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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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Voltage wrong reading for ph_ph

I measured ph-ph voltage (l1-l2) equals 100 v, (l1-l3) & (l2-l3) equals 55 v. However, when I measured ph_n equals 55 v for the 3 phases. I tried to measure earthing but all neutral points all ...
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42 views

Voltage drop pulse transformer

I'm trying to design a buck converter controlled by a PWM signal. The PWM signal and the converter is isolated with a pulse transformer. My issue is that the pulse transformer behaves differently ...
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33 views

Short circuit calculation for KNAF transformer

I am using a 2MVA transformer (KNAF rating will be 30% more at 2.6MVA) The question i have is whether we calculate the short circuit rating based on 2MVA or 2.6MVA? I'm using pu method to calculate,...
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46 views

What is Vrect in a Voltage Regulator?

I'm just reading through Texas Instruments' Application Report on Switching Regulator Fundamentals and came across the half-bridge converter and the formula for both the output voltage of the entire ...
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46 views

About transformers: very little primary current if the secondary is unloaded

This extract is from a popular electronics book: ... a transformer of turns ratio \$n\$ increases the impedance by \$n^2\$. There is very little primary current if the secondary is unloaded. I'm ...
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31 views

SMPS Transformer affect RFID card

In my circuit, RFID card sometimes works sometimes not. it depends on how I put the card on RFID receiver. Usually it does not work when I put around the smps transformer. I guess SMPS transformer ...
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24 views

furnace transformer

We have a 120 MVA furnace transformer. While charging it in no load and with out electrodes the phase to ground voltage showing almost same as phase to phase voltage. Vector group is Dd0. The phase to ...
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67 views

Current limiting ballast for a transformer

So, guys, I hope you can explain to me how to calculate the necessary parameters for a ballast to limit the current on the primary side of a high voltage transformer.It is for a tesla coil project. To ...
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65 views

Dell power adapter does not get warm? [closed]

Usually I notice that power adapters get warm whether they are being used to power a device or not. The rectangular Dell computer power adapters, however, do not seem to get warm unless they are ...
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Sizing a transformer circuit breaker UK

I am trying to size a circuit breaker for a transformer. The transformer is three phase 480 : 4160 V rated at 25 kVA. From my calculations there will be approximately 30 A on the primary and 3.5 A ...
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1answer
22 views

Finding Transformer Leakage Impedance from S/C, O/C and Winding resistance tests

I've recently done an experiment on a 415/100 V transformer. Performing the S/C test on the HV side and the Open Circuit test on the LV side and finding winding resistance from applied DC voltage and ...
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4answers
60 views

The fields and waves associated with a transformer

Induction in a transformer happens via a fluctuating magnetic field in coil A inducing a voltage and hence current in coil B. An electric field is associated with a fluctuating magnetic field. Is ...
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Open and short circuit voltage in magneto primary coil

As illustrated in figure 1 and 2, I measured the voltage across the primary coil of an aircraft high-tension magneto in an open circuit condition (figure 1) and short circuit condition (figure 2). The ...
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58 views

What does this transformer symbol mean

In a balun I have, (model 50-7725 from CPC, datasheet -> http://www.farnell.com/datasheets/2365902.pdf?_ga=2.142463986.1590159842.1535980880-667311346.1535980880) It shows the Balun as: What is the ...
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41 views

What will happen when taps at secondary side of auto-transformer are connected together (short-circuited)?

In case of Auto-transformer, there is only one winding, having three lead wires (1 for primary/input, 1 for secondary/output, and 1 common between both). At the secondary side (the output side), there ...
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Can a short circuit in the output of a transformer be dangerous?

Assume that I have a 220 to 12 volts transformer with a nominal output current of 3 A (marked "12 V 3 A"). Now what does happen if I connect the two output wires to each other or to a load with very ...
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765 views

If I convert 10 V, 1 ampere to 5 V, do I get 5 V 2 ampere?

I know the current in the circuit is the same. And also, Power = 10* 1 = 10 watts. So, 10 = 5 V * (x) ampere, X = 10/5, X = 2 ampere, With some loss while using a voltage regulator, I will ...
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55 views

Simple power supply circuit loses voltage over time

I have a simple circuit that I built from a 120V to 18V transformer, a bridge rectifier and a few passives. I have a voltage divider because my little $20 oscilloscope can only handle max 12V. I ...
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51 views

Regarding Power Market demand and supply

As I have read, that power supply should be equal to demand. As it can't be stored .So basically this means power is generated in real time. Consider an area where power comes from a Substation A, ...
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64 views

How to convert 2 phase power supply to 3 phase power supply using a Transformer (like Scott transformer)?

I'm looking to develop a circuit to convert 2 phase power supply to 3 phase power supply. My circuit follows: Input: 2 phase 400V - phase angle 120degree Expected output: 3 phase with phase to ...
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1answer
40 views

Voltage induced in aircraft high-tension magneto ignition system

Why is there no voltage induced into the secondary winding (in high-voltage step-up transformer) when the ignition switch is closed (OFF)? When the current flows in the primary winding of the coil a ...
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33 views

I have designed an emergency light circuit, but I am unable to design a battery overcharge protection for it. Can any body help me with it?

Here, I am giving the circuit diagram for the same. For battery: I am using 4 Ni-MH battery, each of 1.2 volt and 2100mAh in series. I haven't tried any approach for battery overcharging protection, ...
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1answer
79 views

Trouble Powering Microcontroller from Doorbell Transformer

I am working on a project that involves an IoT device, with a 3.3V microcontroller, powered from a doorbell transformer. In an earlier question, I was attempting to solve an issue with a bridge ...
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3answers
118 views

Process for Making a Flyback Transformer

I am looking to make my own flyback transformer that can put out a DC voltage from 0 to -40 kV DC and a power of 400 watts, as most commercial flybacks do not go up to the specified power and ...
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58 views

Turns ratio of multi winding transformer

Hi can anyone let me know what is the overall turns ratio of the transformer shown in image below as i was confused
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70 views

In an ideal transformer circuit, how is power transferred?

If I have a system of circuits like this: where Circuit 2 is providing power the Circuit 1, where does the energy come from? Do the inductors store energy? If not, how is power transferred from the ...
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1answer
92 views

Audio Transformer output straight into an opamp?

Below is a circuit I'm working on. It's a guitar input buffer featuring transformer isolation. The transformer I'm using is pretty expensive and should be fairly linear, but I decided to add a graphic ...
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1answer
111 views

why do the electronic transformers that i remove from circuit boards keep exploding when connected to a 230v main [closed]

for the past 3 months I have removed several transformers from PCBs to try and use it for a different purpose ,but as I connect it to a 230v main supply they just keep exploding . I don't think my ...
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10answers
2k views

Best approach to step down 220VAC to 160VAC?

Hey Electrical Engineers, I'm a newbie to electrical engineering (I am a software developer by trade and am starting to work with Raspberry Pis and want to learn about basic circuit design). My ...
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2answers
86 views

What does this RC network do in this audio transformer output stage?

This is a relatively well known ABY circuit available on the internet. CLICK HERE, REMOVED IMAGE FOR COPYRIGHT REASONS I have two questions about this circuit : 1) What does the RC network (in the ...
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1answer
21 views

Question about equation for LT3750 capacitor charger IC

I have a question about the equation for minimum primary inductance on page 8 of the data sheet for the LT3750 high voltage capacitor charging IC. The equation in question: $$L_{\text{pri}} \geq \...
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1answer
47 views

Building a High Voltage Rectifier with a continuous negative output

simulate this circuit – Schematic created using CircuitLab In the past, I have worked with high voltage projects, but seldom with HV rectifiers. Thus, I was curious how I could build a ...
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Scaling of magnetic field strength and flux density measurements and shape of hysteresis loop

Note: this is part of a larger question which I was asked to separate into subquestions. Other subquestions: 1 and 2 I'm using the method outlined here to measure the induced magnetic flux density in ...
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Cutoff frequency of passive RC integrator used to measure magnetic flux density

Note: this is part of a larger question which I was asked to separate into subquestions. Other subquestions: 1 and 2 I am using a passive RC integrator to measure the induced magnetic flux density in ...
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1answer
26 views

Buffering the input to a passive RC integrator used to measure magnetic flux density

Note: this is part of a larger question which I was asked to separate into subquestions. Other subquestions: 1 and 2 I'm using the method outlined here to measure the induced magnetic flux density in ...
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2answers
29 views

RS universal rectifier transformer secondary voltages

This looks like a good place for some advice on this strange multi tap multi coil transformer, this RS lump of a 40-0-40 @ 1A transformer came to me after an earlier eBay purchase was delivered ...
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Magnetic path length for partially wound toroidal transformer core

According to Wikipedia, magnetic path length is defined as "the effective length of a closed magnetic loop inside a magnetic core made of ferromagnetic material." Thus, for a toroidal core that is ...
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2answers
60 views

What is the principal of Inductive Conductivity sensor?

What is the principal of Inductive Conductivity sensor which uses two coupled coils to estimate conductivity? Image Source I understand that the eddy current losses changes with the conductivity, ...
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54 views

Safety of an Inverter Circuit

I built this circuit for an EL driver/inverter I found on this website: https://dcroy.blogspot.com/2011/02/ The transistor is a TIP122 Darlington transistor and I used this transformer in the circuit....
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1answer
59 views

Transformers headroom and “mandatory” components

I have calculated the maximum (Worst Case) current consumption of my circuit to be 88mA. Looking at transformers I found one at an specified max output current of 90mA for parallel winding which is my ...
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3answers
131 views

Can a transformer have no secondary stages?

While disassembling the power for the spindle of my hobby CNC mill, I came across something peculiar which I think warrants a question on this site. The input is standard 220V AC. Phase 1 (brown) ...
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2answers
60 views

how could a 3 amps transformer deliver 3 amps after filtering?

I saw this project of a linear power supply, and I couldn't understand how the output can deliver 4 amps assuming maximum current of the transformer of 4 amps before the voltage starts to drop. I ...
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1answer
32 views

Flyback from ignition transformer?

I'm using a 10kv ignition transformer for a jacob's ladder. It works great! Currently though I've only tested it on its own circuit. But I would like to have this thing running in my lab. (I know not ...
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1answer
47 views

Need Some Information on a Transformer [closed]

A few years ago I found an old Peavey Standard 260 and I just took it apart for parts. I want to try to use the transformer for something, but don't know anything about it.
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2answers
109 views

Can any meter be PT connected?

I have an EE background, but am new to metering hardware. Looking at metering equipment for high voltage measurements (up to 6.6 kV), it seems most only go up to 480 V, even when classified as ...
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2answers
51 views

Can a MOSFET generated high voltage (315v) pulse train be measured using a DMM in AC mode?

I am using a 5V pulse train generated from a UC3845 PWM controller to trigger a MOSFET (K2645) which is biased with 317VDC in series with Rd= 120ohms, Rs=20ohms and primary of the PWM transformer. I ...
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3answers
684 views

How does Galvanic isolation work?

I am unable to understand how does galvanic isolation work either via an optocoupler or a transformer. In an optocoupler, the input side current caused LED to emit infra red light which basically ...
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1answer
43 views

Current input and output of transformer

I'm trying to make a welder-like transformer, but I'm having the problem that apparently I'm drawing too much current from the primary side of the transformer as the variac I'm using to supply about ...
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6answers
114 views

why does a step up transformer cause lower currents?

The usual answer I hear is because power needs to be conserved, but I dont find that answer satisfying. Normally if I were to double a supply voltage in a circuit, then I would expect twice the ...
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1answer
31 views

90 degrees phase shifted magnetic fields

If we have a closed magnetic circuit with two primary coils and one secondary coil wound on it. The primary coils are wound such that unlike poles are adjacent. Both primary coils are using rectified ...