NPN BJT strange behavior? Answered

My linear power supply design has been using a PNP MJE2955 pass transistor wired to a 2N4401 as a complementary darlington configuration, but this was not an inherently stable design, and would oscillate when adding output smoothing capacitors, particularly MLCC types (with very low ESR). So I decided to try the far more common darlington arrangement, although I am not fond of the higher voltage drop. However the output was oscillating at approximately 3KHz with 1uF output capacitance, with NO input to darlington. I removed the 2N4401 so all I had left was just a 2N3055 transistor with the emitter connected to the output and the collector connected to a 20V supply. The output was ringing like crazy. The oscillation frequency could be changed by adding/removing output capacitance. Why is this happening? How should I go about stopping this oscillation? I originally had a 4.7k resistive load on the output but it did not significantly affect the output oscillation.

Asked by -max- 1 year ago


could i make a transistor by stacking 3 silicon wafers, N type P type N type?, and soldering wires to them? Answered

Was reading about homemade transistors, but it is really complex, so would this work?

Asked by pwnag3 6 years ago


npn transistor and impedance question? Answered

Hello , i have question about transistor .The picture below is a simple npn transistor booster .Can you give me the formula of gain and output impedance of this schematic please. Thanks! sorry for my bad English!

Asked by login721 6 years ago


Where can I find NPN (2N3904)Transistors in scrap/unused electronics, in what devices can they be found in?

I would like to know where I can find an NPN (2N3904)Transistor inside of something I may already have. 

Asked by ArtTech86 3 years ago


What practical applications do PNP and NPN transistors have? Answered

I read about NPN and PNP transistors and I was wondering what type of applications are right for each type of transistors. I understand that depending on the type of transistor the emitter should be connected to either an anode or cathode.

Asked by blkhawk 7 years ago


Transistor battery question

Hi, I want to know if I can hook up an 18v 3ah battery to a npn transistor with a max of 1a. Will the transistor only let through 1a or will it get burnt out? Thanks.

Asked by RyanF191 4 months ago


Resistors for a NPN transistor? Answered

In the circuit diagram(which I've uploaded),I intent to use a NPN transistor(BC 547) as a relay.The 9 VDC is stepped down to 5 VDC by a LM7805 and should be the trigger to the transistor,completing a circuit which needs the 9 VDC.The Collector is given the common negative of both the voltages and the trigger gets the positive 5VDC.I need a bit help to calculate R1 and R2.I had used two random resistors previously but the Load got powered by the 9 VDC even before the trigger was applied to the transistor.I figured out that the problem might be related to the resistors used. (I haven't included the caps used at the terminals of the regulator in the schematic)

Asked by Adarsh_tronix 5 years ago


what is a correct resistor to use on a 2n3094 transistor? Answered

Im connecting it to a Positive 9volt signal for a distortion

Asked by fatfoohy 8 years ago


Transistor question

Hey guys I have a question on transistors. When using for PWM setups, is the difference between each NPN (or PNP) transistor model by its specs? Such as gate voltage, max current, etc. I am making a LED touch setup made by qs, but I want to make it so that the Arduino activates a transistor to turn on a string of lights that the arduino could not power on its own. Here is the setup of the LED string. I want to replace the TIP31 in the wiring diagram with a NPN transistor (like this one). By replacing it, which pins go to which wire and do it have to add anything else to the setup? Will the new setup also work with PWM signals? Thanks! KT Gadget

Posted by KT Gadget 8 years ago


Where can I get a MPF Transistor?

Hey guys, I wish my local store had more stuff but it is kind of bad... Does anyone know where I can find or get a MPF, I bought a NPN transistor instead do you guys think it will work? I am making a sound amplifier, are there and equivalents if I don't find the MPF? Thanks, Tobias

Posted by TobaTobias 6 years ago


NPN trasistor tutorial help

I was going to try to make a transistor tester for npn's and I wanted to know a little more about them. Please give me information about this. Whoever helps me on this I give a big thanks to. Also list some projects you made with it. I'm always looking for good ideas. If you have any comment on my question or leave a comment on one of my instructables. Thanks!!!! project_builder

Asked by project_builder 6 years ago


2x bipolar transistor? Answered

If I took 2 similar NPN transistors and connected both the bases together, both the collecters, and both the emitters, then put it into a circuit, what would the 2 transistors do? Would the maximum power dissipation be increased or something? 

Asked by .Unknown. 8 years ago


variable frequency drive construction?

Hello i am working on a go kart but instead it will be powered by a 1/3 horsepower split phase AC motor. it operates off 768 watts and i am curious in using a Microcontroller and a high power H bridge to control it. can anyone help me or give me an idea on how to step up 12v dc into 120v dc and then using the H bridge to generate the frequency and also where to find some NPN transistors that can handle it and how to possibly reverse the direction of the motor?

Asked by luig 6 years ago


Need help with JFET preamp and chossing transistor ? Answered

Hello .I'm having some some problems with my current project .Can you guys help me please ! This is the schematic of MXR headphone amp for guitar .I don't have 2n4401 and 2n4403 , so i replace them with 2n3904 and 2n3906.The result is output is too low .2n4401 and 2n4403 (collector current = 600mA) ,2n3904 and 2n3906 (collector current = 200mA).If i replace the transistor with higher Ic i will have louder output ??? http://i247.photobucket.com/albums/gg132/chipmapple/mxrheadphoneampschematic.gif Thanks for advance! Sorry for my bad English!

Asked by login721 5 years ago


Why to use npn transistor?

Asked by visuu1 5 months ago


Logic Gate Help Needed Answered

I am building a Binary to Decimal converter and i need help making a flawless AND gate from bipolar-junction transistors. If someone could Send me a link or email me some schematics, I would greatly appreciate it. If you do email the schematics please make sure they are compatible with Eagle. I don't want to use a converter chip because it takes away the fun of the project for me. I have tried all of the common types of AND gate configurations using NPN's (C-fwd B-in E-collect, C-in B-fwd E-Base, Etc.).

Asked by toast5678 6 years ago


Triggering a device remotely through bluetooth? Answered

Ok, so i was hoping to set off an electric match using two phones and bluetooth. i hooked an NPN transister up so that when low voltage is applied, it triggers the high voltage output which goes to the electric match. sorry if im paraphrasing here, i hope someone out there understands what im meaning to say. anyways, what i want to do is have an app that works through bluetooth to provide the low voltage i need through the usb which hooks into the npn transister. in other words, a phones usb triggers low voltage place on transister which then gives the higher voltage output. and it does so by using bluetooth to keep it remote. so again, bluetooth triggers usb, usb triggers low voltage place, then that place lets the high voltage go through. let me know if i need to clear up anything and im very sorry about the grammar but ive been racking my brain over this and its 4 am where im at, and i got no sleep. therefor-- too tired to correct spelling errors. any help is appreciated, thank you!

Asked by XBLmonster 5 years ago





How do i know if a transistor is npn or pnp????

How do i know if a transistor is npn or pnp???? plz HELP

Asked by Dannne11 7 years ago


Will tip31c work for music leds? Answered

I am interested in this: www.instructables.com/id/Music-LED-Light-Box/ Will tip31c work rather than tip31 www.datasheetcatalog.com/datasheets_pdf/T/I/P/3/TIP31C.shtml I'm hypothesize that it will just affect sensitivity. (more or less?)

Asked by Dmxspider 8 years ago


How do i know if a transistor is of PNP or NPN type?

I want to know how to recognize the type of transistor.

Asked by bishal 9 years ago


can any NPN transistor be used to make joule thief.....and 1kohm resistor is only necessry to make it???????????

Iam making joule thief....................can i use any Npn transistor to make it and only 1kohm resistor be use???........is it work on different value of resistor.............?????????

Asked by rachit59 8 years ago


Can I use any npn transistor on this instuctables? Answered

Https://www.instructables.com/id/Blinking-LEDs-to-Music/

Asked by theVader75 7 years ago



Transistor Swithching Voltage? Answered

Looking at this data sheet: http://www.datasheetcatalog.org/datasheet/stmicroelectronics/4136.pdf How much voltage has to be applied across the base and emitter to switch on a "TIP 3055" transistor? The V-be row is the only thing that looks like it is telling about that, but I don't think that's what I'm looking for (mabey it is?).

Asked by Jaycub 7 years ago


How Do I Make LED's Fade with an already build flashing circuit? Answered

Hello everyone! In my spare time I've built a simple circuit which makes an LED flash. The flashing is controllable through a Potentiometer. I have attached a circuit diagram (made really fast, so i know it's bad) and the picture of the breadboard. Now, my question is: How can I make the LED fade on and off instead of flashing? I've tried to hook up a transistor but i've not succeeded. If everyone could help, I'd appreciate it. Here is the stuff I think could be useful that I have avilewable: Some BC 144 Transistors (I suppose they're PNP) Some PN 2222a Transistors 220uF Cap, 100uF Cap and a 10uF Capacitor. A lot of resistors. I do have more components but I don't think they could be used for this project. And excuse me for any mistakes, English is not my Language, Thank you!

Asked by Reogen 10 months ago


SMT variant of 2N3904 NPN transistor? Answered

Im looking for a SMT equivalent of a 2n3904 transistor. I found one on digikey that might be similar, the MMBT3904. Is this correct? Many thanks- Astroboy907

Asked by astroboy907 7 years ago



I have 14 NPN type switching transistor, what can i do with them?

I need some simple project(s) to use them up.

Asked by XOIIO 9 years ago


Transitor? Answered

Tôi vẫn không hiểu lắm về transtor PNP và NPN ? Nó được kết nối như thế nào và chúng hoạt động ra sao ? Làm sao để biết đâu là NPN và đâu là PNP .

Asked by Ledinhcuong 10 months ago



NPN to PNP control? Answered

So as I get into this project the circuit keeps building and now I once again have another problem that I can't figure out. As the title hopefully suggests I am using a NPN PN2222A trans. to control a PNP 2N3906 The idea was to use the 5v from a Ardinuo UNO to control a 12v. Currently I am testing with a 9v I had on hand. I thought it would pretty straight forward but every time I supply power to the NPN it creates the short needed to turn on the LED, but once I cut the power the LED stays on until I create another short (using a probe) uphill of the NPN. The only thing I can think of is that the LED doesn't the resistance needed for the power to re-saturated the PNP. Any thoughts? I will admit  haven't done any of the math needed yet for the resistors. Also can someone send me a link to the programs you use for drawing the layouts so I can move past MSpaint?

Asked by Jayccob 2 years ago


help with using a transistor npn as a switch

I am some what of a noob in electronics. I wanted to know if i am able to you a transistor for a camera switch. I have TIP31 npn transistor. what i am trying to do is using arduino to take pictures every 10 seconds or so. I know this could be done with relays but i just wanted to learn how to use transistors and how they work. any help would be great. or links on what i am trying to achive here. big thanks to every one

Posted by DELETED_kclv1988 10 years ago


Can a 2N3055 transistor be operated at voltages under 60v ? Answered

Can the minimum collector emiter sustaining voltage of a transistor be more than the power supply voltage or is that somthing else? For example can I run a transistor with a minimum collector emmiter sustaining voltage of 100 with a 12 volt power supply ? Thanks

Asked by build a BOOM 8 years ago





AM transmitter design ??

Is it better to use a diode for DSB SC modulation for good range ? or it's better to use npn transistor ?

Posted by walidj 7 years ago


Choosing a transistor (NPN)? Answered

Hey Guys, Recently I was ordering electrical components online and when I reached transistors I couldn't choose any. I was wondering that can I order any transistor or will it ave to be specific one? I need one for projects like wireless induction, laser tripwires etc. I would really appreciate it if you could help. Thanks in advance -Prickly Potato

Asked by The Prickly Potato 3 years ago



NO/NC? Answered

This was enlightening. So is it safe to describe a NPN as normally open, until current is applied to the base and it closes,and PNP as normally closed, until current is applied to the base and it opens?

Asked by adillbeck 1 year ago


Substitute of Power Transistor

What is the substitute of 2N6292 power transistor? Please suggest a good substitute of 2N6292.It must be an NPN power transistor. Thank you.

Asked by SiamB1 1 year ago


how exactly do transistors work? in detail.? Answered

 i need to know about how applying a positive charge to the base allows electrons to flow through it to the emmiter. npn

Asked by 2tautges 8 years ago


Will this 'switching' circuit work for cabinet lights? Any comments?

Im making cabinet lights using LEDs. I use a transformer to power it off AC mains, but I want it to run on batteries too... So Im making a circuit that would automatically change the source of the power from the mains to battery when the power goes out, and back again when it comes on. Im using an NPN and a PNP transistor to do the switching. When mains (S1) is on, the NPN is on and current flows from the transformer, when S1 is off, NPN is off and PNP is on and current flows from the batteries. What I am worried about is that (I think) the transistors need a Gnd on the emitter. Is that right? If I connect the +ve of LEDs to [OUT] and -ve to GND will it work as expected? Can someone try please?

Asked by pro2xy 6 years ago


How to control more positive current using microcontrollers?

Most microcontrollers can directly control low current  at +5v. Using NPN transistors I can control higher currents, but now negative. My question is: how to switch more positive current (>40mA) than my microcontroller can do directly? The obvious idea is to cascade a PNP to a NPN transistor, but aren't there ICs ready-made for it? More or less like UNL2803A, but using Sziklai arrays instead. What would otherwise be the "standard" way of doing it?

Asked by eshneto 8 years ago


Resistor for NPN Transistor Base? Answered

Hey all, I need help identifying the value of the resistor I would need for the base of a 2n2222a transistor in this circuit. If you need any additional information, ask and ill try to answer asap. The resistance of the relay coil is 106 ohms and its rated for 6v but I operate it at 5v. The 3.3v is supplied by a step down circuit connected to the same power supply as the 5v used to operate the relay. If you can, please also list the steps you took to calculate the value of the resistor so that it can be useful for future use, I couldn't find a simple answer online. Ty,

Asked by SA-DIY 8 months ago


HELP: Blinking light circuit ( Music Synced)

Hi I'm trying to build a music synced blinking light circuit. However I AM A NOOB. I don't know almost anything about electronics and stuff. But i'll manage. So the first problem is that I cannot get tip31 or any tip transistors in the market. All I have is BC547 NPN transistor or 2N2222, General Purpose NPN Signal Transistors ( TO92 ). And I wish to attach blue led strip in the circuit. and will be powering the circuit using 12v power adapter. Please suggest how much of Amps should it be of. A diagram of it would also help :) Thanks in advance!

Asked by vmahajan3 3 years ago


Witch transistor should i choose for low noise audio ? Answered

Hello , im making a guitar pedal .The original schematic use transistor BC107B (epitaxial NPN) but i dont have it.so i find some other NPN transistor to replace it. I have 2N3903 ,2SC1815,2N3904 , but witch should i choose for low noise application ? in their datasheet i found the "NF : noise figure" , the lower NF mean lower noise ?? BC107B         NF  Typ.= 2  Max.= 10 2N3903          NF  Typ.= -  Max.= 6 2N3904          NF  Typ.= -  Max.= 5 2SC1815       NF  Typ.= 1  Max.= 10 Thanks for advance! sorry for my bad English.

Asked by login721 6 years ago