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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Why doesn't a capacitor connected to a MOSFET charge to VDD

If an nmos which has the gate and drain connected to VDD, and the source connected to a grounded capacitor, the nmos will start conducting and the capacitor will start charging as long as VDD > VTn ...
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23 views

Cadence, BSIM3V3, and the Body Effect

I am trying to meet the compliance/min output voltage of a wide swing current mirror so the output current (10uA) is within .1% or +/- .01uA. I am using Cadence and ami06 nFET's to do so. I am always ...
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28 views

Measuring the output of a phase control triac

I have an air compressor I'm trying to troubleshoot and I'm trying to determine if the problem is with a small circuit board with a triac. The board takes as input an ac wall outlet (US) and outputs ...
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2answers
106 views

Capacitor between emitter and collector

What is the purpose of capacitor C5 ? I know it provides positive feedback to sustain the LC oscillations, but how does this work ?
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31 views

Design of ALU use both PTL and adiabatic Logic

Adder module of My 4 bit ALU use 6 Transistor PTL circuit,to reduce power consumption. For further reduction in power consumption can I use 2:1 and 4:1 adibatic mux or there is some kind of ...
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96 views

Why can I have the positive and negative at the base of a transistor at the same time?

I am reading/doing the make electronics book and I am having a hard time in understanding how is it possible to have the positive and negative poles connected (even with a resistor) to the base of a ...
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85 views

BJT base resistor

I read this post: Which resistor for NPN transistor base? But I still cannot understand the base resistor calculation. I need the transistor to be a switch to 5V 200mA relay. The base will get its ...
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2answers
118 views

Transistor to run relay

In addition to my last post I have more information and details. I want to run 240V Relay (5V Coil) from my AVR chip (ATmega328P). My EMR relay takes up to 200mA on it peak. I have 2N2222 ...
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2answers
56 views

Reduce effect of supply voltage on pulse stretcher

Considering the following simple pulse stretcher, how can I reduce the influence of supply voltage on the pulse length? simulate this circuit – Schematic created using CircuitLab I ...
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2answers
79 views

Transistor rating with capacitive load

Considering the following circuit, how do I reliably protect the transistor Q1 from exceeding the collector current rating: simulate this circuit – Schematic created using CircuitLab ...
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0answers
81 views

How to disable a button after power on

Is it possible to prevent button from working when another circuit is on and if it is, then how? To be more specific I'll try to describe what I'm trying to achieve. Basically there's two independent ...
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43 views

Need help with design of level shifter [2 vdd, 2 gnd]

This is the first time I've run across a system design with these requirements and it has me stumped. I need a level shifter made of smd discrete components capable of shifting SPI SCK and MOSI ...
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1answer
63 views

Need a transistor to drive 12v 400mA Solenoid

I need a transistor whose base will be driven by a controller (3mA max base current). the Vce(sat) should be less than 0.5 or max 0.7. And collector current required by solenoid is 400mA. I am unable ...
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57 views

Looking for a transistor to power a load with PWM from a Bluetooth module

My project is a heating load power with a PWM from a Bluetooth module (BLE113). I managed to do the PWM I want with this module and now I would like to connect the load. The module give a PWM with ...
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2answers
56 views

How to steer 20v from ATmega pin?

I want to enable/disable 20V current with my ATmega pin. How can I connect transistor and what transistor?
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1answer
58 views

Input impedance of a transistor amplifier from an example

Going on reading "The Art of Electronics", I am still stuck on another input impedance calculation for a transistor amplifier. This is really something I should overcome, maybe your explications will ...
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2answers
76 views

Why is the collector voltage must be bigger than the base voltage to operate an npn transistor? [closed]

I'm reading a tutorial on basic transistor operation. It says for an npn transistor to operate such conditions are necessary: VC > VE, by at least a few X 0.1V VB > VE VC > VB We do not exceed ...
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55 views

Thevenin equivalent of a transistor

I get the idea of how to calculate a Thevenin equivalent, but I'm having troubles applying that for transistors. In "The Art of Electronics" from Horowitz & Hill (2nd edition, p66) the input ...
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28 views

Convert Analog Based Full Adder Circuit into CMOS Based circuit?

I am working on PTL(Pass transistor logic) ALU for improvement in dynamic power i reduce transistor count from 8(Traditional Design ) to 6 for its adder module. assume transistor as ideal one.circuit ...
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3answers
61 views

Common emitter amplifier

Common emitter amplifier gives an amplified inverted output. So if I fed the inverted output to a speaker, would it sound fine ? If not, how do I get an amplified but non inverted output from a common ...
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3answers
70 views

Voltage dip on MOSFET switchable current shunt

I have the following circuit built up in LTSpice which will be used to switch in different sense resistors for current measurements. The mAEn signal switches the M1 transistor on at t=10ms which ...
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1answer
36 views

TO-18 case connected to device?

I'm seeing some weird behavior in a circuit I just soldered up. I haven't done detailed debugging yet, but it occurred to me that the metal case on the 2N2222A transistors I used might be connected ...
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3answers
317 views

Transistor and Resistors [duplicate]

What is the function of the two resistors arranged in parallel with the transistor? Do they also limit the current to the transistor? The full circuit is this:
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41 views

TIP122+Arduino didn't turn on the light! [duplicate]

Basically i'm building a simple circuit to build up till i get a light dimmer. The following circuit is an attempt to get the transistor working as a on/off switch. Whats is happening is that the ...
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131 views

Simple FM transmitter [duplicate]

How does this circuit perform Frequency modulation. I know the LC generates the carrier frequency. How does the transistor act as a varicap to perform FM. Which part of the circuit acts as a varicap ...
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3answers
484 views

What determines how much current can flow through a 2N2222 A?

I've been fiddling around with a brushed DC motor, a 2N2222 and an arduino's PWM to get different speeds out of my motor. Now, based on a video tutorial I watched on youtube, It was recommended to put ...
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57 views

how to calculate Ic as the current through the collector and function of the transistor

I am going through this tutorial, they state that "Ic is the current through the collector and function of the transistor" however I haven't really been able to look at the data sheet and figure out ...
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5answers
182 views

Override digital out with pushbutton

I have an Arduino Digital Out pin connected to a 1k resistor, then connected the base of a 2N3904 transitor. In fact, that same digital out is connected to several resistor->base-of-2n3904. Each ...
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3answers
94 views

Choosing “widespread” parts

Many times I know the parameters of a part to choose and find hundreds of them, but I don't know which ones I would have to order, which ones I am likely to found in a local electronic parts store, ...
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50 views

How to get better output out of flyback driver?

simulate this circuit – Schematic created using CircuitLab I used this circuit to power my flyback... I used an MJE3055T Power NPN and 10kOhm pot. The flyback is FKD15A001. I used the ...
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2answers
710 views

Simple electrical circuit won't work

Simple NPN switching circuit to open a relay circuit, first NPN switching part didn't want to work (3rd PCB and endless times of trying). Circuit wizard diagrams, I split its first part to figure out ...
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5answers
78 views

Use transistor to connect terminating resistor for differential signal?

Is it okay to use a transistor to connect a terminating resistor between the A and B lines of a differential signal? I'm not sure because I know that at the source/emitter of an NPN transistor must be ...
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1answer
83 views

Choosing a transistor to Relay

I am building new project, which I will power up the water tank heater from my smartphone. I have few safety though I want to ask here to get your opinion. I am going to use AVR to run a relay, that ...
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2answers
368 views

How do I make an LED turn on when my output reaches 5v?

I'm a hobbyist and pretty new to many of the components involved, so I hope you guys can help me here. I'm trying to keep the circuit as simple as possible. I made a small variable power supply with ...
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3answers
91 views

Switching LED with a transistor

I would like to switch a 350mA LED with a transistor. Switching is done by a 5V microcontroller and the main voltage is provided by a 24V power supply. To play around and see what works I used Yenka, ...
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1answer
81 views

2 transistors in solar charging circuit

I don't quite understand this circuit. Why are there 2 transistors? Wouldn't 1 transistor be enough? The blink LED triggers the first transistor every time it blinks. But, how I understand it, the ...
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3answers
192 views

Input resistance of a transistor circuit

I have a question from the razavi's microelectronics book: I'm puzzled because in the solution provided, the first line states that: "We know that the input resistance Rin = R1||R2||\$r_π\$." ...
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183 views

Can I replace a 2N222 by a BC558B, BC549C or BC327?

I just started studying Arduino and I'm watching a online course. I got into the stage where we're suppose to build some sort of protection system so we can plug-in outsourced power supply and prevent ...
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2answers
96 views

BJT vs MOSFET failure modes

I know MOSFETs are much more efficient than BJTs in that they don't consume as much power when on whereas a BJT consumes base current the whole time it is on. I also know that MOSFETs tend to fail ...
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1answer
181 views

What components are these?

I usually buy electronics components at an online surplus store and they usually throw in the box some more goodies to pack what you order. I bought a multi section plastic contanier and it was ...
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3answers
543 views

Micro, MOSFET and DC motors

I'm developing a nano quadcopter using an Atmega328 microcontroller, powered at 3.3V, and very small brushed DC motors. The average current used by these motors is about 800mA @ 3.7V. Initially, to ...
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2answers
78 views

Howland Current Pump VS Wilson Current Mirror

I am interested on knowing what would be a better solution to create a current source for low current applications (below 20mA), an opamp based current source such as a Howland current pump (link to ...
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1answer
83 views

How to calculate maximum allowable signal swing at the collector?

How to calculate maximum allowable signal swing at the collector? How does change in beta value change the swing at both ends?
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2answers
145 views

Is a N-Channel Mosfet save/reliable for level shifting UART from 3V3 to 5V?

I am busy with a design that needs to connect a Raspberry Pi to an Arduino via UART. Previously I have designed a circuit that worked okay. But now I want start using SMD components and is planing ...
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1answer
104 views

PIC programmer, need to replace few components

I am building a PIC micro-controller programmer named Brenner8: http://www.sprut.de/electronic/pic/projekte/brenner8/ Although, it needs a BF959 transistor for (Q8), and BAT43 diodes for (D1,D2,D4) ...
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1answer
109 views

Are BJTs used in modern integrated circuits to the same extent as MOSFETs?

On modern integrated circuits, are there as much BJT's on the chip as MOSFET transistor? If not, why?
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1answer
97 views

Why is BJT scaling not as significant as MOSFET scaling?

When reading about integrated circuits, MOSFET scaling comes up very often, however BJT scaling is never discusses. What's the reason for this?
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1answer
106 views

Simple transistor for switching a computer power supply

I am teaching myself about simple transistor circuit design and have been stumped by the simplest transistor behaviours. The task I have set is to use a transistor to switch on an ATX computer power ...
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2answers
117 views

Why do I need a transistor to control a relay with an arduino, and which one should I get for this circuit?

I need to control a coffee machine plugged into a wall outlet using a relay connected to an arduino. Apparently I need to connect a transistor to the relay. Why? Is it because the arduino can't supply ...
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3answers
60 views

Can we minimize the no of transistor by using Transistor connected as a diode [closed]

I need to know the advantage and limitation of a transistor connected as diode. In a paper which i ref..its existing level shifter circuit consist of 17 no of transistor(CMOS) and this shift the ...