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)
2
votes
1answer
261 views
What is the function of a MOSFET driver in an H-bridge?
What would happen if I didn't use MOSFET gate a driver, and simply connected the MOSFET gates directly to the logic outputs of a microcontroller? I am quite confused about the need of a MOSFET driver.
...
4
votes
1answer
162 views
Transistor-saturation state
I've a doubt in the working of transistor...
In a Common Emitter transistor(n-p-n), at the saturation state(when collector current maximum), both the junctions are forward biased...well then how can ...
4
votes
1answer
172 views
how to design a switch which works when an input of 0.10 is applied
i have an alarm clock , it's output voltage to the alarm buzzer is around 0.15 volt ,
i need to attach an electrical appliance to make it operate on scheduled time ,
for that i had used this circuit ...
7
votes
1answer
113 views
What does O stand for in V_CBO and V_CEO?
I have just bought this transistor. In the absolute maximum ratings, the voltage names end in O, such as V_CBO, ...
2
votes
2answers
188 views
LED tachometer with PIC MCU (requires more current)
I've been working on an LED tachometer that will be installed on an open wheel race car. After putting the order through for the PCB I re-calculated the current draw and turns out the PIC's (16F877A) ...
4
votes
1answer
369 views
Arduino Uno with 12V pump: transistor or optocoupler+12V relay?
I'm not a real expert in electronics but I'm going to start a new project that has completely captured me.
I need to drive a 12V pump with my Arduino Uno. The pump is "Dp0102" (12V, 0.7A). To power ...
20
votes
5answers
832 views
Why would one drive LEDs with a common emitter?
I've seen tutorials aimed at beginners suggest the way to drive an LED from something without enough current drive is this:
(option A)
but why not this:
(option B)
Option B seems to have some ...
7
votes
1answer
1k views
Can the Common Emmiter Amplifier use a PNP Transistor instead?
This is a simple Class A amplifier using an NPN transistor:
Is there a way this can use a PNP transistor, instead (with only 0V and +Vcc, not 0V and -Vcc)? Why or why not?
1
vote
4answers
288 views
Very Basic Electronics Question regarding current flow
This would be considered a basic electronics question that I should know (I've been all over the place with questions tonight and I apologize).
But anyways using this circuit (It's a TTL SR latch)
...
-2
votes
1answer
148 views
Design of a system to measure the speed of a falling simulated raindrop
I would like to know if using an IR emitter and a photo-transistor would do the job. Here are the specs of the photo-transistor.
Also I'm using the Arduino Uno board; any tips on how to program it ...
6
votes
2answers
370 views
What is the reason this USB battery charge circuit will not work without a diode?
I have a single cell, ~2100mAh rated Li-Ion battery. Something like 18650, I have taken it out from a laptop battery pack. I want to make a simple charging circuitry for it since I will use it in the ...
3
votes
2answers
1k views
Building a relay circuit for the Raspberry Pi
To start
I have only a cursory knowledge of electronics... I "know" what all the basic components do, but I have not figured out how to use that knowledge to design anything (much less evaluate ...
5
votes
2answers
125 views
Datasheet term for transistor power consumption when OFF?
I'm trying to find a transistor that can power up to 1A (1000mA) on an animated LED strip lighting circuit. From this thread I found the BC517 darlington:
Choosing the right transistor for a ...
2
votes
1answer
50 views
Darlington (TIP110) gain value
I'm referencing this Fairchild semiconductor datasheet on the TIP112. (I'm actually working with a TIP110) and trying to evaluate the gain. In the specs grid on the second page, the sheet states -> ...
4
votes
2answers
329 views
Why won't my 2 x NPN circuit latch?
I'm working on building a soft-latch power switch. Before I build the entire thing, I'd like to ensure that I can simply latch power on, without adding off functionality. I am wondering why the ...
0
votes
2answers
127 views
Date of introduction of TO-92 transistors
I'm trying to date a circuit from an organ. It contains transistors in a TO-92 (plastic) package.
Approximately when did these transistors first appear?
3
votes
1answer
81 views
Connecting a N.O. grounded switch to a scanning switch matrix
I am working on a project that includes a scanning switch matrix. It also includes a joystick with an integrated push button. I am out of IO pins on the micro, but there are gaps in my switch matrix, ...
4
votes
3answers
149 views
Whats the role of these transistors
I'm asked to explain what the function of transistors Q1-Q2 and Q3-Q13 are.
So far i've been unable to figure it out. If you know what the functions are, please also tell my how you derived it.
3
votes
1answer
515 views
Using a TIP122 to control a motor
How do I control a hobbyist DC motor with a TIP122 transistor?
I want to control it with the Arduino PWM pins, the power supply is 4 1.5V AA batteries connected in series giving 6v.
Also, what steps ...
21
votes
1answer
435 views
Darlingtons, MOSFETS, and bipolar junctions
I realize there are dozens upon dozens of kinds of transistors, each used for specific purposes. Sometimes there is great overlap; multiple kinds may work in a given circuit, but at times only a ...
1
vote
3answers
762 views
how to use a 3v output to control a 5v relay
I have some circuit where my board (Electric imp) can output up to 3.3v,
and i need to control a relay with atleast 5v in order to effect the coil and close the circuit.
i have a power supply of 5v, ...
0
votes
2answers
170 views
Shouldn't the small AC input current in a common emitter amplifier be amplified to DC?
The following image is the circuit of a common emitter amplifier.
The input AC circuit we supply is between the base and emitter. The supplied input is amplified as it can be seen in the image ...
-1
votes
1answer
211 views
Design rules for power AB amplifier stage [closed]
could you please point me to a good guide for a simple class AB power amplifier design based on BJTs (referring to the "classic" schema with complementary push pull, diodes to remove cross over, ...
1
vote
3answers
244 views
what happens when transistors are interchanged in CMOS?
A basic cmos inverter will have a P-transistor upside and N-transistor down side. what happens if we reverse the p and n transistors?
-1
votes
1answer
196 views
Explanation for transistor as amplifier [closed]
Tell me if i am correct or not.
In transistor as an amplifier, we have n-p-n transistor (base in the middle and emitter and collector at the sides). The collector has electrons in majority because it ...
1
vote
1answer
203 views
Depletion Region of a FET
So I finally Dived into understanding the P-N Junction and Field Effect Transistors. (this may almost be teetering on the "Physics portion" of electronics, but it's still mainly for understanding the ...
3
votes
2answers
112 views
Voltage at common node in transistor
This is a rather elementary question but I think my fundamentals are not clear on this. What is the voltage at the common node?
Firstly, I thought voltage was taken across something i.e it's taken ...
3
votes
3answers
344 views
Problems with Transistor TIP122
I was testing some things on my protoboard to learn a little about transistors.
I made this:
The batteries are two AA 1.5V in series.
The resistor is a 1Kohm.
The transistor in a TIP122 npn ...
1
vote
2answers
193 views
How to select a proper transistor?
I've got a schematic that calls for an unspecified "NPN Negistor". From my understanding of the circuit, the NPN is an oscillator that generates two audio tones for testing. Here's the schematic:
...
18
votes
2answers
617 views
Schottky transistor, Not sure I understand it?
So I've been looking through and going through my Digital Computer Electronics book, and I came to this... It seems so simple and I understand the "point" of it, but I'm not sure I understand exactly ...
5
votes
2answers
440 views
Switching a current with an NPN transistor and a P-MOSFET
Just learning about transistors and I'm trying to clearly understand how to apply them for basic switching, in terms of the two standard cases, i.e., Active HIGH behavior and Active LOW behavior. For ...
-4
votes
1answer
216 views
Typical BJT npn transistor - Change 0-5V sensitivity [closed]
What is it in an npn transistor that determines the voltage "maximum" for the base?
because in a typical npn transistor it is 5V, meaning if you feed 5 volt into the base it will flow 100%, 1 volt = ...
0
votes
0answers
180 views
Ring detector circuit, transistors not fully activating
I am attempting to build a ringer interface circuit, and I’m running into problems that are over my head.
The purpose of the circuit is to buffer the output of a central telephone system that goes to ...
0
votes
2answers
71 views
Voltage holder circuit configuration circuit
hi I didn't studies all the circuit configurations and also I'm a newbie to EE.
My question is I need to design something like a voltage holder.
The idea is two emitter followers.
One is NPN one ...
2
votes
2answers
155 views
BJT Saturation Design Point?
I was reading an answer to this other question which asks about saturation of a BJT transistor.
In that answer it states to be saturated you should shoot for a 1:10 ratio or more between base current ...
1
vote
1answer
94 views
Will a MMBT5087 saturate with a 1K resistor in the base?
I am using the configuration in picture and the MMBT5087 PNP transistor. I am not using the top base resistor, just the lower one, so there will be 5V on the base.
My question is: Using a 1K ...
3
votes
3answers
212 views
Polarized capacitors in common emitter amplifier
This is the basic common emitter amplifier.I have read that polarized capacitors should have proper polarity connected to terminals of DC voltage source and they may blow off if they are connected ...
2
votes
1answer
134 views
Physics/chemistry understanding of PMOS and NMOS to form CMOS
Can anyone provide me explanations or links that provide a clear explanation of what atoms/molecules are in p-type and n-type (PMOS/NMOS) and how they interact to create actions?
7
votes
4answers
724 views
How are logic gates created electronically?
So we have AND, NOT, NAND, NOR, OR gates, but how are they created electronically/electrically?
For example, what makes NOT gate reverse the value?
6
votes
3answers
219 views
Tips for Analyzing Circuit with Transistors
Below is a circuit from a homework problem where I am asked to find the operating points of the three transistors. What I need help with is calculating the base currents for the transistors labeled T2 ...
3
votes
2answers
172 views
Can BJT transistors be damaged by static electricity?
I'm wondering whether they should be stored in anti-static bags or not?
3
votes
1answer
217 views
Why amplifiers (RC coupled) are based on voltage divider bias?
What actually determines the type of bias to be used for different practical applications.
Also I do not get the point of using capacitors (coupling) for emitter current and high input resistance. If ...
0
votes
0answers
164 views
Replacement for 5610 Transistor
I have a circuit (from a RC car) that uses a 5610 transistor, which can't find in store.
Is there any equivalent transistor?
Here are pictures of the board (click here for high resolution images):
...
3
votes
1answer
125 views
Advice needed for replacing old ER3055 transistor
I have a transistor in a guitar amp with the label ER3055 that needs to be replaced. I asked about another transistor that I needed to replace in a post a few days ago here and I tried using NTE to ...
1
vote
1answer
109 views
Is it possible that a new transistor is not good even if a current runs through it?
I just got an NTE121 replacement transistor for an old 2N2148 that was in a guitar amp. It was the only part I replaced and now I have no sound coming from the speaker. I checked every component on ...
3
votes
4answers
287 views
Early Effect, Ebers-Moll, Common Emitter Resistance, reverse alpha/beta and saturation current
Ive been reading Sedra/Smith's Micro Electronic Circuits book, and it has a lot of info which I like, however I dont know how much of it is actually practial and useful, for instance it talks about ...
4
votes
2answers
173 views
NPN transistor CE or EC?
hi for NPN transistor normally Collector will be connected with Vcc, resistor then LED.
and Emitter will be conencted to Vss. So whenever voltage applied to base LED illuminates.
however when Vcc ...
4
votes
1answer
181 views
Unijunction transistor in LTspice?
I would like to simulate a simple oscillating circuit involving an unijunction transistor. I do not find such component in LTspice so I figure I need to import one. Could please show me step by step ...
3
votes
2answers
84 views
What is meant by shallow diffusion in silicon fabrication technology
I know this is a google before ask type question, but I didn't find the answer
still on google. Then I went to library and refer some books but my changes were
negative. I've searched more than 20 ...
0
votes
1answer
409 views
Reparing a Chinese power supply Unit
My Chinese phone usb charger has gone.
I opened the lid to repair it, and this is how it looks like (picture below).
Actually how it looked like after I removed Q1 for testing.
I suppose it has ...
