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.

learn more… | top users | synonyms

3
votes
2answers
78 views

Using a transformer with 400 volt rated primary side with a 120 volt line

Is it possible to use a transformer rated for 360 to 400 volts on its primary side on a 120 volt line? Will it still perform adequately? And I would assume the turns ratios still apply? This is the ...
1
vote
3answers
175 views

Linear Power Supply Advice

I am new here to StackExchange and new to electronics in general. As my second electronics project (the first being a blinker circuit for a bandolier of LEDs) I am building a regulated linear power ...
0
votes
1answer
25 views

Using distribution transformers vs direct connection to primary switch gear

I am trying to learn more about transformers and low voltage electrical distribution. Say you have a medium sized industrial building with a primary switchboard feeding several load centers ...
1
vote
3answers
71 views

Transformer size vs. frequency

The size of 60Hz transformers are larger than 50Hz transformers. Transformers designed for operation in the kHz range are even smaller. Why does transformer size decrease with frequency?
0
votes
1answer
37 views

How would I properly develop a current rating for this system…?

I have a system that I have recently developed for in house (manufacturing) equipment testing. Transformers rated for 80VA (264V, .303A) are used in series and rectified using a full-wave diode ...
2
votes
1answer
52 views

Transformer frequency dependence

I have a transformer that I've taken out of scrap. I'm trying to discern it's electrical specifications. In my setup I have a function generator hooked up to the primary winding, and an oscilloscope ...
0
votes
0answers
23 views

LV halogen transformer for dimming via PWM control

I am looking for some advice regarding my plans to assemble a circuit to dim a halogen bulb. I am planning to use the principle of switched mode power to control a halogen bulb. I intend to ...
0
votes
2answers
47 views

Transformer Rating Selection

For selecting a transformer, I stumbled across the following equations for obtaining VA and IAC (citation here). I am dealing with a full wave bridge rectifier with a capacitive load. The wiki ...
1
vote
1answer
28 views

Voltage stepping and current reduction

I'm designing a drone to use a relatively new form of propulsion, electrostatic fluid propulsion, which requires extremely large voltages (in the order of 10-100kV) running through a wire to ionize ...
0
votes
0answers
13 views

How can i model and simulate transformers in PSCAD?

I am trying to model distribution transformer in PSCAD(Power System Computer Aided Design). I have used the direct block that is in PSCAD, but it has limited input parameter. The input parameters are ...
0
votes
0answers
27 views

Temperature as a factor in the design of a transformer

How to simulate climate and environmental conditions which is required for the design of a transformer? I am trying to optimize size of winding conductor and size of core used in a transformer. To ...
0
votes
0answers
22 views

Transformer Efficiency for Galvanic isolation?

I am using a transformer to create a galvanic isolation between the input and the output side. The circuit is low power circuit, so over all, it can not consume more than 3mA. I am driving the ...
0
votes
0answers
64 views

provide 3.7v source to android tablet

Android tablet mostly needed a 3.7V Lion battery to run on it. If I were to replace the battery with a power source, how can I provide such a 3.7V source from some existing products such as 220V/5V or ...
1
vote
1answer
38 views

Using an electrical transformer for simple project

I have an electrical transformer with 4 wires.. an orange pair and a black pair.. I have measured the resistance across the black pair, and it is significantly higher than the resistance in the orange ...
0
votes
0answers
32 views
2
votes
1answer
69 views

Does a 300W Transformer use 300W when a 12W appliance is connected?

I've been wondering: if you connect a 12W device to a 300W step-up transformer, how much power is consumed? Does it use the whole 300W the entire time, regardless of what's connected, or is it an ...
-1
votes
0answers
48 views

Connect single phase loads to three phase supply

I may need to opt for a three phase supply if the single phase loads need more than 3.6kW. In that case I'm looking for a way to use those loads with that supply. In a previous thread (which was ...
1
vote
1answer
182 views

What is the purpose of the capacitor in this transformer circuit?

I a audio DAC output stage I have seen the following circuit. It's function is to convert an balanced signal to an unbalanced signal. IN+ and IN- are differential outputs that are biased at 2.5V. ...
0
votes
0answers
43 views

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 ...
0
votes
4answers
91 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. ...
1
vote
4answers
157 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 ...
0
votes
2answers
168 views

How does this circuit give DC output?

I don't understand how this circuit works. I'm not sure if it's correct. It should give a DC output, but how would it do that?
0
votes
1answer
41 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 ...
1
vote
0answers
29 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 ...
0
votes
1answer
28 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 ...
1
vote
3answers
75 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 ...
1
vote
0answers
48 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 ...
0
votes
2answers
50 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 ...
1
vote
2answers
65 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 ...
0
votes
2answers
84 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 ...
0
votes
1answer
101 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 ...
0
votes
2answers
64 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 ...
0
votes
1answer
104 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), ...
4
votes
3answers
252 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 ...
8
votes
6answers
941 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 ...
2
votes
1answer
261 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), ...
0
votes
1answer
64 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 ...
1
vote
2answers
172 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 ...
0
votes
1answer
74 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 ...
0
votes
0answers
32 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? ...
0
votes
0answers
58 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, ...
3
votes
2answers
104 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, ...
5
votes
4answers
150 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 ...
0
votes
1answer
39 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 ...
0
votes
2answers
72 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 ...
0
votes
5answers
166 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 ...
1
vote
1answer
70 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 ...
0
votes
0answers
50 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 ...
1
vote
0answers
53 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 ...
0
votes
3answers
135 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. ...