A transformer couples two or more AC signals through a magnetic field. Often used as galvanic isolation and to transform one AC voltage to another.

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Full Bridge isolated power supply duty cycle calculation

I'm trying to find out what duty cycle to use for a full bridge power transformer from 180V input down to 5V output. The circuit looks like this without a capacitor across the input: . I understand ...
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4answers
65 views

Any reason I cannot just switch a transformer from a 555 to generate high voltages?

I had an idea to finally start using my nixie tubes and thought why not just switch a mosfet which switches a transformer to generate required high voltages for nixie tubes from a low voltage supply. ...
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4answers
146 views

230 and 240 transformer leads

So I have a transformer that is like 230 || 30 V. One thing I don't get that on primary side it has the following leads: 0 --- 230V --- 240V When it can be useful? I mean I can't think of situation ...
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2answers
105 views

How does this circuit give DC output? [on hold]

I didn't understand the working procedure of this circuit. It might be wrong. I ain't sure about this circuit correctness. Please anyone help me..
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1answer
36 views

Transformer voltage rating vs open-circuit voltage: what's the typical load assumed for the voltage rating?

This appears to have been asked in some way before (at Transformer: loaded vs open-circuited vs short-circuited) but both the question and the answers there are rather vague to me, so I'll try to be ...
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0answers
25 views

Protecting opamps from back-EMF, necessary or common in 70/100V audio?

Clayton and Winder's opamp book 5th ed. p. 283 briefly discusses the use of Zener diodes to clamp (as a TVS) voltage spikes from inductive loads from taking the opamp's output stage above its power ...
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1answer
41 views

Open circuit and short circuit test [on hold]

Why open circuit test is generally made on low-voltage side and close circuit test is generally made on high-voltage side? What if we did the test on the opposite side of the usual side?
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1answer
25 views

Rated load of a transformer

When the transformer is operating in rated apparent power, the voltage and current at the secondary side(is it the secondary side, please verify) is the rated voltage and current. My question is what ...
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3answers
58 views

Basic working principle of transformer

In a transformer power is conserved and p=vi. So, in a step up transformer, if secondary voltage is increased the secondary current has to decrease. Now, my question is, if the secondary winding in ...
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0answers
36 views

Three phase transformer question ?

we both agreed on the value of series impedance which is (12.82[82] ) however what i think he did wrong is the value of secondary reflected on primary since it is Y-delta 7967/480 = root(3) a ...
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47 views

How to make a transformer? [closed]

I want to make a 12 Volt DC transformer for a UPS. Can anyone tell me how to make this. and formula of winding and how to determine baben size and wire thickness and core size for 500W 700W and ...
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2answers
49 views

US to Australia [closed]

I know nothing about electronics... I need help to figure out if I can use a power adapter that I have on hand for my overseas trip. I have a Model PA-130 transformer for my Yamaha mixer. It's rated ...
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2answers
55 views

What purpose do transformers have in electrical interfaces such as ethernet? [duplicate]

Some electrical interfaces, such as ethernet, specify that the outward-facing socket are to be isolated by a transformer. For instance, see this circuit example from the data sheet of an ethernet ...
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2answers
75 views

Transformer core maximum power

so i am an EE undergrad, and i am wondering if and how exactly does a transformer core limit its power capacity. From my understanding, the rated power of a transformer is due to the current carrying ...
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0answers
51 views

60Hz to 50Hz frequency transformer/inverter?

I need to transform the frequency from 60Hz (220V) to 50Hz (220 or 230V). Alternatively I can use 110V 60Hz for the required output. I'm looking to find cost and space effective solution, it is for ...
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2answers
59 views

Shorting transformer leads

Sorry for a trivial question. I have a transformer with a tapped secondary coil: 12(blue wire)-0(black wire)-12V(2nd blue wire). I need to use it as a 12V supply source, so can use 0-12VAC (either ...
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1answer
70 views

Coil Winding Sense of Inductor/Transformers and Output Polarity

Given a solenoidal coil, if it is wound in one sense (say clockwise), would the output from it, in terms of polarity, be equivalent to another coil, wound in the opposite sense (counter-clockwise), ...
5
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3answers
240 views

When do I twist the wires going to transformer winding terminals, and why do I do it?

I sometimes see the wires of winding are twisted outside of the transformer (or inductor), as seen in the images below. What is the purpose of this? When should I twist winding wires and when ...
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6answers
866 views

Can the wire of a high voltage power line be used as the primary coil of an air cored transformer? [duplicate]

Back in the 90's I heard this story of a guy who in the 70-80's lived remotely near the power lines and that he was very good in electrical engineering and that he had free electricity by using the ...
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0answers
69 views

How to cascade transformers?

I'm currently working on a project were I need to cascade several transformers (the core we use does not nearly work as good as it ought to..). I'm using the equivalent circuit shown in (A), ...
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1answer
44 views

Modeling Capacitive Discharge Ignition (CDI) Circuit

I am trying to model a capacitive discharge circuit (see Fig. 1 below), but I'm having difficulty properly coupling the two inductors on the transformer and also estimating the energy dissipated ...
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2answers
109 views

Dual power supply without center tapped transformer

I am building a simple bi-polar power supply, that will be capable of -/+12VDC at around 1.25A. I have a mains transformer that brings 230VAC down to ~20VAC, with single windings on both sides. And I ...
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1answer
67 views

Can I make a step up transformer using these components?

I have a step down transformer that converts from 220 volt to 15 volt. I want to connect the secondary coil of this transformer to the output of 555 IC that produces ( 5 volt / 100 KHz ). Is there ...
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0answers
27 views

Magnetizing Inductance Vs. Mutual Inductance

1.) In the transformer equivalent circuit model, is the Magnetizing Reactance/Inductance the same as the transformers Mutual Reactance/Inductance? 2.) Does the secondary have a magnetizing reactance? ...
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51 views

How to read part number on a transformer? Inside Dell power adapter LA65NS0-00

I have a dell power supply that doesn't work anymore and am trying to salvage the parts: http://www.amazon.com/LA65NS0-00-Dell-Inspiron-notebook-Adapter/dp/B00115AOTA There's a transformer in here, ...
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2answers
89 views

How do I design a current transformer?

I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
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4answers
143 views

High Power Supply over a distance

I'm working on a project and have been stopped in my tracks part way through. I am designing a system that will power an RC over a distance. So I have a generator, and around 300 meters of cable to a ...
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1answer
32 views

Inductance in Transformers inductors

How can I find a transformers inductors value by using the derivative formula? If I want to generate high voltage spikes from a square wave generator of 10V p-p with a source resistance of 50Ω. I want ...
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2answers
62 views

Transformer inrush protection

New guy wound up here after running out of talent! Having tackled my first project using a mains transformer (in the UK - 230V), I haven't put any inrush protection into the circuit. The circuit is ...
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5answers
124 views

How can the infinite reactance of either primary or secondary in an ideal transformer draw current?

Assumption 1: An "ideal" transformer is said to have very large primary, secondary, and mutual reactance.. (self-inductance/mutual-inductance tending toward infinity), has a unity coupling coefficient ...
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1answer
52 views

Operation of a Growler to test armature shorts

Can someone explain to me how a Growler for testing electric motor armatures works please? I have obviously read the Wikipedia Growler page but it is still foggy. So the growler unit acts as the ...
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0answers
47 views

Safety / protection considerations for non-switching power supply

My quest for understanding the nuances of circuit protection continues. Today, I'm thinking about the power supply for a device I'm working on. It will need voltages which are somewhat hard to get in ...
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0answers
47 views

Why does ignition coil have polarity markings?

I know about one reasonable answer to this. The electron emission is easier from a hotter surface, which in a spark plug happens to be the central electrode. So we should connect this electrode to be ...
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3answers
123 views

How do I know if a transformer will output A.C. Or DC?

I recently bought a small transformer to transform 230V AC mains to 7.2V DC to power a small IC and relay. I wired it all up, but as far as I can tell, the output is AC rather than the DC I expected. ...
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1answer
72 views

Three phase transformer windings

I have a quick question about three phase transformer windings. if I have a transformer that is Yd11 but I connect the generator to the d-side instead(primary side). Does it become Dy11 connected or ...
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2answers
110 views

7809 Linear Voltage Regulator Outputs in Series

I'm building a linear power supply that converts 120VAC mains voltage into multiple 9VDC, isolated outputs. I'm using this transformer that has the proper primary winding and 8 secondaries that I'll ...
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0answers
51 views

Driving multiple IGBTs with gate drive transformer

I am playing with a circuit I've been working on, which consists of a stack of 15 IGBTs connected in series. The end goal was to drive this "device" with a single toroid transformer, where the drive ...
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0answers
31 views

Which configuration of transformer must be used to detect two phases from three phase supply of 440 volts

I am having a transformer which when input with two of the phases of supply(440 volts) is providing around 14 volts. But the same transformer, when used with single phase supply of 230 volts,provides ...
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2answers
69 views

Info on transformers? Where to find?

I'm quite often taking things apart to salvage the parts and use them in my projects. Right now I'm taking apart an old PC-power supply for a switch-mode lab-supply project. The power-supply in ...
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2answers
86 views

Design help for my 1A variable power supply

In a 1A Variable Power Supply circuit given below is it possible to use a 2A transformer and 1A bridge diodes.
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1answer
84 views

Amplify a 12 MHz sine wave

I need to take a 12MHz AC sine wave, from around 3.3V - 10V @ 10uA, output 50V, @ 1A (or more). I have the signal generator for signal input, but I am not certain what I need for a circuit to step ...
5
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2answers
229 views

Transformer current peaks

So I am designing a power supply, got everything calculated, and decided to simulate it for a second to see if the smoothing caps keep the voltage above the regulator limit at max current draw. What I ...
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2answers
53 views

What's a probable VA rating for this?

I bought a variac at a garage sale a few months ago and I've played with it since then with a 40W incandescent desk light. Now I want to use it for the incandescent house lights in a small theater. ...
2
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1answer
78 views

Transformer calculations and physics

I have an electrical engineering academic background, but since graduation, I have worked exclusively in software and my EE skills are admittedly getting very rusty. Something I never fully understood ...
0
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1answer
78 views

Series and parallel transformers?

I have two different transformers. The output of the first one is 15 volts and 1500 mA. The output of the second one is 5 volts and 500 mA. If I connected them in series (to get 20 volts) what will ...
0
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1answer
71 views

Use of Audio Tranformers in Amplification

I came across this ckt to make a wireless ear phones using Infrared Signals from IR LEDs. I am unable to understand the use of Audio Transformer here to amplify the audio signal, instead OpAmps would ...
0
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2answers
47 views

Step up transformer for low frequency AC with DC offset

What is the best way to step-up a low frequency voltage with a DC offset? I have the following signal coming from a function generator: \begin{equation} V_f(t)=8 Sin(2\pi f t+\phi) + 4 ...
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83 views

Is it OK to place ground plane under transformer?

I have a large transformer (50kHz, ferrite E-core) on the PCB. I want to pass power rails under it on the bottom layer. Should I place a large ground plane on the top layer to shield these power rails ...
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2answers
127 views

Square Wave input into Transformer

Can a square wave generated using an astable NE555 be used as input of a transformer instead of AC? Say, I generate a square wave of 60Hz using NE555 and a 24V at 6A supply and feed it into a ...
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62 views

Importance of IEC 61558-2-6 for isolating transformers

I'm baffled by why exactly some isolating transformers from the same line (of products) fail to conform to IEC 61558-2-6 (but still conform to IEC 61558-2-1) and what is the practical relevance of ...