NPN 2N2222 transistor component as switch circuit with schematic tutorial. 2N2222A 

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Anupama Mehra glad to hear!

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Sweet!

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Welcome back, hope you were having fun, all is good, hope all is well with you.

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Thanks for watching! Yeah. I almost always use a couple longer jumpers to connect the 2 rails together when I use a battery.

I don't really have a beginner book that I think is best, I've enjoyed electronics for dummies, practical electronics for inventers and Complete Electronics Self-Teaching Guide with Projects to name a few. I think most people would be best off learning the basics from free websites and RU-vid videos while also consulting the Art of Electronics book, which is packed full of good info at for all levels, but may be too confusing by itself if you haven't done other circuitry study and/or experimenting.

Glad to help, thank you for watching!

Just completed this project today but went a bit astray following the schemetics, in defence I'm fairly new to the hobby. However, followed you in the clip and all went well. I'll be stripping and re assembling this one a few more times now until it all falls into place. Thanks again for the project and the supporting information

Don't worry, long as you are learning and having fun, every project is a success!

Apparently so lol, thanks for watching!

Took the words right out of my mouth.

I heard his friend lives in a van down by the river😅

Glad to hear! Thanks for watching!

By using Ohms Law

@@nxbil2397 Then the question becomes how did he determine how much current to supply the base

You expecting him to answer that? He will answer you if you just tell him how great he is. Just look at all the comments he answers. It is a dead give away. :-)

For a 2N2222, you look at the datasheet and see that the manufacturer specifies the base current as 1/10 of the collector current when operating as a switch (called in saturation). So whatever collector current you need, you design for the base current to be 1/10 of that. For example, if you plan to drive an LED, which needs about 2V to light up, in series with a 330R resistor from a 9V supply, you will get Ic = (9V - 2V) / 330R which is around 20mA. So you design for a base current of 2mA. The transistor base-emitter junction needs about 0.7V when conducting fully, so you use a resistor of (9V - 0.7V) / 2mA which is about 4K. A 4.7K resistor would be fine, as it's not critical.

Thanks for watching them! PNP emitter go towards the positive side of the supply (Vcc) and collector goes to the negative side of the supply (ground). You need enough resistance when the base is to ground to keep a low amount of current flowing from emitter to base. You also have to make sure there is enough resistance to limit current from emitter to collector. Here's a PNP bipolar junction transistor (BJT) demonstration circuit video that should help ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NNgb97PiJw4.html

+Alexander Vinson 1 amp at 12 volts would be 12 watts of power. So you would need a transistor that can handle 12 watts, much more than the one in this video, but otherwise it sounds like your plan works just fine. I added a link to my facebook page facebook.com/electronzap/?ref=aymt_homepage_panel to some power transistors that are rated for 6A and 100V. I haven't used transistors that powerful yet so I have to recommend you read whatever datasheets you can find on them for wiring and heat dissipation. I just noticed that the base of these transistors is rated for 5V which I am guessing is what the function generator outputs.

you can use a power transistor

Sadly, I am pretty sure that I don't have either of those. I plan to someday make videos on specific transistors so I will keep them in mind :) Will probably be a while before I can though unfortunately.

The BC557 is a PNP transistor. The BC series are generally European and have counterparts in the 2n series. The 2N3906 will substitute relatively well for the BC557. Most use cases call for NPN transistors and very rarely does a PNP need to be used.

They are confusing at first, but once you figure them out, they are a lot of fun :)

Weird thing about electronics is that something that totally baffles you, all of a suddenly makes complete sense one day lol. Putting the load on the emitter side of a bipolar junction transistor is called an emitter follower circuit. Whatever voltage you apply to the base, will be the voltage at the emitter but with a diode drop. So, 0.6V less at the emitter than the base for the NPN BJT. The base doesn't provide the current for the load, the collector does. So that's a useful circuit when you have a signal voltage that you want across a load (minus 0.6V) but the signal voltage can't provide the current needed to power the load.

@@Electronzap This is probably my 5th go at it but managed to make some good progress this time. These short intro and explanations are really useful. I watch 'em then make them then have a play around to see if/where I can add them to others. Its good channel you have here matey its very much appreciated

@@utkf16 Glad the videos help!

It is confusing, ultimately you have to read data sheets to know for sure. I am slowly working my way to making a detailed video on this topic, but remember that the 2n2222 is a NPN - Bipolar Junction Transistor. I also use the 2n3904 a lot, which is also a NPN BJT. The 2n3906 is a PNP BJT so it's chemistry is the opposite so the polarities of voltage and current are opposite as far as the pins go, but other than that, has the same power handling limitations as 2n3904. Then there are whole other families of transistors, so no matter what, you have to look up what it is on its datasheet, based on it's part number. The 2n3904 and 2n3906 can not handle near as much power as the 2n2222. I think the 2n3904 can handle 150mA of current from collector to emitter verses the 2n2222's about 700mA collector to emitter current. I am on my phone so can't look up the exact numbers right now. The 2n3904 can switch faster though, I never tried to memorize how much faster as I only do extremely slow switching. For my circuits, so far I generally use no more than about 20mA of collector to emitter current and as far as I know, any BJT you find can easily handle that. Also, not all transistors have the same pin lay out, the base-collector-emitter may be switched around even if it has almost the exact same properties as the 2n2222 but is different part number.

electronzapdotcom thank you!!!

No problem! Thanks for watching!

Vinicius Alegreti Meza You should be able to use a 2N3904, which is a very common transistor. It's very similar to a 2N2222.

I have had no issues swapping random transistors in and out of my test circuits. If you get the polarity wrong they just don't pass current ... just make sure you limit the current you send to the base. Too much current into the base will destroy them.

The 2N2222 component also comes in a metal can, which has the opposite pin layout from the plastic (TO-92) package. There is also at least one variation in the plastic TO-92 package that has the opposite pin layout.

ZTX751 is a PNP BJT according to the google search I just did. So you can use it in a PNP BJT switch circuit that other transistors of equal or lower power rating are used in. Always pay close attention to the pin layout when you substitute another transistor of the same chemistry. It is often different.

Thanks!

@Ven Go im pretty sure it makes no difference though.

There's not a ton of difference between switch circuits when it comes to using different types of transistors other than different pin names, input signals needed, and conduction limitations. Just need to look up the pin layout and whether the load is on the high side (more positive) or low side (more negative/ground) of the power supply in relationship to the particular transistor wired as a switch. Also need to make sure the transistor can handle the voltage, current and power needs of the entire circuit. Sometimes you will be able to pull a particular BJT out of a spot and replace it with a specific MOSFET which will work just fine, but you have to make sure they are either cutoff or saturated with the same voltage and that current is still safely limited. Mostly though, there's way too much transistor variety out there to try to make a universal switch circuit where you could just throw any random BJT or MOSFET transistor into it and it would work. It's best to just look at other people's switch circuits that use the same type of transistor that you want to use and design your circuit based on that. If you want to design a transistor circuit from scratch, then you need to study the datasheet of that transistor and stay within all it's limitations. Hope that answers your question adequately!

@@Electronzap thank you for your help

The pin layout depends on the part number. All of the TO92 package bipolar junction transistors I have come across, that start with 2N.... are emitter on the left, base middle and collector on the right when looking at the flat side. Other part numbers will likely have a different pin layout.

@@ElectronzapThank You for Your kind reply Professor . I believe it is the BC547 NPN that is reversed C B E rather then EBC , and i always thought all NPN were pinned out the same,

@@Electronzap I guess I am newbie when it comes to some components, my favorite always was the 222n, i recently discovered the BC547, and, BC558 and had no idea they were laid out differently (BC547) CBE

Takes a while to get used to different pin layouts. There's nice component testers out there that you just put a component into pin holders, and it automatically tests it and tells you what it is and the pin layout. I might make another video of mine soon.

@@Electronzap Yes I did get the Transistor tester as well believe placing the flat side facing me pin 1 2 and 3 then test it shows me the HFE and pin layout. Of course only by Your consent I watch all video You have in Electronics :) and some from other people but Yours seem to stick with basics more which i appreciate even moire Thank You

Lol, all topics are allowed as long as they aren't attacks on people. N-P-N is the chemical make up of the transistor. But the connections that need to be made are definitely confusing for a while, so it'd definitely be nice to have a system set up that is helpful to people learning about a component.

electronzapdotcom I'm glad that you second my motion this could be a historic thread here. semi conductors are made from silicone on a side note npn and pnp are suppose to denote positive and negative but that formula doesn't work for the last letters of the transistors code, so I was thinking we change how we write tell code to match the polarity of the transistors pin like this npn = npp negative positive positive, and pnp = pnn positive negative negative. Cheers

In Saturation Beta Counts? When In Saturation Collector current Flow is Max and no more depedent on base Current..as per my Knowledge

@@muhammadawais7288 In saturation, we would expect collector current to be limited by the value of the load and the supply voltage. However, the saturation voltage of the BJT, Vce(sat) depends on the base current. You have to overdrive the base to ensure that Vce(sat) falls low enough to keep the dissipation in the switching transistor within acceptable limits. Take a look at the manufacturer's specs of any non-Darlington BJT. You will see that almost all specify a base current one tenth of the collector current when giving the maximum value for Vce(sat). The few exceptions like the BC547 family are specified with Ic twenty times Ib. Take the popular 2N2222A for example. The datasheet quotes a maximum saturation voltage of 0.3V with Ic = 150mA and Ib = 15mA. That's an assumed β of 10. It also quotes a maximum Vce(sat) of 1V at Ic = 500mA and Ib = 50mA. Again a β of 10. In the first case, that's a power dissipation of 0.3V x 150mA = 45mW. In the second case, you get 1V x 500mA = 500mW, which is at the limit for dissipation of a metal TO-18 case without a heatsink. If we use less base current, the saturation voltage could be higher: the manufacturer does not guarantee it and you could end up with more than the specified Vce(sat) and exceed the power ratings.

That's an emitter follower. You lose 0.6V, but you can turn things on and off that way. The load will get whatever voltage you give the base minus 0.6V.

Probably rushed too fast when I drew the schematic. Order doesn't matter electrically, but typically the resistor is placed on the more positive side of LEDs in both schematics and actual circuits.

@@Electronzap Thank you for the clarification.

Thanks for watching!

You can! Thanks for watching!

I used that much resistance to show how a really small amount of current flowing from base to emitter allows a lot more current to flow from collector to emitter. You can definitely use a 1K resistor or any other value as long as you don't exceed the power rating of the resistors or the current ratings of the transistor and LED.

electronzapdotcom the power you use is 9v right? I use 3v and i have changed the 10k ohm on resistance to the base? Also work right? Thank you for so muck explaination

That's a good point, thanks for the comment!

Search for "How to make a Tesla coil" :) Lots of videos out there. I won't be making one for a long time.

lol, 2N2222 are all over online lol. I like amazon.com. Ebay will have a lower price but a lot slower. If you need one really fast, you need to find a store that sells electronic components, which isn't that easy where I live in Minnesota. Hopefully they have the 2N2222 or a good alternative NPN BJT.

electronzapdotcom i live in morocco, and i have projet school: i want to make tesla coil.... So i need a transistor 2n2222 Please can you tell me The device I will find in it...... Please because i don't have a lot of time 😭😭😭

Please ! I need ...answer quickly 😭

No clue about Morocco, sorry. Hopefully they have good Amazon there and one day/2 hour delivery or stores.

electronzapdotcom and what about The device I will find in it?!

Thanks! The value doesn't matter as long as you stay within power and current limits and doesn't get so large that the transistor barely turns on. That was the highest value resistor I had at the time so I wanted to show that even a really small amount of current can be used to turn an LED on using a 2N2222 transistor. Usually I see a 10KΩ resistor because that should guarantee saturation.

No clue, I never built a circuit like that so I just have an idea of what each part of the circuit is doing. Looks like a lot of oscillations going on so I'd suspect an oscilloscope would be needed to trouble shoot it. I often have to slightly or greatly modify circuits that are presented in schematic form so all your ideas sound like possibilities. If you share it with people that do a lot of audio electronics, they may spot a problem with the design right away.

OK, thanks! IF you're interesting in some info: there is a Schmitt-trigger that is used to get two oscillators. Instead of simply powering to Pin 14 it works as a "starving oscillator" circuit. As I guess the every second inverter is used as a buffer (so signals can be mixed). Somehow it has "interference" of the 2nd oscillator (that is bypassed by a switch which is abcent on this schematic, it's before R1). So even when it's OFF, it slightly changes 1st oscillator's frequency and even give some lite modulations. I like this synth for it's relative simlicity. web.archive.org/web/20060402010333/www.geocities.com/tpe123/folkurban/fuzz/simplevcf.gif - it's a part of this synth. "Fake low pass response" filter. A very nice thing that allows to get a "parody" on a real LP res. filter with few cheap details. I like it for the sound. It's a bit unpredictable and a kind of "rough". Only one big con for this synth: you need a sequencer (simpliest DIY can be OK) or a MIDI to CV device. It's not a con. actually, it's how it works.

Unfortunately, English is my only fluent language lol. I know some Spanish and a little Russian. I used to watch learn Russian videos on RU-vid by RuskyEd and he comments on my videos in Russian sometimes. I like different languages though, and thought about learning how to explain electronics in different languages.

To protect an LED (about 20mA or less) that has a 1.5V drop, I'd use at least 100Ω (120 is better if you have one) for 3.7V and around 220Ω or more for 5V. Any higher value can be used, but LED won't be as bright.

Is the 470k resistor constant?

You can use almost any resistance at the base of the transistor (as long as it protects from high current and doesn't overheat), not much current is needed there so it is often better to go higher. If the resistance is high enough value to protect an LED, it will protect most anything. Base resistance is a much more complicated topic than simple component protection and depends greatly on the rest of the circuit and you need to study many circuits and the base resistance they use to better understand what values are best in what situation.

electronzapdotcom Thank you for the information :)

;)

Great content man.

Sorry!