing missing from your understanding is the assumption that the transistors are on all the time, when the transistor is switched on we can think of the base->emitter junction as more like a very low value resistor, allowing the input to be placed 'across' both transistor's emitter resistors. When i say loop i mean a voltage loop in terms of kirchoff's voltage law. I think i mention this in my circuits 101 video :)

  • @BryanDenham
    @BryanDenham Před 2 lety

    im new to building DIY guitar FX pedals . i recently built a (Boss BD-2) Blues Driver ,it uses a discrete opamp for two stages in the circuit. i really like how the circuit sounds but i would like to understand how the discrete opamp works a bit better . im a bit confused on how the negative feedback works and how the audio signal flows through the discrete opamp ,I was wondering if you have the free time could you make a short video showing how the audio signal flows through and how the negative feedback works using the Boss BD-2 schematic . thank you for the videos i enjoy them a lot.

  • @youliantroyanov2941
    @youliantroyanov2941 Před rokem

    U da man 👍

  • @chandrakumargurung7034

    Are u electronic engineer

  • @kfcmcdonalds
    @kfcmcdonalds Před 2 lety

    Proper english accent ... a white guy talking electronics, atlast :) ...keep it going man !

  • @attilarivera
    @attilarivera Před 2 lety

    Won't it work as a stereo amplifier then?
    Oh well
    🤢

  • @codyfan1097
    @codyfan1097 Před rokem

    Thank you for the videos🥲

  • @drstrangelove09
    @drstrangelove09 Před 2 lety

    maths