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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2answers
78 views

Switch on computer with microcontroller

I'm making a simple microcontroller based circuit to turn on a computer when certain events are triggered. I am interfacing it using the PCs soft power switch pins on the front panel header: There ...
0
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4answers
56 views

Transistor biasing problem

simulate this circuit – Schematic created using CircuitLab Suppose this is the biasing process of an n-p-n transistor. The battery to the left forward biases the emitter diode because ...
-1
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0answers
95 views

Would anyone explain this circuit? [duplicate]

I know that the transistor works as an amplifier but I can not understand why it is connected this way. I'm a beginner in electronics and I just want an explanation for this circuit (especially the ...
1
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0answers
69 views

Potential difference in a capacitor

As I simulated the circuit below, it shows that the potential difference across Cx is the amount of potential being stored on C3 and C4 during charging phase. How do we get the potential difference of ...
0
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1answer
25 views

Find Id of NMOS

I need to find the drain current in the above circuit where I also know \$V_{TH} = 1\,\mathrm{V}\$ and \$\mu_{n}C_{ox} = 2\cdot 10^{-4} \frac{\mathrm{A}}{\mathrm{V}^2}\$. I'm just not sure about ...
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1answer
61 views

Using transistor as switch with low voltage

Basically, I need to monitor a circuit's output so I can activate another system. The output voltage of active stage is 140mV. If I am not wrong (from what I read about transistors) 140mV is not ...
0
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0answers
33 views

How to calculate current boosting ratio in CMOS technology

In the following picture: The \$I_{out}/I_{in}\$ equals \$(1+C_2/C_1)\$. But I can't calculate it. \$I_{out} = g_{m}\cdot V_{GS}\$ for MOSFET \$\text{M}_2\$, but how to find out the voltage of ...
0
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1answer
77 views

Two-stage amplifier

This is my first time designing a circuit by myself :) The input of this circuit is the output jack of my MP3 Player. The output of this circuit is 4-Ohm loud speaker (sometimes I connect 8-Ohm ...
0
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1answer
60 views

Compare the MOSFET and LDMOSFET [closed]

My major is not electronic, but I really really need the answer of this question: Compare the MOSFET and LDMOSFET. Since my major is not electronic, I have searched what is MOSFET and what is ...
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2answers
72 views

How to choose a transistor for amplification

I've been trying to find information on choosing an NPN transistor but everything I've found seems to apply to saturated transistors only. I'm basically trying to amplify the current given from a 3mm ...
0
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2answers
56 views

How to identify SMT transitors

im trying to identify the following 4 transistors, but am having trouble tracking them down. The one that I think is the dual transistor is marked .1Ft on top of it, and the other three leg one is ...
0
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0answers
38 views

2 Transistor 2:1 MUX with negative waveform

My PTL(Pass transistor logic) 2:1 mux show -ve waveform at at some inputs combination ckt and waveform show below: simulations perform at 180nm tech, 250mhz,1.8v power supply. How to cope this ...
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3answers
50 views

Question about common emitter configuration?

The configuration of the common emitter amplifier is one resistor at the emitter, on resistor at the collector, two bias resistors at the base as shown in this picture : I saw this new ...
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3answers
90 views

NMOS: why VGS instead of VG?

I am having lots of trouble trying to understand how the mosfet is triggered. The text I read assumes the source of the NMOS connect to ground, while a positive voltage is applied at the gate. ...
1
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1answer
101 views

Would you help me understand this simple circuit?

I have three questions: Is it common emitter or common collector (emitter follower) or something else? How do you recognize it? What is the function/usage of R1 and C1? Are they for biasing the ...
1
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1answer
75 views

Deciding base resistor for transistor switch circuit

I'm building a transistor switch circuit and below is the schematic. simulate this circuit – Schematic created using CircuitLab I calculated R2 resistor (base resistor) value from this ...
0
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3answers
59 views

Motor controller - transistor taking up 3/4th of the voltage

I am trying to make a motor controller for a DC brushed motor. The design is fairly simple, see below - motor represented by inductor The problem I am having is that if we imagine A to be HIGH and ...
0
votes
1answer
64 views

Can I use an N-MOSFET to turn off a voltage divider?

I'm using a simple voltage divider to measure the voltage of my battery. The battery will be in the neighborhood of 12V, and the uC runs at 3.3V. I don't need to read it often, and don't mind a few ...
0
votes
2answers
62 views

BJT at saturation

Considering a npn transistor, when it is active the electrons at the base (which came from the emitter) is swept into collector as the collector is at a higher voltage level. In case of saturation, ...
5
votes
1answer
44 views

Positive Photo Resist for lift-off & Negative for EBL?

I would like to know two things about Photo Resists (PR): How is positive photo resist used for lift-off? What is EBL and why negative photo resist is used in this case?
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1answer
62 views

Transistor Isn't Forming the Connection

I have wired the following diagram. simulate this circuit – Schematic created using CircuitLab My understanding of transistors is relatively poor, and thus I am assuming it has to do ...
3
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2answers
59 views

Using NPN Darlington to switch on PNP

I'm trying to separately switch on the digits of a 2 digit common anode 7 segment display (specifically the Lumex LDD-E2802RD because it's small and cheap). I think that the easiest way of getting my ...
1
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1answer
122 views

Arduino crashes switching 230V relay OFF

Here is my circuit schematic : I need to power ON/OFF a 230VAC fan using a relay. The relay is powered by a 5V DC power supply. Digital pin on the Arduino board open or close the circuit in PNP as ...
2
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3answers
371 views

Creating led sequence without microcontrollers

I'm new to electronics and I can work only with transistors. I'm trying to create a circuit that performs action like this: Let's say I have 10 LEDs. When I supply power first LED lights, 0.5 sec ...
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2answers
45 views

What are the selection parameters for an NPN BJT?

I'm building an NPN-based driver circuit for disconnecting my battery level measuring voltage divider when not in use. Here's the circuit: ...
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0answers
63 views

BJT Circuit DC Analysis

I am trying to find the collector's current of each transistor in order to find the transconductance gm of both, but I don't know how to relate the currents of them. There's any approach? Thanks
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1answer
69 views

BJT Transistor question help here?

We have the BJT transistor in the figure. I have to do the DC analysis of the circuit, then draw the common base transistor scheme of the circuit. I know the values of \$V_{cc}\$, \$V_{be}\$, ...
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3answers
100 views

Last resort debug: Voltage limiter

Note: This is a followup to a previous question that was left unanswered. The circuit has been remade on a breadboard and the symptoms are different I have been trying to make a voltage limiter ...
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2answers
132 views

how to choose resistors' value for common emitter amplifier? [closed]

I want to choose the best values of R1 , R2 , R3 and R4 to get the maximum gain (high performance). I design the circuits practically, so I don't need to do a lot of calculations. I want the ...
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2answers
191 views

What are some good representative transistors for a beginner's electronics class? [closed]

Context: assembling coursework for a beginning electronics class. There are various kinds of transistors commonly used in electronics circuits. What kinds of transistors would be useful to include ...
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1answer
49 views

Which one of these transistors is equivalent to 2N918 NPN?

This is an FM radio receiver. Q1 is 2N918 NPN transistor but it is not available for me. Which one of the following transistors is more equivalent to Q1 ? BC547 TL431 s8550 s9014 2n5401 ...
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3answers
148 views

Control voltage using transistor

I know nothing about transistors except they can be used as simple amplifiers. I do not know which one to use for my project. A port from arduino would give me volts ranging 0V-5V. I have an external ...
2
votes
4answers
228 views

What is the collector-emitter resistance of NPN Transistor?

the question may look ridiculous since I'm not sure if the collector-emitter resistance exists or not. Here is a simple commom emitter circuit As I learn that when the Vb increase that will make Ib ...
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2answers
85 views

Switching an LM317BTG on/off using a microcontroller

We're using an LM317BTG to power a 4V modem (the LM is connected to a 12V battery). The modem can produce peak currents of up to 2A during transmission bursts. Under normal operations, the modem ...
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0answers
42 views

Vintage Motorola Part Identification

I found a box of 1970 vintage Motorola transistors (at least they look like transistors). I can't seem to find any data on these. Any help is much appreciated. On the box it is labeled type SS3071H. ...
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3answers
142 views

What is the component in bluetooth module

Last month, I bought a bluetooth audio module on eBay. And I wonder what components are on this PCB. In the picture, what is the component in the top red box? What is the component in the bottom red ...
2
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2answers
186 views

Learning transistor based circuits

simulate this circuit – Schematic created using CircuitLab In one of our electronic circuit tests, this question was asked: What is the output voltage of given circuit? This circuit ...
0
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1answer
130 views

Two way switch using transistors

Friends, I am very new to electronics and I am trying to design a simple switch with a transistor. Following is the circuit: The input is a square wave generator with positive and negative cycles ...
29
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8answers
5k views

How can “purely” electrical circuits emit sound?

Moving membranes or piezoelectric materials obviously produce sound waves, but how can "purely" electrical circuits such as transformers or DCDC choppers (and others) often have an audible noise? Is ...
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3answers
73 views

Connecting diodes to a motor in H-bridge

I'm attempting to design a three wheeled toy that is controlled by a remote connected with it via a cable. I first designed it with relays, however I had to change to transistors due to contrast ...
2
votes
1answer
109 views

Specification Clarification for FETs

I use a MOSFET in my project, and I don't know what model of MOSFET I need. I do have a list of specs, but I don't know what they would be called on the datasheet. I need some help translating my ...
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2answers
52 views

PMOS, NMOS length width concept for low power circuit

Why for low power consumption width of NMOS taken same as length of feature and Width of PMOS taken as 2.5 times width of NMOS ? e.g for feature size 180n width of NMOS 180n and width of PMOS 450n. Is ...
0
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3answers
84 views

How can you calculate base voltage of a transistor when there are biasing resistor and a resistor between 2 input terminal

I just get to know about transistor a little. Here is my question As you can see that here the transistor is configured to be an amplifier in common emitter mode. R1 here is the bias resistor. What ...
0
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1answer
56 views

Load cell without In-amp

I have a 0-1kg load cell with 4 wires: Excitation + and -, and Signal + and -. I haven't had any problems wiring them up correctly without amplification, and my voltmeter shows me a 1 mV difference ...
4
votes
4answers
563 views

AC equivalent circuit of transistor

For AC equivalent circuits, it is written that, in the case of small input signals the emitter diode does not rectify, instead it offers a resistance called AC resistance. Why is this so? Why doesn't ...
0
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2answers
78 views

Photo-Interrupter Usage

One of the projects I am working on requires a number of photo-interrupters to be used. I was wondering if someone could explain how to use them correctly? I was thinking something like this: ...
1
vote
2answers
85 views

common emitter problem

I have this problem to solve where I1 = 6mA, beta=125 and Vbe =0.6V So far I have solved the following, a. How circuit works? Circuit works as a stable output voltage source. This is caused by ...
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3answers
116 views

Output impedance refers to open circuit o/p impedance or short circuit o/p impedance?

When we specify output impedance of a two port network, does it imply open circuit output impedance or short circuit output impedance? Wikipedia: output impedance ; Wikipedia: two-port network g22 ...
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2answers
94 views

Using a DC voltage as the base for a transistor to amplify AC Voltage

I'm a little new to electronics, particularly transistors, so I don't know a lot of the different types and inner-workings of them. I have a diagram which, hopefully, will gradually increase the ...
1
vote
1answer
87 views

2 Transistor XOR Cell Floating Output Problem

I designed the following 2T XOR cell for my full adder purpose: Theoretically it gives correct output for all input combinations. But on Tanner Eda using 180nm technology 5V supply, it gives logic ...