As many below have already said, you do a great job of explaining things. I really, really appreciate your explaining about what is happening with voltages, currents and watts at various parts of the circuit. It seems not many RU-vid videos go into talking about this. Finally some basic things of electronics are starting to make sense to me after 4 years of trying to learn what I can, thanks to your videos. Keep up the great work and thank you so much for taking the time to make these most excellent videos! Subscribed!
After vainly struggling through myriad books trying to understand the basic principles of transistor operation, it is such a pleasure to have found your video series. Many thanks for presenting this content so clearly.
You Sir, are the best electronics channel I've found. Wanting to learn more about electronics at 59 has been a bit of a struggle for me to understand. The way you explain things makes me understand all the other videos I've watched before I found your channel. Cannot wait to watch all your learning videos. Thank you!
I don’t quite understand the voltage across C and E in the voltage regulator example, because in part one it was mentioned that if the transistor is turned on then it should behave like a closed circuit. Which means the voltage across C-E should be close to zero. But yet the example used 2.7 V across C-E Which means there can be a voltage across if there is significant current flowing through, simply because there is still a small amount of resistance between C-E when the transistor was turned on. Is this a correct explanation?
No, it's not for any resistance as such. Like you said, there *could* be enough current to short the transistor. Let's start at the Zener. See, the Zener essentially keeps the base voltage at 10V. (Everything above that is going through the Zener to ground.) The emitter Voltage now easily goes up to 9.3V (through (partly) base and (mostly) collector towards emitter). Now this is critical: As soon as the voltage there tries to go above 9.3, the voltage from base to emitter will go *below* 0.7V. But that's the voltage you need to open the transistor. So when that happens, the current is too little to keep the transistor fully open. It starts to throttle it. (You *could* regard this throttling as the resistance you mentioned, but it would lead you on a wrong track, I think.) So the transistor essentially limits its own output to Zener breakdown voltage minus base-emitter voltage. And - different from what a fixed resistance at that C-E connection would do - this is, up to a melting point, independent of the collector voltage. The C-E voltage therefore will always be collector voltage minus (Zener breakdown voltage minus base-emitter voltage). With 24V, you therefore would have 24 - (10 - 0.7) = 14.7V across C and E. Good question, though. Exactly the stuff I was asking myself so often.
I studied electronics as part of an apprenticeship and nobody explained things like you do. It was just, heres the maths and work out some examples. Maybe build a circuit on workbench. This is the way electronics should be taught. Less maths and more practical examples.
