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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76 views

Circuit Representation of an Unknown Switching Transformer (Including Dot Notation)

Is there a way to identify the phase of the transformer's coils without having to see its waveform in an oscilloscope? For example, I have this unknown switching transformer The only thing I know is ...
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What are the qualities of this coil?

This coil was donated to me. If someone could define it's specifications I would be most grateful. Also feel free to input suggestions for alternative uses.
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Why should the primary winding of the transformer not be grounded?

I've been wondering what would happen if you grounded both star points of a Y/Y connected transformer. This shouldn't affect the voltages, so why really is it not advised to earth both the primary ...
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143 views

Building a HV transformer

I built this circuit recently though it did not work for me https://www.instructables.com/id/Variable-voltage-ignition-coil-power-supply/ Using this coil https://www.autosurplus.com.au/brand/...
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43 views

The things affecting operation of a transformer

While using transformers, is it only the winding ratio that matters? I cannot understand one point that the voltage between primary cables of a transformer is very low when I measure. It is logical ...
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Best way to generate 26 Volts AC at 380-420Hz?

I have obtained a military vibrating-reed frequency meter that I would like to turn into an educational display unit, with a knob that adjusts the frequency from 380 to 420 Hertz, giving the user the ...
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Can a cheap transformer be used for twice the rated voltage?

Can a step up transformer designed to step up from 110v to 220v be used to step up from 230v to 460v? (I'm thinking one of those cheap Chinese auto transformers from ebay, in the 1kva-2kva range) I ...
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228 views

Energy in transformer air gap

Here is the following assertion : Question: Why is it commonly stated that in a flyback transformer, the "air gap carries most of the stored magnetic energy"? Answer: We can intuitively ...
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1answer
76 views

How to implement a transformer into a boost converter instead of an inductor

I am trying to build a boost converter that would output a high DC voltage (several hundreds). My concern is that I should use a transformer, but how should I implement it so that DC voltage input is ...
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How is voltage induced in Yd transformer without neutral connection sinusoidal?

Thia is regarding bank of 3 single-phase transformers having star connected primary with isolated neutral and delta connected secondary. I know that for bank of 3 single phase transformer core flux ...
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2answers
66 views

Transformer broken?

I have a transformer that is labelled: Class 2 Transformer AC/DC Adaptor Model: OH-57090DT Input: 120VAC 60Hz Output: 9VDC 2500mA The transformer came with a ...
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how is this transformer working with DC? [duplicate]

As I was going through the SMPS circuits online I came across this circuit: I searched and learned that the transformer steps down or step up only AC power supplies and then converted to DC using ...
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5 V home network

I'm planning on adding multiple IoT devices in my house, and I'm looking for an elegant solution to power them all. They'll all need 5 V, a small number of them (cameras) would draw up to 2 ...
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1answer
66 views

How should I drain a capacitor in a rectifier circuit?

I am trying to learn how to drain a capacitor after disconnecting power from a rectifier circuit. Specifically what I have is a step down transformer from an old wall wart charger that I have modified....
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153 views

Does a Center-Tapped RF Balun Perform Better than Untapped Baluns?

To my knowledge, a conventional transformer is a balun - you simply connect a single-ended signal at the primary side, you get the balanced signal at the secondary side - magnetic coupling doesn't ...
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How to interpret the FFT of the mains voltage in this case?

I coupled the 230Vrms AC mains voltage to a scope channel through a 10Vpk-pk step-down transformer. I can imagine the transformer will already filter high freq. noise but I thought I can still see ...
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60 views

Transform low AC voltage input

I have 2.2 volts low impedance AC from a constant source. If I build a transformer to input 2.2v on the primary and output 120v on the secondary can I expect to operate any household appliances, such ...
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81 views

Induced EMF in electrical machines

I am currently working with machines and when I try to understand their principles in-depth, specifically in machines, I got to know that EMF is induced because of any of the two reasons: 1) Time-...
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1answer
122 views

Overhead transmission line voltage

Consider an overhead transmission line (not cable) and from whatever reason, one phase is out. Now, if secondary side of transformer at the beginning of transmission line is grounded star, there will ...
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Difference between magnetizing inductance and primary inductance

What is difference between magnetising inductance(Lm) and primary inductance(Lp) of transformer?
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54 views

SVC-350 Power Supply Modification

I am trying to modify a Roland SVC-350 that is currently configured for 240V power to run on 120V. I ran into some questions as I was speccing out the transformer that I needed. The full schematic ...
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1answer
98 views

How to terminate unused transformer pins?

What is the correct way to terminate/wire these unused transformer pins? Do they get tied to GND?
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126 views

Understanding Electric Shock Box Circuit

I have just bought an Electric Shock Box Kit. I am trying to understand how the circuit works, so by doing reverse engineering I obtain the next circuit: I don't understand how is generated the ...
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Parallel transformer output not expected RMS value

I have a 115V/230V transformer with specifications of: outputs 10V (parallel)/20V (series) and 1.2A (parallel)/600mA (series). Product I'm no electrical engineer, but I need to get this set up to ...
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89 views

Fast-blow instead of slow-blow fuse in consumer hifi power supply

I have a power supply unit for a hifi pre-amp. The power supply takes a slow-blow fuse (T2.5A/250V). If I use a fast fuse (F2.5A/250V) instead, how likely is the fuse to blow during normal power-on?
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Reducing power draw from appliance

I have an appliance (electric skillet) that draws 1500W when plugged into a regular (120V) household circuit. If I want to be able to use it on an inverter that can supply max 1000W@120V, can I build ...
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How does this circuit start up?

I'm trying to understand how CI HT7A6322 starts up. Relevant part of the datasheet says: Control circuit power supply. Also provides a charging current during start up due to a high voltage ...
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1answer
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How to calculate primary, secondary, and auxiliary inductance of this transfromer?

I am wondering how to calculate/find out the inductance values for primary, secondary, and auxiliary windings of a Würth Electronik 750310742 transformer. The main reason is so that I can attempt to ...
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147 views

Transformer construction diagram

Contoller datasheet Can anyone explain how the actual winding happens?. The transformer is a shell type transformer used in a flyback circuit. The circuit is not working, and I'm suspecting the ...
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193 views

Why don't people power LED strips in parallel instead of using amplifiers?

The common pattern to run long LED strips seems to use separate transformers and amplifiers in between the individual strips. Why not use a single transformer, controller and appropriately thick ...
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1answer
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Relationship between voltage and current of a power transformer [closed]

I'm currently analyzing data from a power transformer and I stumble over the circumstance that voltage and current is almost not related to each other. Since I'm not an engineer I wonder why is this? ...
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Does input impedance of an isolation amplifier or a transformer have impact on common mode to differential mode conversion?

I have a question where I can only explain it clearly by an example. It is about conversion of common-mode interference to differential mode due to overall system imbalance. I will use below two ...
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Why are many 9V DC wall adapter power supply measured as 12-14V by a multimeter? [duplicate]

I have tried with many (working) 230V - 9V DC wall adapter power supply (of different brands, some of them coming with an electronic Yamaha device, etc.): they all show a higher voltage when ...
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Should you Megger test transformers?

I have heard people say you shouldn’t Megger test transformers because the high voltages used might cause insulation between windings and between windings and the core to breakdown. Is this true? ...
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Which capacitor in series with resistor circuit to reduce remanence effects of transformer?

The "Comparative Analysis of Mitigation Techniques for Inrush Current of Transformer" mentions "Pre-insertions resistor with capacitor method" as an inrush mitigation technique: When circuit ...
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Transformer very basic questions [duplicate]

Good day for all. My question is about the power on a transformer and its functionallity. I know that the power is the same in both inductors (ideally), if I've a source at 240V/10A then the power ...
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171 views

Why is there a resistor between the primary and the secondary winding?

I recently opened up a linear power supply and found out it has a resistor of 8.2M ohm between the primary winding (specifically in the neutral) and the secondary winding of the step-down transformer. ...
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102 views

Is this the correct way to wire my transformer?

I am building a 12 V dual power supply. Since this is the first time I will be using mains (230 V). I would like to make sure that I am not going to burn down my house. The transformer I want to use ...
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Which has less energy loss - AC step up/step down transformers or DC to DC step up/down converters?

In the EE field, AC transformers are constantly talked about. However, I don't hear much of DC to DC converter modules, even though DC is widely used today, mostly in smaller electronics. Both of ...
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100 views

DC voltage after rectifier

Is my calculation correct? I want to tranform 240Vac output of 5Vdc after voltage regulator. The transformer I am interested in is VB 2,0/1/6: https://docs-emea.rs-online.com/webdocs/0f46/...
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142 views

Supplying an MCU from 110 or 220V line [closed]

I've been struggling with this for a while : am looking for a way to power an ESP32 microcontroller (at 3.3V, or 2.6-3.6V) from a 220V line. I am trying to do this using only my home'e electrical ...
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Are the topology of these flyback transformer for PoE the same?

I am looking for a transformer with the topology like 750310059 as shown below unfortunately the winding ratio and L value will not work with the PoE controller (MP8007) I am using for my design since ...
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1answer
130 views

Center tap transformer pairing with ATX PSU

I'd like to use both a beefy center tap transformer (220v to 24-0-24, 1000VA) and an ATX PSU togheter, to power some lab equipment. So I isolated from case the ATX GND on DC side as the case is earth ...
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3answers
79 views

Safety and isolation transformers

What safety measures can be taken when using a 1:1 isolation transformer in order to avoid electric shock even if someone touches both ends of the secondary? Would an insulation monitoring device be ...
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Flyback Isolation Transformer Alternative

I am using the mEZS84801A as a reference design as shown below. It uses the MP8007 PoE chip. I have modified and tested this PoE system successfully and my camera be powered and it can run at 1 ...
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1answer
47 views

dimmer on input of stepdown transformer for amp regulation?

If have a step-down transformer designed for low voltage high amps, and I put a dimmer on the input will that allow me to lower the output amps? I don't care about voltage as it will be negligible, I'...
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28 views

Isolation voltage of a flyback transformer

How to calculate the isolation voltage of a planar flyback transformer? Or if there are any standards about it? I am designing a planar flyback transformer that need an isolation voltage of 1000V, ...
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163 views

Self-oscillating converter circuit

I need some help with understanding following DC-DC converter circuit: (Just for clarification, the three windings are on the same transformer core) simulate this circuit – Schematic created ...
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71 views

Two questions about astable multivibrators and transformers

Here's something that confuses me: The output on an astable multivibrator will be shown on a multimeter as half the input voltage (for example we have 9V-0V-9V-0V...and the multimeter averages it out ...
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What would happen to the turn-on transient if I add a capacitor in parallel to a transformer?

I have a welder with a big air gapped transformer. Input specs: 220V, 3200 W active, 25 A total (cos Phi 0.56). Output specs: at full load 110 A welding current. I haven't checked whether output is DC ...

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