a good example of a practical and common use for the common collector configuration is the linear regulator! this is a very useful and interesting application of the emitter follower topology and shouldn't be overlooked :p
Can you bias the base of a bpjt , without using a voltage divider. Putting instead, a very high resistance, single resistor? Is there a threshold of current, which below, the transistor wouldn't mind the voltage? Assuming a crude slow switching of a DC. Very soft switching. ? I mean, without the R2. I don't like the R2, because it represents for me, a power loss.
Biasing is the process of setting up the operating conditions of an active device. Many such devices require a steady current/voltage to operate correctly, so you need to set up networks of resistors and caps to guarantee this. If you look up a datasheet for an active component, it'll give you graphs indicating the quiescent point: this is the point at which the device is _operating_ but treats as no signal. For instance, you might need to supply the base of an NPN BJT with a minimum current, and you'd use a voltage divider in many circumstances to do so. That explanation is a _gross_ simplification though, and is just about biasing a single pin on a device. You might need to look at an earlier video for one that goes into proper detail.
Remember that, in order not to destroy your transistor, add a diode (+ terminal toward Vcc ) in series with a 0.001 microfarad CD capacitor in parallel with your collector . You are brilliant. Thanks. Frank
Sir please tell in TTL logic current input is emitter but in NPN transistor current flow from collector to emitter meant emitter is output please teach on that Thank's
+Jose Alfonso Hello Jose. I find Peter's videos to be useful and helpful. Have you made any videos or other material that are more useful and helpful than these ones?
Unless you know him personally or have seen his very detailed C.V., you can't tell and that is a claim without proof. He is a good communicator, and for that, the video is there to support this claim.
This guy started the basing in reverse, normally you establish first the Vce Q point and the collector current by setting the Rc and Re then you calculate the required base current and voltage with R1 and R2 , you can make tradeoff and calculations adjustments on Rc and Re depending on how much voltage gain you want and your Q point, I think that this explanation is highly confusing for the viewers.
I don't think anyone should take the piss out of mr spark fun , this guy is no dummy. In electronics there is always some clever ass who claims he knows the subject better than the "other guy". A sort of boxing match of who knows more than the other guy. I studied this subject for years and i know nothing compared to mr spark fun.
How can you know so much about electrical engineering while having to raise a family (I saw your child's photos). I am 60 and I do noyhine except study the sciences (I clean house while memorizing cards of formulas). I like your littie friend on the board. Frank Frank Reiser Video/Audio Service
I thought that was nicely presented and easy to listen to and to learn from. You're a good teacher and not all full of yourself. Greetings from Arizona.
Hello I have a question regarding input impedance that you are speaking in the video, could someone explain the me the "impedance" therm, I am new in electronics and I can not understand the therm.
Alin Dragan Impedance is similar to resistance and is calculated for AC circuits like resistance is for DC. It's how much the circuit "resists change" and is calculated in terms of Ohms.
You're a good explainer but you beat around the bush so much. For example you go: "If you think that electronics is an exact science, brother (or sister) you might need to think again". You go astray like that a lot... Why try to defocus the viewer from the subject matter? This would be so much better with less clowning and more continuity. This stuff is complex enough so why make the viewer wonder all the time "What are we talking about now?" Friendly advice.
At 20.33 you say that the output impedance of the emitter follower is approximated by the output impedance of the source divided by Beta. Well what if the source is a current source? well I would rather you have taken into account the base biasing resistors too. Still you did say approximately and you do know what you are talking about. as a very practical man. I am glad that you like the BJT for its non-linearity as this can achieve more functions, as multiplication hence modulation and demodulation. I like your informal style of teaching, good man.
Uhm i think this video has lots of confusing info, vin and vout doesnt act on the transistor voltages, thats why engineers use capacitors to isolate the input signal from the DC biasing
"we'll just say is V+ over 2, which it's not necessarily ever going to be" *flashes EPIC trollface" I just lol'd too much. Btw thank you. I don't know if it's past 3 weeks of trying to understand electronics building up, or your explanation, but I think I'm actually starting to get things.
Am I right that if in emitter-following configuration you bias the base to the point where transistor goes into saturation at the emitter you will get Vcc?
On the common base example you mentioned antenna impedance matching as a potential application. Would I be matching "Rin" to the impedance of the antenna? Furthermore, is there a quick and dirty way to determine the impedance of an antenna?
Thanks Pete! I'm working on stereo receivers and am having trouble setting the bias on one channel so I needed to learn more about what the heck is going on here in a very specific fashion. Your explanations and editing are great. (Editing can be a problem with some of these other folks videos). You're doing great, keep up the good work and THANKS!
dude, I know you know your stuff, BUT you need to work on your explanation, do each configuration at a time. to do all of them at the same time is a mess!
Dude... I truly appreciate your enthusiasm. However, as a "Noob", I NEED for you to speak more evenly, and use punctuation pauses. I am not stating this to be judgemental. Your enthusiasm would make you an awesome instructor. But, for those if us who need this, you are throwing terns and theory at us with a consistent flow. With no pause for us to digest, you may as well dump a steady flow of water in our mouths without pausing for us to swallow. Together you and I are spilling information all down my face and the front of my metaphorical shirt. PLEASE, consider these factors and re-explain with another video, which I am sure will be amazing. Please be merciful to your Noobs. :-D
Thank you! You explain this better than my professor. I find it hard to take notes and at the same time keep up with what he’s explaining. If I’m not taking notes and just pay attention I understand it easier. But then I don’t have any notes lol. So I’ve been taking notes and looking everything up here on RU-vid to understand it. I have found a few really good RU-vid channels including yours. Thanks again!
That is fine if you work with 10V, but if you work with 2.5V, you would likely consider (or be aware) that a silicon diode can have its forward voltage from 0.55V to 0.85V with the later more frequent for integrated circuit and around 0.7 for discrete component. But a little bit as for LED you would see that the "knee" is FAR from being well defined value, anyhow.
Finally, a channel that is a) Good audio quality, b) actual english, c) and real-world applicable. If you want to pass a test, go read your circuits i.e. algebra book. If you are a professional engineer that needs a refesher for a quick understanding to get a job done...boom.
Biasing is setting the voltage to the gate/base of a transistor so the transistor can behave in a certain way. E.g. for power electronics, typically setting the gate voltage of a MOSFET at 12-15V saturates the MOSFET making it ideal for switching.
Lundistani Shitteater For something like that, I would not bother using an NPN transistor. Typically the current flowing through an npn transistors depends on the base current going into it. In fact, BJT are typically good for current amplification and voltage amplification. My suggestion is to switch to a mosfet and use pwm to control the brightness. Before doing that, I would first find out the current the light bulb is consuming as it will affect the mosfet selection. Hope this helps. Good luck!
Lundistani Shitteater Are you sure it's not the voltage drop across the p-n junctions (0.6v ish)? With bulb connected directly to 6v battery; Power = 6v x 250mA = 1.5w. With transistor however - Power = 6v - 0.6v x 250mA = 1.35w
Lundistani Shitteater The hFE of a 2n2222 is usually around 250, so to get an emitter current of 250mA you'll need a base current of about 1mA. Try connecting the base directly to the 6v rail or use a low resistor
Yes. If you had 1mA base current the maximum emitter current will be 75mA. A 2mA base current will be 150mA. Max emitter current = base current x hFE within the limits of the transistor.
Video looks good so far, but it's really bugging me when you write a zero with Ø. -Stop it. If you want to discern the zero from the O then use a horisontal line inside it. The Ø is a real letter in Norway and Denmark, besides it is the international symbol for diameter.
Wow, a LOT of Americans do it that way. Pete is not Norwegian or Danish, and to expect him and a lot of other people to change their ways just because you aren't used to zeros written that way is pretty entitled.
