Topic 37: Class B and AB Power Amps and Current Mirror Biasing
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- Опубликовано: 16 апр 2024
- In this video we derive the equations for gain, input resistance, output resistance, output power and transistor power dissipation for class-B and class-AB biased power amplifiers. The analysis of the basic current mirror is also analyzed.
You should make this series of blogs into a book and put it on sale for people interested in learning electronics.
Excellent video! An entire semester of Electronic Engineering summarized! - key - Q Point, biasing, Class A, Class B, AB amps, Emitter Follower, basic current mirror, Push pull, Importance of C2 - Coupling, energy to Q2 circuit when Q1 is shutoff, Crossover dissipaition, Bipolar supply ..
Thanks. There are a lot of videos on here by people that really understand how this stuff works but not many of them do a very good job of explaining or articulating their thoughts. I try to be precise and efficient with my explanations and work a sufficient number of example problems. 👍🏻
thank you, great content again. I am very happy i came across you somehow on the endless youtube. Also very appreciate the high quality of English language you use on your lectures. it's important for people form non English-speaking world. Thank you for your efforts!
Thank you! I try to be as precise and technically accurate as possible, without being too dry or boring. Not the easiest thing to do sometimes lol. Thanks again 👍🏻
@@Electronics4Guitar i have just received paper version of your lectures. i must say that buying books I have to be sure it will not end up on the shelf covering by dust. It took me a bit time, but yes I have it. That's going to be a good combination to read, listen and watch. I can imagine it takes a lot of time to prepare the content presented on youtube, hopefully you will not get tired 😊. Thank you!
@@robbor2204 thanks! I’m covering a lot more basic circuit theory in the videos. The publisher didn’t want the book to be over 1000 pages or I would have done that. I’ll get to all the topics in the book here, eventually 👍🏻
Very Good！Thanks！
EXCELLENT PRESENTATION!HOW DO YOU DETERMINE r'e?IS r'e ALWAYS .1 OHMS FOR LARGE SIGNAL?
@@davidluther3955 these large signal r’e values are just rule of thumb approximations.
I have a question...Voltage on emmiter always follows voltage at base... That mean when base voltage increase so also emitter just only by 0.7v less..when voltage at base decrease so does the emmitter...So how is the transistor become off?? Since the voltage difference between emmitter and base is always 0.7....how how?
27:34, i made such circuit in simulator a put a static voltage on the input, the reason is to find the max current a particular transistor would give according to it datasheet, witch is 1.5 amps for BD137, BD140, how much watts would the amplifier be rated for if powered from bi-polar 15V transformer, What kind of speaker could i hook up? it's pretty weird since all speakers are either 4 or 8 Ohm's.
Would be cool if you made a video on how to "design" the circuits around the transformer including the capacitors as wel filters to not pollute the grid with noise and stuff, how much capacitance you need, some guy is building amplifiers and uses 66000uF for 150 watts of power and sells these for +50.000€
I’ll get to that eventually.
@@Electronics4Guitar I'm now looking at EMI / EMC filters, but they pretty much always talk about switching power supplies or targeted at that.
Thank you sir for the nice video. I have a question regarding the frequency range of these topologies. With the same biasing condition, when I apply a different frequency signal from 10 k to 1 mega, there is a huge difference in the biasing current and delay at the output. Are there any tips for this problem or reference suggestions? Thank you
@@user-vu4nm5ns3w since this amplifier has zero negative feedback, it will exhibit relatively high distortion and low bandwidth. For guitar-oriented applications this is not a problem. To increase the bandwidth we need to add some negative feedback (at the expense of some gain).
@@Electronics4Guitar Thank you
Q2 collector should connect to -Vcc instead of ground. You said current flows from ground to RL to Q2 emitter to Q2 collector during the input negative half cycle - that is impossible if Q2 collector connects to ground directly. You have to create potential difference for current flowing. So, Q2 collector should go -Vcc.
@@user-ms8kp2xc2i capacitor C2 is charged to Vcc/2 which supplies energy to the load and allows current to flow anti-clockwise and Vo is negative with respect to ground.