The transistor is a semiconductor device that can amplify signals and switch power. Most used types are bipolar (BJT, for Bipolar Junction Transistor) and MOSFET (FET, for Field Effect Transistor)

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Floating Collector

I am working on a project where power to the 5VDC supply to a micro can be interrupted during operation (by user). I need to signify to the micro that it is about to lose power so it can perform ...
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1answer
57 views

How do I build a NAND Gate? [on hold]

I dont have enough components and equipment to build circuits so im using Autodesk Circuits. I was wondering how to build a NAND Gate with transistors (I dont know whether NPN or PNP), I know how the ...
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2answers
140 views

The Art of Electronics, figure 2.10B

I'm trying to learn electronics and right now I'm reading the book The Art of Electronics. I'm stuck on this chapter 2 on figure 2.10B. In particular I'm simply confused with the lingo like "...
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3answers
66 views

Sedra and Smith Microelectronics 7th edition Example 6.12

I quote from the book: "By examining the circuit, we conclude that the two transistors Q1 and Q2 cannot be simultaneously conducting. Thus if Q1 is on, Q2 will be off, and vice versa." Assume β = 100....
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1answer
125 views

Decoding Transformer circuit for power supply generation

I am referring below schematic of transformer to generate power supplies in the system. Transformer used is step up transformer (Input-5V, Output: +/- 12V, +/- 48) But I am not getting how ...
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0answers
37 views

Running a fan off minimal solar power [on hold]

I need a little help. It has been over 30 years since I last was in a high school electronics class. I have forgotten much. I have a solar panel. I found that in low light levels I can use it to ...
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1answer
108 views

Designing Discrete differential inputs Amplifier [closed]

I am trying to analyse a discrete differential amplifier circuit by answering some question. I have done the analysis of the input stage, I would appreciate if I can get some feedback on my approach. ...
3
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2answers
64 views

Multi level logic in transistor level. Possible?

I am currently studying the MOSFET transistor for Digital CMOS IC design. There, the noise ratio is defined and the 50% margin is assigned for a logic HIGH and LOW. Taking the noise into account, do ...
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2answers
67 views

Correct resistance for a transistor?

How do you know what R1 should be to completely turn on the transistor? simulate this circuit – Schematic created using CircuitLab
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4answers
87 views

Connect LED from audio output without it blinking?

I have a circuit in which I want a pre-built stereo amplifier kit (with + and - outputs for each speaker) to drive a speaker and an LED in parallel. The circuit works, however is there any way to stop ...
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1answer
87 views

Music reactive LEDs [closed]

I want to make a bigger project, but I have run in to a problem that I do not understand. I want to make an LED flash to music, for use in a bigger project. I have looked at about 20 different ...
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1answer
42 views

Connecting Cathod Commond RGB Leds in parallel with arduino

I'm just starting with arduino, and want to light up 2 RGB leds (common cathode), and just think that the only thing I nedd was connecting them in parallel, no extra parts (my mistake), then I read ...
-1
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2answers
71 views

Turning on a 5v circuit with an 3.3v control signal (from a Raspberry PI) [duplicate]

I want to run a NE555 timer in astable mode, but I only want it to turn on when a 3.3v is supplied, I want to make use of a transistor to do the switching. At the moment i am using a 2N2222 ...
3
votes
1answer
137 views

Odd NPN Circuit behavior

I've seen lots of useful threads here over the years but this is my first post. I'm building a little box to switch an output based on RPM's watching the ground of an the primary ignition coil on an ...
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1answer
58 views

Light dependent resistor (LDR) switched LED-circuit

NOTE! The LDR has a minimum val = 2kOhm and a max. val. = about 5 MOhm Im trying to build this circuit for my radio station. I would appreciate som help. Your general opinion about the ...
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1answer
106 views

How does this optocoupler work? [closed]

I am working on an embedded system and unfortunately I have not got a proper schematic for checking power failure. However, I have a PCB for that so I drew a schematic based on the PCB. I just ...
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1answer
67 views

Use Transistor As Mosfet [closed]

I want to make mazilli ZVS Flyback driver based on this tutorial www.instructables.com/id/ZVS-Driver I needed IRFP250 mosfet for making it I cant find it locally.In the schematic picture they said ...
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1answer
94 views

Which circuit is more Stable?

The circuits in the picture are basically opto-couplers connected to a relay circuit. The input pin of the opto coupler is connected to a MCU and the output of the opto coupler is connected to the ...
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2answers
91 views

How the transistor works in this 555 circuit?

555 Is not able to provide long timing due to its leakage current. The following circuit is very useful to build a long time timer such as 1 hour or more. The accuracy of the time is not important ...
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4answers
289 views

What's the differences of these usage of PNP, NPN transistors?

I am reading the book Electrical Engineering 101. When talking about NPN and PNP transistors, the book said this: Use an NPN to switch a ground leg and a PNP to switch a Vcc leg. This might ...
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0answers
98 views

Simple resistance based water sensor works in stagnant water but blows out in running water, under faucet

The circuit is intended to flash an LED every 7 seconds when there is no water and to flash it very rapidly (time period less than 1 second) when it "senses" water. It all worked well when tested with ...
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0answers
62 views

Why does my MOSFET output depend on source-drain bias sweep direction?

I measure my MOSFET at fix gating voltage (on-state). When I sweep source-drain bias from 1 V to 0 V, current decreases from \$10^{-6} A\$ to \$10^{-12} A\$. But when I sweep source-drain bias from 0 ...
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2answers
423 views

Electronic components without rust or corrosion

Is there any sort of special conductive material that doesn't rust or cause corrosion?
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2answers
152 views

Why do simple H-Bridges that use PNPs combined with NPNs not short themselves out immediately (or do they)?

There is a simple design for an H-bridge that I keep seeing all over the place. simulate this circuit – Schematic created using CircuitLab This design is featured on the Sparkfun ...
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1answer
76 views

Transistor with S250 marking

does anyone knows what type of transistor this is: DGS S250 PH1d Thanks in advance, Pedro
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41 views

NPN Transistor BE & CE flow?

When it comes to using a npn transistor as a switch that controls anything running off of a different power supply. Is the most important thing to keep in mind the difference in current between the BE ...
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56 views

Why does the collector current direction remain the same in saturation and active region?

The collector current direction remains same in both active and saturation state where the former puts the base collector junction reverse biased and the latter puts the base collector junction ...
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3answers
120 views

How would vacuum tube logic work?

I was recently reading up on vacuum tube like devices that could serve as a possible replacement for traditional CMOS technology. How could vacuum tube like technology replace CMOS if vacuum tubes don'...
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1answer
46 views

isolated high voltage H-bridge

I want to control on isolated H bridge that powered with 100V and can drive up to 0.5A low frequency 3HZ but Pulse width of 200uS . the response times should be is US so i cant use Solid State Relay ...
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3answers
136 views

Why is saturation region called so in BJT characteristics?

I understand base-collector (current) linear relationship is lost in saturation region and collector current will be lesser than \$ \beta * Ib \$ . Hence,at max, we can call such a region as non-...
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20 views

Best transistor to power a 12 volt tesla pancake coil

I have made a tesla pancake coil consisting of 47 feet of 18 gauge speaker wire. Wish to power it with 12 volts DC using a single NPN transistor and a base resistor. What hi voltage switch type ...
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1answer
62 views

How to Build slayer exciter

i am trying to make a slayer exciter .i am using this diagrm http://www.instructables.com/id/How-to-Build-a-Slayer-Exciter/step2/The-Driver-Circuit/#step1 but I used components like TIP36C(PNP),5oo ...
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1answer
45 views

What characteristics of a MOSFET should I be looking at? [duplicate]

I'm trying to determine a MOSFET for a circuit I'm building which will drive the gate of an N-channel MOSFET at 3.3v with an available current 40mA (**this will be driven using PWM at 4MHz), the ...
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1answer
41 views

MOSFET Replacement for PNP BJT in a 12V switching circuit

I used a PNP to control 12V in circuit. as follows System_Load/2 is 12V DC, MIC1_PWR is the output and LCD_W2/1 is the control signal. This circuit would work fine if the control signal's High is ...
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1answer
82 views

Current limitations of a MOSFET [closed]

I am using IRFZ44N for supplying current to the RGB LED strip. The current that is supplied by the three MOSFETs for the three corresponding colors (R-G-B) is not uniform and much less than required ...
2
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2answers
343 views

What is Full form of hFE of a digital multimeter?

In digital multimeter, there is a transistor-check function, and there is a term hFE. I do-not know how-to use-it, however, different Websites say it is a measurement transistor's gain ("the ratio of ...
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3answers
218 views

What is a weak transistor?

In implementation section of C-element at Wikipedia website: https://en.wikipedia.org/wiki/C-element there is a diagram that points to a weak transistor. What is a weak transistor? Below is the ...
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1answer
43 views

Energy band diagram

simulate this circuit – Schematic created using CircuitLab My question is if I had an arrangement, instead of a transistor npn, an ipn junction where a i is neutral ,p is p-type semiconductor ...
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1answer
70 views

Falling edge detector using BJT

I'm trying to build what is basically an electronic push button switch - something that would switch an led on an off with the same signal . I figured doing this would require a falling edge detector ,...
3
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1answer
57 views

Transistor level design of flip flops - Is the complementary clock necessary?

Below is one of many different ways to design a Master Slave D Flip Flop. simulate this circuit – Schematic created using CircuitLab Of course a lot of details are glossed over, ...
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2answers
54 views

Simple transistor motor driver does not work properly?

The transistor gets hot to the touch and the motor will continue to run when I disconnect the transistors base from 9v+ (I am trying to make sure the circuit works before I hook it up to an arduino). ...
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2answers
52 views

Motorcycle RPM counter

My plan is to make RPM counter to my motorcycle. I'm planing to read ignition box signal with arduino. I think that ignition box gives 0-12V (or 14.5V max) square wave signal to coil. I was wondering ...
0
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1answer
43 views

Optocoupler 4N25 saturated CTR

I'm studying optocouplers in general, and in special the 4N25. I'm applying the optocoupler in a zero crossing circuit, like this one: I know the CTR is minimum of 20%, but checking the datasheet ...
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0answers
27 views

Controlling motor speed with transistors

I am new to this kind of projects. Want I want to do is to control the speed of a dc motor with an arduino. I saw that you can do this using a transistor, Connecting the transistor to the power source ...
4
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1answer
87 views

Are MESFET transistors still used in the industry?

I was looking for mesfet transistors earlier, because I need some for experiments due to their relatively simple physical structure. I can't find any of these on rs, farnell and mouser ! So I was ...
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2answers
78 views

How to fade or delay a DC Signal to remove speaker “thump”/“click”/“pop” from transistor switch?

I'm trying to create a digital audio switch or relay using an Arduino nano. It's a very simple circuit, it's just a gate (transistor) which is operated by a digital signal (computer) through a ...
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4answers
179 views

Basic Transistor/MCU Question [closed]

Let's say I have 4 AVR MCU's All hooked up to VCC. And let's say they're all connected to ground through an NPN transistor or NMOSFet. Can I use that transistor to switch the MCUs on\off? I'm pretty ...
3
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1answer
174 views

Horowitz's exercise 2.2

Having done the exercise 2.2 from Horowitz's "The Art of Electronics," I feel uncertain and would like somebody familiar with the matter to check my solution. With this aim in head I've searched the ...