Electronics - Using an NPN Transistor as a Switch

[zameersl1]

its nice and useful for me....

[michaeljudge88]

@zameersl1 Thanks, glad I was able to help.

[8888ACE8888]

damit u deserve a subscription from me!

[michaeljudge88]

@8888ACE8888 Thank-you sir:)

[FukinExplosions]

Just like a relay

[ismaels91]

Nowhere in the word transistor does it mean 3. You kinda stated it did. Anywho

Yes it is using the transistor as a switch but you are using the same power supply. All you did was make the circuit more complex. Removing the power source from the 3rd leg on the transistor made the LED turn off same as if you didnt have the transistor in the circuit.

[seraine22]

@ismaels91

You are correct, transistor was actually a combination of transfer and resistor. However, using transistors as a switch can actually be very useful. For example, I have a photocell that can only take a few milliamps, but a motor I'm using needs 3/4. I can use this way to make a simple(when compared to other methods) light activated motor.

[milesdavidsmith]

@ismaels91 LOL ur dum

Plus this is the basis for all digital logic. I've sort of learned that it's best to remain silent and remain an enigma then to speak up and look like a smartass :)

[milesdavidsmith]

@milesdavidsmith Anywho

[jeta45]

Great Video. Very clear quality video. Can you do one on Darlington pair circuits please. Like showing how to turn on LED's through a darlington pair by touching the base.

[michaeljudge88]

@jeta45 Thanks for watching. Also I got around to doing a Darlington pair circuit, just check out my channel to see. Thanks for watching my videos:)

[jeta45]

Excellent video explaining how to wire up an NPN Bipolar Junction transistor circuit as a switch. Seriously, I've watched many videos and this is the best to follow along with. GREAT JOB!!!

[michaeljudge88]

@jeta45 Thanks a lot:)

[directcurrent10]

wht type of transistor did you use in that circuit????

[michaeljudge88]

@directcurrent10 Just a regular 2202 or whatever, off the shelf crappy one

[jeta45]

@directcurrent10 He was using a Bipolar NPN junction transistor. I was following along with my breadboard and components wiring it up just as he was and it worked just like his did.

[directcurrent10]

@jeta45 i know its an npn.. what im asking is the model of it.! to buy one.! but by the way thanks for sharing..!

[AugendesAbgrunds]

Of all the videos on youtube, this is the most useful. I've spent hours trying to make sense of it and you explained it in under 5 minutes.When spiderman dies, you'll be my new hero.

Any chance of a 555 tutorial ?

[michaeljudge88]

@AugendesAbgrunds lol thanks, I try to keep things simple. Glad I could help. I'll be sure to put up some videos on a 555 in a bit. Thanks:)

[mcm1322]

Question, whats the significance of using a transistor as a switch? Why not just use a regular switch?

[OffroadMachine115]

@mcm1322 u can use a transitor like an inverter. if u want a to ground a circuit with a positve charge it is easy

[Miangullion]

Hello this is very helpful thanks for the upload. Kindly mention the resistors values. Also can some body tell me how to increase the rate at which the this trans switch circuit will on & off more quickly?

[redpunk]

i bought a transistor. depending on what side of the package you were reading it was either going to be npn or pnp

[redpunk]

@redpunk i also didn't realize i'd been here before

[michaeljudge88]

@redpunk lol Its all good:)

[redpunk]

don't take this the wrong way, but you look like an engineer

[jake3085]

Thanks for this tut i finaly get it now this helped me lots. If i run a freqency into the transistor can i have it pulse the device its powering at that freqencie?

[michaeljudge88]

@jake3085 Yup sure can, whatever frequency you apply at the base will be replicated in the output. So if for example you were to send a pulse to the base at 1 second intervals, current will flow from the emitter and collector in the same fashion.

[Charles2337]

I wish you were my buddy in college. You would have helped explain a lot to me haha

[michaeljudge88]

@Charles2337 Thanks:)

[kwaknit1017]

@michaeljudge88 thanks men...... but I have a question, what kind of transistor are you using? and according to my research the 1st pin to the left is the Emitter, the middle is the Base and the last to the right is the collector(front of the transistor is flat)

... I am using 2222A transistor....

[oneman46613]

Good job !!!!



[TheDragothica]

I really don't understand, what the transistor is used for in this circuit. It's not actually the transistor, thats being used as a switch, it's the fact, that you break the circuit, by removing a wire to ground... you can do the same without the transistor.

[michaeljudge88]

@TheDragothica This was an overly simple example about using a transistor as a switch, the main focus is using a small base current to control a larger current, for example activating a 12 volt relay with a 3 volt battery or something. Perhaps I will post another video explaining that better. Sorry about the confusion.

[TheDragothica]

@michaeljudge88 as far as i call tell from the video, the two resistor on the board and is the same ohm size - which i think makes the confusion - cause you could do the same without the transistor. If you did an led array with 5 led's (or using a component that requires more voltage), powering them with 9vdc from the top rail on your board, and then powering the base with a 3v battery, it might be more understanding.

[bsdaemon666]

@TheDragothica It's simple, you have to apply voltage to the base of the transistor in order for current to flow between the collector and the emitter. Think of it as a similar function to a relay.

[MintEEV]

Burnt my fingers... All my transistor does is heat up really bad. HELP!

[michaeljudge88]

@MintEEV Are you using a resistor connected to the base of the transistor? You need one of those, also how much voltage/current are you running from the collector to the emitter? Common transistors have very strict (and not overly large) ratings.

[eagle282828]

bro! thx for this vid understood everything i needed to, thanks again man!

[michaeljudge88]

@eagle282828 Hey no prob, thanks for the comment:)

[oscaraigle7601]

Thank you very much for this video! It's very informative, and helped me a lot understanding how NPN transistors work, even in english which isn't my native language! :)

Thanks again!

[michaeljudge88]

@oscaraigle7601 No prob, glad I can help out:) Thanks for the comment.

[mtdeezy]

I hate classical electronics. When you say a positive voltage, that really means negative, right? So electrons flow from the collector of the transistor to the emitter, and to activate it you put electrons into the base? And by the way, how the hell do you know when to use classical, and when to use the real terms?

[michaeljudge88]

@mtdeezy Classical terms, "real" terms. It really doesn't matter. Pick something that works for you and go with it.

[mtdeezy]

@michaeljudge88 It really does matter, because if you tell me I need to hook the positive side of a transistor, or diode, or what ever up to something, but you really mean the negative side... that makes the difference between a functioning circuit and a very organized piece of junk.

[michaeljudge88]

@mtdeezy Best of luck to you sir.

[ZuffsStuff]

Hi there, I have a question. I copied the circuit just like yours, but the wire that is supposed to be used as a switch does not change the current whatsoever. Could the transistor I'm using be different? Mine says C9012-H116. It might even be PNP; I can't really tell them apart from NPN.

[michaeljudge88]

@ZuffsStuff Sorry for the late reply, it could very well be a different transistor. The only way to tell is using a multimeter or putting in it the circuit and observing results.

[ET2uscg]

Thanks man , any info  is great those are clear instructions.

[gardiner1986]

can you make a timer detonator from this type of circuit?

[echaculpas2010]

thanks mi frend hllo from mexico see later

[kcinkcinkcinnick]

zo npn is CBE  with the flat side to you ? ...

because in other vids they say that with an npn resistor its EBC ... --'

[crazylazystacy]

@kcinkcinkcinnick i notice the same thing and i am 100% sure that if the flat side is facing you then its EBC and the reason that this worked its because the Collector on a transistor usually goes to a positive feed and the emitter to a negative. so i think he just got lucky:) great video tho!!

[michaeljudge88]

@crazylazystacy Thanks for the comment, ya sometimes it can be difficult to know what transistor your working with. Recently mine got mixed up so now I have PNP and NPN's in the same box.. Oh noes!

[reloopx]

great tutorial!

[lowsideswitch]

great job explaining it but you had a working circuit before you put the transistor in, did you gain anything by using a transistor over a relay? and is there any reason you switch on the low side?

[lukel99]

@lowsideswitch You gain the ability to switch high currents with a low current source. An example would be if you wanted to turn a motor on or off with a microcontroller. If the microcontroller can only supply (for instance) 40mA per pin, and the motor takes 200mA, the transistor allows you to switch the higher load. Transistors switch faster than relays and use less power. Relays can handle more power though, so many times relay coils are switched by transistors.

[luxoflynn]

Excellent explanation. Thank you!

[dhonfrey]

what is d value model of the transistor that u used?

[michaeljudge88]

@dhonfrey It was an 2n3904. Its a pretty common transistor type. Thanks for watching my video, sorry I took a long time to reply.

[funbidoux]

Exactly what I was looking for! Thanks!

[scriewy]

but how do people make the flashy circuits ?

i saw dozens of vids, and no 1 explains WTF is going on, and they use 2 transistors what makes it even more confusing. i did understand what you explained now though, very clear step by step.

how i arrange the parts so the turn on/off signal is not done by me connecting/disconnecting the base to battery positive, but electronically ?]

thanks

[michaeljudge88]

@scriewy Hey thanks for the comment, to make the blinker circuit, most people use a combination of capacitors and resistors. the caps are charged and drained through resistors when enough electrical energy is achieved to activate the base of a transistor. I will see if I can toss up a vid explaining all of this clearly, then I'll let ya know :)

[tHaH4x0r]

@scriewy

if you cant wait for the vid, look up on wikipedia or google "astable multivibrator" thats the circuits name ;)

[Matthington10]

THIS IS THE FIRST TIME IVE KNOWN HOW TO USE A TRANSISTOR AND HOW IT WORKS! thanks :)

[MrMimsicle]

This helped me understand a lot better how NPN transistors work. Thanks.

[michaeljudge88]

@MrMimsicle No prob, glad I could help :)