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Questions tagged [transformer]

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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I cannot figure out what kind of transformer this is [on hold]

So I was told this is from a welder but I would like to us it for fractial wood burning but I cannot figure out what kind of transformer it is and how to do it, all the videos use microwave ...
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1answer
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Experiment with transformer: meaning of some physical quantities

I'm doing some experiments with a transformer, measuring some physical quantities. First I did an experiment with the transformer in open-circuit. I determined the voltages and currents on both ...
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Rectifier for transformer [on hold]

I’m searching an appropriate half-wave rectifier so I can use a neon sign transformer as a power supply. I want to be able to charge a HV capacitor using this setup. If this is possible would I need ...
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49 views

How can I match phase voltage between a transformer primary and secondary?

I am trying to make a circuit to transform 240VAC, split-phase to a 0 to 5V waveform for an Arduino ADC so I can measure the mains voltage. I have read this question (How to measure line voltage (220V)...
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57 views

Why bolted short circuit current in Arc Flash calculations much lower

Given single phase 240/120 transformers with 75 kVA rating and 2% impedance computing using the infinite bus short cut method 75,000 / 240 / 0.02 = 15625 amp or the long cut (with derivation) ...
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64 views

How does this isolation transformer protect user from transients/mains?

I'm looking at a pretty simple overvoltage/transient protection circuit designed to protect users but I don't understand what the transformer is doing. The circuit is designed to protect the output ...
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28 views

transformer to work in sinePWM waveform

How to design a transformer working with PWM waveform with the following data: fundamental frequency:50Hz, PWM switching frequency 10kHz. The transformer secondary should also be a PWM output, just ...
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2answers
64 views

Clipping an AC line voltage

I've got a linear step-up transformer (120V AC input) which has an output that under load nominally supplies 230V AC @ 100mA. But with no load it floats to as high as 280 V. I need to switch the load ...
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Questions about voltage drop at the transformer secondary and primary due to loading

Below there is an impedance matching aimed step-down transformer circuit where the primary to secondary turn ratio N1/N2=10. To actualize such turn ratio and voltage ratio, I set the inductor ratio L1/...
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Anybody please explain to me what is the Electrical Symbol CS means? [closed]

Please Explain What does the symbol i have marked in red Circle,means.& what is its function in this circuit..
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42 views

Correctly Using the Chan model in LTSpice

I am trying to use the Chan model to better simulate a transformer in my design. When I am making an equivalent transformer circuit, where does the Chan inductor go? On the LTWiki it is implied ...
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1answer
210 views

Short circuit current of 3-phase open delta transformer

For a 3 phase open delta transformers: When you are computing the short circuit current between the 208v high leg (point B) and neutral. Do you only use one 75kVA or do you add the other transformer ...
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65 views

For an Ideal transformer where permeability of the iron is infinity, why is the excitation current 0 if the secondary winding is open circuit?

I have read this question Why is the Exciting Current zero in an ideal transformer?. However I don't quite understand where his initial equation for the excitation current came from. Can someone guide ...
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61 views

What are the differences of a ferrite core transformer and an iron core transformer at low frequencies?

I made the BH curve of a ferrite core transformer and an iron core transformer with a 2V and 20Hz sine wave in input and saw that the BH curve of the iron core transformer is a bit larger than the ...
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1answer
58 views

Can I wire a transformer's dual primaries in parallel to double the output?

I have a dual primary (0-120V,0-120V) transformer with dual secondaries (0-6,0-6). For a quick test of an amplifier board, I need a 12-0-12 supply. What would happen if I wired the 2 primaries in ...
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1answer
66 views

Limiting current of a transformer used for resistance soldering

I'm working on a device capable of soldering wires to tiny components (3mm brass rings). I've used a PSU of a computer to make a resistance soldering device. Using the 5V line and a graphite stick of ...
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26 views

Flyback, primary inductance selection for wide output current changes

I would build my first flyback converter. Converter would be designed for 2A max and load device would draw about 100-200mA for most of the time with 1.8A peaks. Peaks would take a little longer so I ...
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2answers
58 views

Coupled inductor/pulse transformer for very tiny power supply

I need an isolated 24V 3mA supply to activate some optocoupler that will be read by some microcontroller. Its power supply will be the microcontroller's 5V. My first instinct was to use a flyback ...
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339 views

Is that a center tap tranformer just labelled differently?

my transformer has a secondary winding of 0 - 12v - 24v Is it just labelled differently and is it really a center tap where 12v would be the center, 0 would be -12v and 24 would be 12v? Thanks!
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62 views

Power Transformer question to power a motor load

So I bought a toroidal power transformer that can output 117Vac, 12.8A and has a power rating of 1.5kVA in order to power a motor that requires 115Vac, 13A. I wanted to see if this would be viable to ...
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2answers
56 views

How does this simple FM slope detector work?

I understand what happens from the diode onwards, it's a rectifying amp and a low pass filter that filters any unwanted frequencies from the carrier, but what is going on in terms of voltage between ...
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1answer
32 views

SMPS Transformer - Different Current Densities for Primary and Secondary

I've seen a design sheet of an isolated off-line 5V/2A flyback converter. In the "Calculating Wire Sizes" step the designer uses 4A/mm2 for primary and 10A/mm2 for secondary. This seems quite ...
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92 views

Power Supply Transformer with 3rd Wire on Primary

I'm sitting here with a $600 espresso machine with its power transformer not working (no voltage coming out of secondary, with 110V feeding the primary). I've been scouring the internet for a ...
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1answer
70 views

Replacing two 16.5V transformers with one

I'm an enthusiast so please be gentle! I have a transformer question and can't find a similar previously asked question. I have an ADT/Honeywell security/smoke system. We experienced a utility ...
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1answer
35 views

Tapping into a 5.1V transformer for a zero-crossing detection circuit

I want to make myself a reflow oven following more or less this guide: http://andybrown.me.uk/2015/07/12/awreflow2/ Here is the zero-crossing detection circuit diagram: Thing is I would like to cut ...
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Negative Turns Ratio on Transformer

What does negative turns ratio in the transformer mean? Some simulation software offers negative turns ratio, but in reality it does not exist. So what does it mean?
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So I bought a 3.2VA 15V transformer instead. This should do a better job for the voltage regulator? – [duplicate]

Voltage regulator not outputing desired voltage and extremely hot This means that there will be only something like 700mW of power so no heatsink is needed.
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1answer
83 views

Core rope rom not working

I am trying to make my own core rope rom, according to the link. I have 15mm ferrite cores, which I wound about 30 times with 1mm magnet wire. I thread the primary ( also 1mm wire) through one of ...
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1answer
63 views

Transformer mains identification

A friend gave me a transformer from an APC UPS that supposedly was capable of \$1300 VA\$ (I have my doubts, but it is very large and I am not going to be using nearly so much power, so OK). He doesn'...
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91 views

Voltage regulator not outputing desired voltage and extremely hot [duplicate]

Now that I have understood how to connect my transformer to output 18V, I now have a huge problem with heat and wrong output voltage. I also smells and you can feel the heat. Here is my design ...
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1answer
75 views

I am trying to understand this reading

So I bought a transformer VC 18/1/16 and when I plugged 240V to from the mains to the primary winding. I then plugged into my voltmeter and it is suppose to show 18V . Does this seem correct on my ...
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3answers
66 views

Inductance value of an Isolation Transformer

There is a small isolation transformer 'L1' of 1:1 ratio as shown in the image. A 0-24V, 75kHz square wave is applied from push-pull mosfets stage at the 'V_SW' input of the circuit. I want to find ...
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1answer
47 views

Connecting transformer with single input and secondary two outputs

So I bought a transformer VC16/1/18 and it has two outputs. I want to get the full output on a single output. Does this look correct? The updated one Corrected not Final
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80 views

Computing short circuit current of transformer

Update: My 500Va is just an example. What I wanted to compute was the short circuit current of utility pole transformers because I want to estimate how large an arc flash that can be produced. ...
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Connecting the secondary side of ignition coil to earth

I have an ignition system used for some application. During the testing I found that spark plug is producing EMI due to spark occurrence and high voltage is traveling through the wire. So to ...
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Transformers and high voltage elements

I've been trying to learn how to properly set up a circuit for power regulation. Often I hear for domestic use that it is better to use a transformer to isolate the device as well as stepping down the ...
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2answers
63 views

Must the air gap in a transformer always be perpendicular to the magnetic field lines?

The air gap in a transformer seems to always be spaced across the cross section of the core, where the magnetic field in the core has to then flow across it. Since the core is typically made of ...
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Replace 24VAC 20VA transformer with standard power supply

I have the following transformer (source): Sticker reads: Pri: 120VAC 60Hz 30W Sec: 24VAC 20VA I want to replace it with a standard, power supply without screw ...
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Beginner's second PCB circuit design: AC to DC

I am designing an AC to DC converter and I just want to make sure that I am so far doing the right thing — placement of components and wiring etc. — as I am a beginner. Does this look ...
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1answer
35 views

Transformer fuse for primary coil. 240V with 16VA

So I know it may be a basic question but hear me out. These are the specs for the transformer I would like to buy. To add a fuse to the primary coil I would do 16VA/240V which gives 0.06A. Does that ...
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2answers
77 views

Tape recorder with live chassis [closed]

I am trying to repair a Revox B77. The issue is that the whole machine is live. I am looking to know if the issue is with the voltage selector or even some guidance as a starting place where to look ...
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1answer
44 views

Transformer powering an alarm system heating up

I have an alarm board from Paradox, model SP6000. I power it with 16Vac/2.2A from a 40VA transformer which is connected to the electrical circuit from my house(230V 50Hz). The board has an AUX power ...
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40 views

How to calculate fuse size for primary coil?

How do you calculate fuse size for primary coil? I have an 230V AC to 18V DC. What are the steps please?
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1answer
29 views

Digital voltage stabilizer relay diagram

I am using this voltage stabilizer relay diagram below, which provides a 16 step-up level. I need to edit it, so that I can made it to work as step-down in case of high voltages such as 245 and above. ...
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1answer
54 views

Home voltage stabilizer circuit

I am designing a 12000W voltage stabilizer transformer. I saw in another design that they use on the AC neutral a 10W resistor linking on the branch on relay contacts so that the neutral is taken from ...
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3answers
54 views

secondary voltage of practical transformer question

I am working on a practical transformer question as seen below. My thought process to solve this question was: 1) Calculate the total current supplied by dividing the apparent power by the voltage. ...
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1answer
42 views

What does it mean for the connections of this transformer to be in parallel?

Using this transformer, datasheet. When the datasheet indicates that the windings are connected in parallel, is it referring to connecting pin 1 with 2, 11 with 12, 8 with 7, and 6 with 5? If yes, ...
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2answers
39 views

measuring resistance on hv transformer

I need to verify the resistance on a HV transformer that receives 208v single phase through terminal 1 and 2, or 240v through terminal 1 and 3 and delivers 4000v through terminal 4. As per the ...
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1answer
49 views

Mains transformer as line matching audio transformer

If we were to use a small mains transformer in place of a line matching transformer to drive a speaker, would it work at all? Are there differences in laminations or core materials that set them ...
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2answers
104 views

Power output of ignition coil - 2.0 [duplicate]

There was an older question about "Power output of ignition coil". The system would not let me comment on that question. So, I'll ask here. In regards to a ignition coil (non specific). OK,you have ...