Added: 3 years ago
From: sciencoking
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  • YAY, with a few lyrics and a search bar I have found this great song!♠♣♠

    •Kraftwerk The Model•

    ☻Thanks again for the video and the song!■

  • whats that song? it seems to be stuck in my brain. I also noticed that a STS 9014 NPN tansistor does this with out the need for 2 of them. (but im sure the added gain helps make an LED much brighter depending on the supply voltage im using 5V regulated)

    But anyway I want that song!!!! -=] great video/musical addition☻

  • very nice explanation !

  • I still don't understand how transitor's themselves amplify things. Correct me if I'm wrong but all they do is let current pass when a small voltage is applied to the base am I right?

  • Well, to be honest, I don't exactly know how all the (probably quantum-mechanical) effects in the transistor work, but the visible effect is that by applying a positive potential to the base, you change the conductivity of the silicon crystal between the collector and the emitter, or vary the resistance between them, which means that a perfect transistor starts to conduct a rather large current once the potential is applied to the base and a B-E-current is not even necessary

  • @Nadrealis If you mean that the input signal (ac or dc) is small then the amplified output is grater, then where does the extra voltage come from? If this is your question, the answer is simple: it comes from the dc voltage Vcc or Vgg we supply to the BJT or FET transistor.

  • @spiritualitydesire Thank you for the clarification. This was 7 months ago and since then I have taken transistor & semi-conductor courses for my electronic engineering program at my Univ. Thank you for the response.

    Cheers.

  • @Nadrealis Hi Nadrealis. I had the same question. It doesn't make any sense when someone says that a transistor amplifies anything, because the transistor itself, does not produce power to amplify a signal. What it does do, is take a weak signal, and that weak signal controls the flow of a larger signal.

    The best analogy for this is a lever.  Picture a lever with one end very short, and one end very long. When you move the short end just a little bit, it causes the long end to move a lot.

  • very cool!! now i can use my jedi force to turn on a lamp XD

    cant wait to try it out

  • What was the Transistor's Part number ? Im going to take a double look at the diagram. Adding another pair or single could make this very sensitive. It gave me some very good ideas when I seen this video. Rather Helpful ones if that.. Thanks 4 the video..

  • Very cool! Will inspire me to put together a touch sensor...

  • Der schaltplan ist ein Blödsinn...bei mir leuchtet die LeD schon ohne zu berühren..obwhl es ein NPN Transistor ist..!!!!

  • bei mir funktionierts auf jeden fall. Benutzt du ne batterie oder ein netzteil?

    Mit netzstrom muss man die Basis von T1 noch an masse anschließen (hochohmig), weil das netzteil spannungsspitzen erzeugt, die der darlington nicht mag (milli- bis mikrovolt, aber das ding ist ja sau emfindlich...)

  • ohne netzspannung....

    Wie waren Transistoren? HAts du evtl. noch die Werte?

  • ich würd mal folgendes versuchen:

    find raus wo bei deinen transistoren B,C und E liegen, indem du ne schaltung baust, die nur einen transistor braucht.Dann kannst du es entsprechend mit dem darlington versuchen :-)

    wenn du das schon weißt und die schaltung stimmt, versuch das mit dem Erden trotzdem mal ;-)

  • What song is that?

  • good video ...but wat was funny?

  • I tried it with (2) npn 2n2222 transistors and it didn't work. :(

  • well, i found put that there are many kinds of transistors that are built differently. It is possible that your type has b, c and e at different positions.

    If that´s not the problem, they could be broken. Try a simple amplifier circuit :-)

  • que hueva

  • change the angle of your camera. its giving me vertigo =(

  • I´m sorry. With my CRAPPY tripod it was very difficult to find an angle that allowed me to work while the camera was near the breadboard.

  • Nice circuit and amazing song!

  • Thanks! It´s "The model" by KRAFTWERK :D

  • oo i love that song!!!!!!!

  • @ 1:56, you put resistor to protect it from burning in case if wires conected together :P Really, it is smart to protect a transistors with 100k resistor conected to base 1

  • this is a good idea... but i thought it would be okay for the demonstration of the principle... :-)

  • ammm an stupid question : is the LED powerd by your finger or by the 9v battery

  • the transistors are amplifiers. In fact, this darlington pair works like a switch. So imagine the circuit i built here is a switch. If you touch the wire, the switch closes and the battery power gets to the led. so the led is in fact powered by the battery. The tiny current in my body just closes the switch :-)

  • Brilliant! Very good for education! :)

  • thanks :D

  • Are you sure this works with any npn? When I tried it the led didn't work even when connecting the + to the resistor

  • maybe your transistors are built different, like thorsupremecommander said below.... but it should work with every kind of transistors.

  • My fault,I was using a 470k as opposed to a .470k and I wasn't touching both the base and ground. I changed it a bit and now I have an open circuit between the + and a 10K which protects a second LED connected to the base of the first transistor. When I touch my finger over the break the LED I added is off and the original LED lights bright which shows that a very small current is enabling a larger one. When I close the break the second LED is dim which indicates the difference in current.

  • not all transistors have base in the middle. I've got some types which have base on the left :P

  • i already saw that... but it´s already in the description as a possible failure source

  • Oh yes a funny test^^

    But could you publish the wiring diagramm please?

    So it's easier for the viewer to understand the wiring and to build it ;-)

  • ok :)

    it will be on flickr in a few hours

  • the pictures are up. check the description :D

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