Transistors biasing, and amplifiers
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- เผยแพร่เมื่อ 26 มี.ค. 2018
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Transistors biasing, and amplifiers
In this video we look at how transistors are biased, a simple amplifier, and how temperature effects transistors.
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Me: Paul, 49 from USA
Education: United States Navy, University of California at San Diego B.S. E.E., University of Pittsburgh M.S. E.E.
Experience: United States Navy STS, Bayer Intnl Process Engineer
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I did your wee survey on whether we want more microcontrollers or component based circuits, like this one, but to be honest what I like about your channel is the variety! Keep 'em coming! ;-)
Thanks, I'll do my best.
Hello, thanks for the video!
Could you tell more about the clipping ?...
Thanks, good info as usual!!
Thank you, Dave ☺
While looking at the circuit diagram, on the right side of the schematic, there is a capacitor and resistor(C3 and R5). Does this not make a high pass filter?
Hiya - very interesting video. Can you post a pdf with the initial math you showed or point me to a reference please as it seemed much clearer to me than other explanations. Cheers!!!
Hi, very interesting video, I’m particularly fond on the math too, I think anyone working with transistors should understand it or they’re not going to get very far.
I’d think a great addition to the video would be to show people how to remove the clipping.
How?
The calculations went right over my head but the transistor biasing and amplification were very well explained. Definitely learned something.
It's normal the calculations went over your head as they are wrong
I think you may have overheated my transistor with the math you didn't get into ;-) Simple amplifier and a boatload of connections, thanks for the interesting video!
Thanks buddy. I never quite know how much math to get into on TH-cam. I figure you guys would rather see the demos than listen to me blather on about Kerchoff
Hello. Do you have any info on that transistor tester you used in this video? 6:49
Applicable & interesting
Easy for you to say!
Very good thx
Is the output signal out of phase or did you move it for an easier comparison? This is a common collector configuration is it?
Reason I ask is in the examples I've seen the in phase output is taken between ground and the emitter lead.
I also have drawn load line and it appears as if your base resistor is slightly too low in value and is pushing the circuit towards saturation. It isn't keeping the base current low enough to keep the amp in linear operation.
I didn't understand why the clipping occurs on the negative side, and how to effectively remove it with a circuital solution.
it happens when the biasing is not done perfectly i.e the biasing is not completely in active reqion rather its close to cuttoff or saturation which is why a small piece of signal gets clipped off.
but how did you calculate the resistances and capacitnces ive been trying to bias transistor but even after calculations and simulations i cant get it right
some good information there Paul, Thanks. I wonder if you could do a video on VCC vs. CDD vs. VSS vs.... etc.
I have been reading up on it a bit but still somewhat confused. I think perhaps a verbal explanation would be helpful. You seem to have a way of explaining things. keep up the good work.
Thanks. I'll do it.
VCC Voltage Collector Current
What about inverting output, will that cause any problems
I like how he ends the video saying “PEACE”.
I end every video by saying peace.
learnelectronics Yes i knew. i mean i think its a very good ending. Unlike other youtubers video ending.
Thank you very much. We need all the peace we can get in this life.
Thank you very much. We need all the peace we can get in this life.
learnelectronics 100% agree. You can not be enough peaceful anytime.
Believe the dim and slow-to-react LEDs on modern car dashboards when it's cold is due to the same thing...need to wait till the transistors warm up (please correct me if I'm wrong)
Very deep
Wait...the current from the base also flows through the emitter? Thought it only opened the valve.
If im not wrong RE (emitor resistor) actually acts as a thermal balancer
I understand this is not an in depth explanation of the biasing/amplification subject but it would be nice to see how you determine the actual amplifier gain (mathematically) and what can be done to prevent clipping. Is it possible to determine if the signal will be clipped just by doing some analysis of the circuit ? Finally, in order to demonstrate the circuit sensitivity to the ambient temperature, how about spraying the transistor with some coolant or perhaps heat it with some hot air, just so that we can actually see the effect on the scope. After all, an image is worth a thousand words, isn't it ?
Part 2 is coming up...
More breadboards please
First...get rid of the uneven clipping then go from there.
That "uneven" clipping is a result of the miscalculation of the bias point!
About amplification... can one use the same circuit for one thing to be amplified be used to amplify a different um thing for lack of a better term in my presents of mind... ie can i use and audio amplification to amplify a non audio signal or can I use a boost converter (amplifies power) as an audio amplifier?
If the answer is yes (or rather technically yes, but we typically use differen methods that work better for their respective applications) than I think I understand.
If the answer is absolutely not, a boost converter wouldn't make audio any louder... note; I do understand that if it would technically work, it would probably sound atrocious. But I diverge... if the answer is no, than I'm confused... how do I know what the different options are for building a circuit that's a signal repeater/booster for idk say data over supper long distances or ethernet or fiboroptic or something vs what my options of circuit types for audio amplifiers, vs what known amplification circuits are available for power amplification ie flyback (non-invrrting) buck/boost converters...
If just power amplification is different and audio and non-audio signal are the same i can kinda see that but then I want to understand exactly want's going on, on the electron level in a few of each type because I want to understand how we treat different attributes of electricity differently in order to effectively amplify that given attribute.
('Attribute' [of electricity] is the word/phrase I came up with for 'thing' ... I'm still searching my mind for a better term.)
Sorry, I don't really know how to ask this so if anyone who might want to answer needs me to clarify, don't be shy to ask, it's okay to imply that my question is horribly put... it is, i know that, it's just the best I could come up with in this moment.
A boost converter works by rapidly switching an inductor on/off. An audio or signal amplifier works by allowing a small current between base/emitter to control a larger current between collector/emmiter. Totally different circuits. The amplifier requires a separate input signal. The boost converter has no signal input. There is no where to inject a signal into the boost converter. It just takes your input voltage and multiplies it by taking advantage of the properties of an inductor.
learnelectronics okay, so what if your signal was pulses of voltage, (varying differences in potential from say near zero to idk say 10V) ... would the 'signal' be lost in the inherent oscillation of the circuit or would a 'volt pulse signal' be something that could make use of boost converter as a signal booster aka amplifier? I mean this is just theory, obviously because why would one want to transmit signals in such a way... especially since it's a solution to an already solved problem.
P.S. So technically ALL signal amplifiers can be used for audio and vice versa? It's just that some are better suited to one or the other?
Yes any amplifier can be used for signals or audio. But some that rely on pwm are no good for audio. As for your other question, that's out of my scope of knowledge, sorry.
learnelectronics no worries, it was just a wild hypothetical... is there a good reference on which are best for which application?
I ask all this because I've been researching amplifiers and have yet to see a clear distinction between amplifiers... I need an amp that outputs via trs/phillips/3.5mm headphone jack (too many names, sorry if i forgot the name you use for it) and can push 8 speakers that are wiried in the less common non-advised way (I forget if it's serial or parallel) but there's one way everyone agrees is typically the most favorable and then there's the other way... which is apparently how antique shops (the shop it's self is antique not what's sold in it...like the building is 102 years old) anyways suffice it say the least favorable way is how it's gonna stay wired... so i need a really powerfull amp (ie the impedance should do bad things to most speaker setups) and I need it on the super inexpensive... I don't want to make one, I fear it wouldn't work out too well and would thusly just cause more cost, but I feel since I'm studying electrical engineering I should be able to grasp some basics about how they work that I could leverage to make a more informed purchase.
Sorry, I use too many words; what I mean is I'm asking all this to a practical end, and to some extent, for education. Except exploring the idea of making a boost converter into a viable amplifier of some strange sort, that was just a wild hair up my... definitely not practical.
Anyways thanx for all the replies prof. learn.
It's all good. A class a-b is a classic high power audio amplifier.
Back in the day when I Was repairing HIFI equipment some manufacturers used DC DIRECT COUPLING on their Transistors.
When one transistor went bad the whole lot went bad, that's why they use coupling capacitors now..
I'm not sure why the sign/square wave was happening on your scope, can you please let us all know.
Great video thanks..
Does kirchoff's law account for current loss via transference of electrical energy to thermal energy? I know in this application it's negligible but in a more complex circuit I could see negligible plus negligible plus negligible eventually equaling significant or at least an amount worth accounting for.
No it's strictly theoretical.
Having the oscilloscope view was nice to see how the signal flowed. What scope would you recommend? (regardless of electronic experience, thinking quality over learning curve)
Anything from Siglent. They are excellent quality at reasonable prices. You can get an entry level scope for about $300 or go big for a mixed domain scope for just under 10k.
@@learnelectronics glad to know! I've got a siglent in my shopping list that's been waiting until I could research more.
It's the "Siglent Technologies SDS1202X-E 200 mhz Digital Oscilloscope 2 Channels, Grey"
Model on Amazon
C2 removes the local feedback which results in increased distortion.
What does C2 actually do?
Inorder to make amplification independent of transistor , remove the emitter capacitance , this way amplification is Rc/Re 🙂
but this amplifies half a wave. normal amplifiers amplifies full wave
IbRbUbb=- Ube= gibs me da heebeejeebees.
Useless tutorial. Do NOT use textbook.....use basic setup....not oscilloscopes...
we are here not to hear you say pppppbbbb