The Class A amplifier - build and test (2/2)

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  • Опубліковано 24 гру 2024

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  • @carmelpule8493
    @carmelpule8493 Рік тому +8

    Brilliant presentation. I have experience with all the circuits presented as I started this work in 1952, but I must say I am really enjoying how this gentleman is covering all the detail. Well done, for not only including the theoretical part , but also the simulation, the implementation practical part, and testing and other detail only an expertised person can depict, .

  • @nelgau
    @nelgau 2 роки тому +39

    Each and every one of your videos is a masterpiece of exposition. Thank you for being so generous with your time and for teaching us electronics! :)

  • @yoavrosenbach
    @yoavrosenbach 2 роки тому +11

    AMAZING !!!! This is how it should be thought !!!!
    I don't understand where are your other 1M subscribers...

  • @RicardoPenders
    @RicardoPenders 2 роки тому +3

    You are a great teacher in electronics, I like that you are showing every detail you need to take into account when designing a circuit and you also show what the circuit does with the change of temperature, what the current consumption is when there's a signal going through and without a signal, I didn't know that the temperature would go up without the signal.
    So you can see that you excellent way of explaining things and showing the signals on the different meters and scopes that even someone like me who knows almost all you need to know can still learn a thing or two from watching your videos.
    Thank you very much for sharing this online, you make it so easy to follow along and you keep it interesting so I don't lose focus.

    • @alexlo7708
      @alexlo7708 Рік тому

      Input signal made transistor changes its own resistant value which it goes in a unidirectional way , rises up from DC quiescent operating point. The more resistant ,the less current can flow in and the less power loss.

  • @tlmoller
    @tlmoller 2 роки тому +11

    “How hard can it be?”. Love these videos. So great in all ways.

  • @librasulus
    @librasulus 11 місяців тому +1

    I am too ignorant in the field to understand even the half of your content but I salute you, great content!

  • @rhp9797
    @rhp9797 2 роки тому +3

    I loved the tease at the end! Absolutely brilliant!

  • @alexloktionoff6833
    @alexloktionoff6833 2 місяці тому +1

    How to calculate and find the best inductance for class A amplifier? Especially if use toroid /* to avoid interference !*/, and a transformer on toroid ! Do you have. video for it?

  • @andromedusmoat9608
    @andromedusmoat9608 2 роки тому +3

    Fast becoming my most watched channel... Keep it up!

  • @sureshlala6462
    @sureshlala6462 Рік тому +1

    Thanks, very educational for me to understand as I build Class A amplifiers, always nice to see if I am doing anything wrong, very well explained, cheers.

  • @geoelectronica
    @geoelectronica 2 роки тому +1

    Super tare Maestre, congratulation!
    Ai putea sa continui seria cu si despre amplificatoare, sunt multi pasionati, e un subiect care prinde.
    Exp de topicuri: the most common amplifier classes, Boucherot cell, Totem Pole, Bootstrap Circuit, LONG TAILED PAIR, constant current stage, current mirror circuit, Voltage Amplification Stage, Complementary-Feedback-Pair, single ended amplifier, etc.
    Cheers

  • @curtstacy779
    @curtstacy779 2 роки тому +3

    Excellent video again. I love the way you explain things.

  • @BIGRIP87
    @BIGRIP87 2 роки тому +2

    can i use iron core inductor for audio application?
    because at lower frequencies the ferrite core inductor, won't act more like an inductor.
    right?

    • @FesZElectronics
      @FesZElectronics  2 роки тому +2

      In general iron core is most common for low frequency (

    • @BIGRIP87
      @BIGRIP87 2 роки тому

      @@FesZElectronics right.

  • @Flightsimer96
    @Flightsimer96 2 роки тому

    4:05 : Why is the max current through the emitter resistor equal to the peak current through the load resistor?

  • @sheepbaba
    @sheepbaba 2 роки тому +2

    Nice one and thanks.
    I recently built a Class A audio amplifier kit. I just followed instructions and don't really understand how it works. This video helps. It sounds amazing. Running about 15wpc it is not too hot but has huge heat sinks and uses a current source transistor.
    The inductor design looks cool but am intrigued by the transformer coupling.
    Previously I have been using a SET valve(tube) amplifier.
    I can't wait to see if you find a way to make it more efficient.

    • @FesZElectronics
      @FesZElectronics  2 роки тому +2

      I'm happy you liked the video! I guess that with the valve amplifier you had the transformer on the output - so that should work more efficiently than the transistor amplifier with current sinks. However, with valves, the minimum anode voltage that you can achieve is limited - you cannot go as low as with transistors. I guess the best of both worlds would be a transistor amplifier with a transformer output - this is not that common since the price of the transformer is way more than the extra current sink transistor + heat sink.

    • @sheepbaba
      @sheepbaba 2 роки тому +1

      @@FesZElectronics that's really interesting. The guy who made the valve amp I believe also made some transformer coupled transistor amps.
      Now I know why... 😊
      Sadly he passed away last year. He used to make stuff for studios and even Pink Floyd.

  • @BIGRIP87
    @BIGRIP87 2 роки тому +6

    next letter after A is B

  • @urlkrueger
    @urlkrueger 2 роки тому +1

    Well, let me help you out. B comes next but is then followed by C and then somewhere down the list is PP.
    What I like about your channel is that I am learning how to change my thinking from a technician's point of view ( how does this work ) to an engineering point of view ( how do I make something that will work).

    • @FesZElectronics
      @FesZElectronics  2 роки тому +1

      PP (push-pull) is not an operating class, its just a specific implementation having active elements both "pull" and "push" the output - you can even implement class A operation with a PP stage - low side amplifier transistor and high side constant current source. Unless of course you meant something else by "PP".
      I'm happy you are enjoying my videos :D

  • @rubenhidalgocarrillo
    @rubenhidalgocarrillo 2 роки тому +4

    Very good video, as always. Thanks!!!

  • @marctamtonthat
    @marctamtonthat 2 роки тому

    Thank you for your great videos. Very interesting and useful.
    Some DC circuits are designed to reverse the polarity every minutes in order to mitigate the wear of the filament. It would be interesting to have this feature.

  • @rogeronslow1498
    @rogeronslow1498 2 роки тому +6

    Try doing a two-tone test. That's the acid test of linearity.

    • @alexloktionoff6833
      @alexloktionoff6833 2 роки тому +2

      i.e. intermodulation, two hi-frequency tones with 1KHz difference

    • @FesZElectronics
      @FesZElectronics  2 роки тому +2

      I will try this out for the next amplifier - stay tuned for Class B :D

  • @acestudioscouk-Ace-G0ACE
    @acestudioscouk-Ace-G0ACE 2 роки тому +2

    A lot of useful information, thanks.

  • @objection_your_honor
    @objection_your_honor 2 роки тому +1

    Can a power FET be used in linear mode, in place of the NPN?
    since it's a voltage driven gate, can bigger resistors be used in biasing the gate, to decrease power loss?

    • @FesZElectronics
      @FesZElectronics  2 роки тому +2

      Yes, FET's can be used, and since they don't need current for the static operating point, it will allow the use of larger values. The only thing to keep in mind is that the exact threshold voltage for the FET is contained in quite a wide range (its not as precise as the 0.6V for the BJT); so you might need to adjust the bias resistors with a potentiometer.

  • @dannyperry8070
    @dannyperry8070 Рік тому +1

    Great video. Why did you not place a bypass capacitor across RE? Also why is the supply voltage 1/2 of Vload p_p? is that because of the inductor?

    • @FesZElectronics
      @FesZElectronics  Рік тому +1

      By placing a capacitor over RE, you get a very high amount of gain which is highly temperature and transistor dependent. I kept it this way to have a more predictable value. When amplifying small signals, you want as much gain as possible, so you will use the capacitor, but for large signals, too much gain will cause distortion.
      Regarding the second point, yes, the inductor is allowing a higher collector voltage than the supply, so by using inductors you can get higher output voltages.

  • @dannyperry8070
    @dannyperry8070 Рік тому

    I have tried a similar circuit to yours. What I find that without the 50 ohm load the gain varies with frequency because the impedance of L increases. With a 50 ohm load there is also some variation in gain. The larger the load resistor is the greater the variation.

  • @pu5epx
    @pu5epx Рік тому

    Audiophiles will love this!

  • @dannyperry8070
    @dannyperry8070 Рік тому

    In calculating the static current, you are using RL 50 ohm load which is blocked from Vcc via capacitor. So I don't understand how this can be used to provide the static current. The way I see it is the static current is provided through the inductor which under DC conditions would have very little resistance and with a signal its resistance changes till RL become dominant. I really like your videos and using them to design and experiment with similar circuits.

  • @sahebdarkhor
    @sahebdarkhor 8 місяців тому

    Hi what is difference between video amplifier and audio amplifier in equal circuit?

  • @stefanb.933
    @stefanb.933 Рік тому

    hello, how can an 8hz sine wave be played on a 4 ohm load?...it doesn't have to be amplified...

  • @persiangulf2282
    @persiangulf2282 9 місяців тому

    Hi bro
    I have a question
    How we should delete dc ofset from output of class a amplifier who push speaker diaphragm out?
    Please help me
    Tnx 🙏

    • @FesZElectronics
      @FesZElectronics  9 місяців тому

      The easy way is to add a series capacitor of large enough value so that the useful signal is not attenuated.

  • @alexloktionoff6833
    @alexloktionoff6833 2 місяці тому

    But you can loose less even for low voltage class A amplifiers with MOSFTETs. Do you plan a video about it?

  • @dannyperry8070
    @dannyperry8070 Рік тому +1

    Trying to understand why the DC resistance of the inductor was not taken into consideration?

    • @FesZElectronics
      @FesZElectronics  Рік тому +1

      I guess I skipped that just to simplify the analysis. For more accuracy that should also be considered.

  • @JacquesConradie
    @JacquesConradie 2 роки тому +1

    Very informative and well explained - thanks!

  • @smak201
    @smak201 2 роки тому

    Excellent video as usual! Have you considered also analyzing the noise of the amplifiers and how they work with very weak input? It would be interesting to see how different topologies and transistors (BJT, JFET) compare when there is no need to produce much power, but the input signal has very low amplitude.

    • @FesZElectronics
      @FesZElectronics  2 роки тому +1

      I guess this a different topic - typical noise figure of different component types; its an interesting topic though, I will try to do something about it at some point!

  • @piclife1178
    @piclife1178 2 роки тому

    Great video. Did you try bypassing the emitter resistor with a capacitor to maintain DC operating bias but increase AC gain. BD135 give great RF performance up to 10Mhz in class C but usually end up going pop because of the high collector voltages produced.

  • @tahanprahara
    @tahanprahara Рік тому

    Hello... how to choose the right inductor size? thankyou Sir

  • @quantumdirac
    @quantumdirac 2 роки тому

    May create electronics course and sell on Udemy. I believe it will be quite popular. I will be the first one to enrol.

  • @ladronsiman1471
    @ladronsiman1471 Рік тому

    Are this calculations also similar for a fet transistor ?

  • @marekwafel8651
    @marekwafel8651 2 роки тому +1

    👍

  • @bsuryasaradhi6816
    @bsuryasaradhi6816 2 роки тому +1

    gold!

  • @R2AUK
    @R2AUK 2 роки тому +1

    ❤️👍

  • @shams350z
    @shams350z 2 роки тому

    Hey man, hope you're doing well. You look stressed out.

  • @SheikhN-bible-syndrome
    @SheikhN-bible-syndrome 2 роки тому

    Your low in iron and it wouldn't hurt to add some more magnesium and potassium into your diet via supplements ... Just fyi