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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47 views

How four wires are replaced with two wires in early telephone?

In this video, when A wants to talk to B, a microphone was connected to a distant speaker using two wires(A --> B). When B talks to A, a copy of above was used in the other direction(B-->A) ...
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35 views

How to troubleshoot low-voltage home lighting system from 50s

My home, built in the 50s, has a Sierra low-voltage lighting system, where low-voltage 24DC switches control relays that power the normal 120AC lights. In the last week, the switches have failed ...
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76 views

No voltage induced in secondary coil of transformer with 5V 1.5 kHz voltage from Wien bridge oscillator in primary coil

I have built a Wien bridge oscillator which outputs 5V at 1.5 kHz. When I hook up this output to the primary coil of a transformer I can't measure any voltage in the secondary coil. Schematic: ...
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3answers
107 views

Is it possible to model a single-phase phase-shifting transformer in LTspice/Multisim/PSpice?

As you know, three-phase two-winding transformers can produce a phase-shift between the line-to-line or line-to-neutral phasor voltages of one side and the respective line-to-line or line-to-neutral ...
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1answer
195 views

High Voltage Planar Transformers

I am designing a high voltage DC/DC converter that is for an aerospace application and therefore I am focusing on reducing the size and weight, so switching at a high frequency possibly integrating ...
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1answer
49 views

Need help for Air core transformer design

I am trying to develop an 1.5 kW induction heater. The circuit is supposed to have a high frequency (72 kHz) air core transformer for providing electrical isolation and impedance matching. I am a ...
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32 views

Need some suggestion on 220 - 3.3 volt 500 mA power supply (Or 12 volts maximum)

I was planning to make some 220-3.3 volts,5 volts & 12 volts power supplies. I tried the configuration above in proteus (0.47uF, 275 volts RMS, Polypropylene film capacitor in series with a small ...
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1answer
3k views

3 phase transformers and equivalent circuits

There is an exercise in my textbook that goes like this: 3 single phase transformers are connected in wye-delta configuration. Each transformer has the following parameters : R1, X1, Rc = \$\infty\$, ...
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1answer
162 views

Can this example be used for explaining the effect of lamination on power loss in a power transformer?

I'm trying to demonstrate to a group of people how a lamination of the transformer core reduces the power loss due to Eddy currents by not using any complex math. I start with a non-laminated core as ...
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3answers
5k views

How to Model a Transformer in LTSpice

I am modeling a low voltage single phase electrical distribution system with a step-down transformer using LTSpice (source is 480Vrms step down to 120Vrms). In LTSpice instead of setting the turns ...
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3answers
809 views

Change in transformer efficiency (leading power factor) with increasing load current

Does efficiency increase or decrease when the load current increases (assuming copper losses equal iron losses along with a leading power factor load)?
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1answer
4k views

Transformer - If the Output V number matches, does it matter that the A numbers are different"

The transformer that came with my Kinkle Fire say "DC Output: 5V1.8A". I want to install some Fastmac Usockets in my house but their specs say "Output: 5VDC 2.4A". Do the different A numbers matter? ...
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2answers
386 views

leakage inductance on three winding transformer

I have a toroidal 3 winding transformer. It's a step up, lets say 1:10 ratio, the secondaries are identical. If I measure the leakage inductance, shorting 1 secondary at a time, I get about the same ...
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Transformer with diode to provide a battery backup

I have a small solar setup running with a low capacity battery plus a 100w solar pannel and i have 3 raspberry pi's getting juice from it. The thing is that sometimes with a cloudy day i can have my ...
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2answers
156 views

Characteristics of a transformer question

I'm trying to solve some problems and I'm confusing one thing . We have , let's say a 30MVA, 24.5/345 KV 3-phase transformer connected in wye-delta. I try to use one-phase analysis and want to find ...
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0answers
73 views

Diy arc lighter

I am trying to make an arc lighter, tried rewinding primary of ccfl transformer/inductor with only few turns and made my own with inductor I got from cfl circuit, they all worked fine for some time ...
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1answer
47 views

How do you find the phase lag of the current in this FM demodulation “discriminator” circuit?

I need some help understanding this discriminator circuit for FM demodulation. (L1, C1) is the primary LC tank which resonates with the carrier frequency, whose FM signal is applied at V12. As the FM ...
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1answer
43 views

Voltage divider resistor sizing to minimise voltage variance

I've got the following circuit design simulated in SPICE, this is a copy of the EmonPi circuit design (https://github.com/openenergymonitor/emonpi/tree/master/hardware/emonpi/emonpi_V1_6). I've got a ...
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1answer
53 views

Replace batteries with adapter for Christmas LEDs

This is related to a previous question. A box including 3 D batteries in a series configuration (4.5 V) is the power source of my set of Christmas LEDs. For these LEDs, I would like to design an ...
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1answer
63 views

Christmas LED lights connections

I have several Christmas lights with different AC adapters. First case In the label of one of them, I read: Primary: 220-240 V ~ 50/60 Hz Secondary: 31 V DC 3.6 W ...
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3answers
14k views

Why isn't a transformer a short circuit?

I'm a newbie with electronic components and I never fully understood why transformers, while essentially being a short-circuit from a wire perspective, don't act like short circuits (i.e. they don't ...
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1answer
102 views

How can a transformer convert the voltage of the same wire before and after connection?

Today I discovered a very strange thing, this transformer in the picture below, has 3 phases as input, and the output varies as you can see in the picture, the weird thing is that when I measure the ...
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2answers
2k views

Transformer maximum voltage rating specifications

I don't know how to interpret the voltage values found in datasheets for transformers. For example, in the datasheet below: where it says 15v, 50mA near the winding schematic. Is this a maximum or a ...
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3answers
366 views

Transformer and Thevenin Theorem

Consider an ideal transformer connected to a real AC voltage source (with output resistance Rg). Now consider to apply the Thevenin theorem between the output terminals of the secondary circuit. I ...
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46 views

Using three-phase transformer in reverse

I'm in the US and installing a 45 kVA 480 V/208 V transformer in reverse, to power an electric car charger that requires 480 V. The secondary of the transformer is in wye configuration and I will be ...
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2answers
62 views

Wiring a transformer

I have this transformer I have 240 going in and only 56 coming out should be 110. Is that jumper correct for 240? On other transformers for 240 i have two jumpers on the outside and when it’s 480 one ...
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1answer
470 views

Measure leakage inductance of flyback transformer with multiple secondary windings

I have a transformer consisting of one primary winding and 3 secondary windings. Now I want to measure the leakage inductance at the primary side, so I need to short the secondary windings. Most of ...
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4answers
119 views

Keeping a cheap, DIY transformer safe

I want to design a cheap but safe, low-wattage, always-on heater to keep a small space above freezing. (A small underground tunnel that the water pipe for an automatic horse waterer goes through.) I'...
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1answer
52 views

Why Doesn't the Current in a Transformer Diverge?

I just started learning about mutual inductance and transformers, and I haven't been able to find the answer to this question. I suspect it's really basic, and that I'm just missing some understanding....
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2answers
435 views

Enhancing the bass response of an audio isolation transformer

Below is a simple buffer circuit using an isolation transformer: The green trace is the output of the transformer and the blue trace is the input signal (20Hz to 20kHz sine wave.) As you can see the ...
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1answer
41 views

about the high voltage capacitor found in charger circuit

A while ago i have opened an electronic balance charger for a reason to try understanding how the circuit works so I've drawn the entire circuit for that purpose but i no longer have the drawing, but ...
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3answers
3k views

240V split phase and 240V single phase

All right, I don't get it. I tried and tried, but I just don't understand. I have a dozen questions about this so somebody just pick one out all of these, I don't care. What's inside a North American ...
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2answers
82 views

Simple current transformer strange waveforms

I'm trying to build simple 50Hz current transformer (just to see the mains current - maybe some microcontroller measurment in the future) following the answer to this question. When I connect it to a ...
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1answer
64 views

How bad is it to momentarily overload a transformer?

I have an espresso machine from the US running on a transformer in the UK. Inside the machine there is a grinder, a pump, and some heating elements. The machine is labeled 120VAC 1150W. I have it ...
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1answer
996 views

Modeling A Current Transformer in FEMM

I would like to accurately design and model a current transformer in FEMM. I'm hoping this will enable me to accurately estimate the secondary current in a current transformer, including it's phase ...
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2answers
146 views

Transformer Magnetization Flux

As far as I understand, an ideal transformer wouldn't show any net flux inside its core, as any such net flux would induce electric fields and in turn currents in the windings such that it will ...
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0answers
40 views

Spark Gap Circuit Creating Unpredictable Current Spikes, What is Causing This?

I have recently been messing around with bug zapper / spark ignitor circuits as a way to learn more about high voltage electronics (This is my first foray into high voltage territory other than a few ...
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2answers
303 views

How does the component “alarm boost three pin inductor” make a piezo buzzer louder?

I have a small circuit working on 2xAA batteries (3V) with an MCU and a buzzer for alarm sound. I've already successfully used an active buzzer (with build-in driver oscillator) drived by an NPN ...
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1answer
82 views

Identifying an unknown transformer

I was given an unknown transformer that I need help with. It has three taps on one side and 5 taps on the other. I was told that it was a 120 volt input transformer but when 120 volts is applied it ...
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95 views

Servo motor and EMI noise on peripheral devices (microcontroller)

I have 6 servo motors (DELTA ASD-A2-0121). Peripheral devices are affected by EMI noise (When motors are in on state and have no movement). I have changed the ground system from series mode to ...
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36 views

Why input and output power of chargers don't match [duplicate]

I know that battery chargers are more than just transformers (they are switched-mode power supplies), still, shouldn't input and output power be equal? Example: Input: 110/240V and 1.5A Output: 19V ...
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2answers
206 views

Create Transformer Center-tap From 2nd Secondary

After ordering this 200VA, 32V transformer, I realized that it doesn't have a center tap on each secondary, which I need to have. (duh on my part) So I want to use 110V across the 220V primary leads ...
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2answers
111 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
35 views

Coupled Inductor for DC-DC Converter ~50W

I'm designing a DC-DC Flyback or SEPIC converter, not decided yet. The converter is used to source some power LED's. The output voltage up to 60V and 1A with an input of 12-24V. The switching ...
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2answers
69 views

How can I design a clean system using 120 v generator, battery back UPS, and a reversed transformer to get a clean stable 220v with 30 amps? [closed]

This is a old question about design and I must of asked the wrong question. so here goes. Do I even need the Battery backup in this design and how does it affect the volts and total amps? looking to ...
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1answer
637 views

I have a Transformer Core - need help with winding/calculation

I have a microwave oven transformer which i had damaged in the process of removing the high voltage secondary. I will be using this for spot welding 18650 cells. I have all the required figures I ...
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42 views

How to generate an underdamped oscillation using transformers?

We want to generate an underdamped oscillation with a transformer, with this circuit: I am able to generate this signal: But I want to use a transformer instead something like this: What should I ...
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8answers
367 views

Transformer makes an audible noise with SSR but does not make it without SSR

I have a large transformer (see below) that I wanted to switch on/off from a digital platform using a solid state relay. The equipment works without any issue and makes no noise when the solid state ...
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1answer
472 views

Increasing the ocv of welder

Have a transformer welder with ocv of 45 volts. Wanting to Increase voltage from 45 volts to 75 volts. Is there a way to increase the voltage by adding another transformer with diodes and varistors ...
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2answers
626 views

Transformer to convert 220V split phase to 220V single phase

I'm a digital guy whose forgotten his "big wire" electrical education. I'm surprisingly unable to find a solid reference for this. I have a (European) 220V 50Hz split phase source (110V + 110V + GND)....

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