Best Explanation of How the Transistor Works. Part 1

[edwin4759]

very interesting buddy

[SteelWheelsDown]

This is a pretty good demo, showing what a MOSFET does, and the polarities needed. It also shows the "memory effect" (capacitance) of the gate - you apply the gate voltage momentarily, but the source-drain current remains constantly on or off, and the fan keeps going even after you remove your finger. I could figure out the circuit, but it would be helpful if you included a schematic in the video somewhere. Good job!

[DancingSpiderman]

a bipolar xtor is a current-controlled current source.

your field-effect xtor is a voltage-controlled current source.

Fun With Electronics, by DancingSpiderman

[tangnatalaga]

@DancingSpiderman Very good. Thnx again.

[tangnatalaga]

@DancingSpiderman by the way I am trying to find your video "fun with electronics" can you post me the link I could not find it.

[DancingSpiderman]

@tangnatalaga haha sorry to mislead you, my friend. I do not have a vid on the subject. I am an electrical engineer,& so I remember my EE courses from college, explaining the bipolar transistor as a current-controlled current source, and the field-effect transistor as a voltage-controlled current source -- amplifiers in more practical words. But I enjoy your explanation, because they are as you say.

The line "Fun With Electronics, by DSM" just means I sometimes enjoy discussing the subject.

[tangnatalaga]

@DancingSpiderman Thanx man. Wow electrical engineer more power to you. I am scared of large. hahaha. BTW i was trying to post PWM for motor control the other day the internet was so darn slow. See you later.

[tangnatalaga]

@DancingSpiderman The FET on the video does not really care that the current is much smaller in fact million of times smaller. It responded to the voltage which is still the same voltage as the supply voltage but with such a small current. This is one reason why it can be damaged by static electricity which has virtually almost no current but has high voltage which is so much higher than a FET maximum allowable voltage.

[DancingSpiderman]

@tangnatalaga Correct. The current at the Gate of your N-ch FET is essentially Zero when current flows from the Drain to Source pins. The N-ch FET is activated by an electric field caused by a buildup of positive charge at the Gate , in this case, due to you bringing your finger very close to the Gate of the FET -- the "field effect" of your N-ch FET. The electric field effect caused positive charge buildup , beyond the On-Through threshold of the FET; current flows from Drain to Source.

[tangnatalaga]

@DancingSpiderman Very Good wow this is a learning experience to me. Anyways I am not so good at coils transformer etc. I remember a while back troubleshooting a portable generator after a hurricane. I could not get it to work. There seem to be a smaller winding that controls it to make it work. The main winding was not short or open,but somehow I did not know what to do with a smaller winding that seem to control it. An electrician whould probably know more on inductance than me.

[YourDadisHAWT]

A transistor is a semiconductor device used to amplify and switch electronic signals.

[tangnatalaga]

@YourDadisHAWT That is where people gets confused. You understand the concept I assume. To amplify means to magnify right? You can't magnify energy and novice get a notion that is what is happening. This video is for novice intended to get their mind in the right track. later on they will understand the more elaborate characteristic of the transistor which I am still working on describing in the 2nd version of this video. Thanx for the comment.

[tangnatalaga]

@YourDadisHAWT You are right with the explanation except it is often misunderstood. Since energy can not be created (or destroyed), it is not really possible to "amplify" any given electrical quantity. People gets confused because they think the actual electrical energy is getting bigger. It merely control the a bigger current that result in signal amplification. Signal is more of a mathematical expression in electronics.