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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3answers
46 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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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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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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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
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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
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
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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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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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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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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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3answers
38 views

Why is the transformer secondary winding voltage higher than expected?

I am replacing a faulty 110-to-220V AC transformer: The new transformer is a Bel Signal A41-130-230. It has a little higher VA rating (130 instead of 80) and also features dual primary and secondary ...
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1answer
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N50 347Y Transistor? High-voltage transformer circuit component

recently came across a 15kV inverter for a DC high-voltage transformer kit that comes with the attached circuitry. I already have most of the components on hand, though I am unsure on what the 'N50 ...
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1answer
204 views

Why is my homemade pulse transformer so inefficient?

I built this transformer core out of 30 mm mild steel. It is 13 cm by 8 cm. The primary winding is 30 meters of #29 wire, and the secondary is 60 meters of #29 wire. The windings measure 5 ohms and 10 ...
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Transformer hum coming in audio amplifier

I made an audio amplifier with a 6283 IC. When I power the amplifier with a 12V battery it works fine without any hum. When I power the amplifier amp with a 12V powered transformer, hum comes from ...
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coupling coefficient & effective turn ratio

In the fundamentals-of-power-electronics this book, Chapter 13 Transformer Modeling How to derive the coupling coefficient (13.52) & effective turn ratio (13.51) I can use the ideal transformer ...
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2answers
81 views

Why are microwave oven transformer laminations not insulated?

I know that it is a peculiarly designed transformer, but I never found any explanation (and nor even questions) about that before. I know that soldering the lamination in the edges for instance won't ...
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1answer
32 views

Regarding plugging operations

For an induction motor that runs with negative slip value, is it true that the plugging operation occurs when an induction motor runs with negative slip value?
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Power and current contradictions in transformer secondary

Two contradictions that I couldn't find a solution for regarding a transformer: For an ideal transformer, from conservation of energy we can say that: V1 * I1 = V2 * I2 Where V1, I1 are the primary ...
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67 views

How can I connect mains to a 230V heating band?

I am planning on using some 230V heating bands for a project of mine. I was wondering what kind of equipment I would need to connect this heating band, which has +,- pins to mains. What kind of ...
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Can I meet NEC class 2 or 3 requirements by fusing a 120v circuit at 0.5a?

I am installing a device that operates at 120 VAC, and I wish to use a class 2 wiring method. The device is rated at 0.1 A, and I want to know if I can simply fuse a 120 V circuit to meet class 2 ...
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1answer
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How to calculate number of turns, N for a gate driver transformer?

Update: Hi, my TA helped my issue. Thanks for everyone's help. It turns out, my area should be 12.2e-6.(I accidently wrote 12.2e-5). And, my understanding for ∆𝐵=2Bmax was wrong. The right way for me ...
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1answer
44 views

AC zero Crossing detection with transformer

I am working on a circuit that requires zero crossing detection. I detected the zero crossings of the 230 Volt AC sine with the help of a full bridge rectifier and a 4N25 optocoupler with a pull up ...
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1answer
118 views

Do ordinary transformers need flyback protection?

Low voltage 12V relays driven by a microcontroller plus transistor need a flyback diode to suppress an inductive voltage spike when they are switched off. Do ordinary power transformers (say, at a ...
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1answer
36 views

How do you wire a transformer for multiple output and amperage?

I'm getting different answers watching the MOT (Microwave Oven Transformer) videos on YouTube. Some leave the shunt out, some leave it in, etc... I have a MOT and want to make a 12VDC power source ...
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1answer
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i have problem with capacitor discharge ignition circuit CDI

i have a hard time to understand what is the problem in this circuit, can someone help please, i have a Moped with its capacitor discharge ignition Box work fine, the spark exist, but i wanted to make ...
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1answer
45 views

SMPS transformer secondary voltage drift

Please see the simple SMPS buck circuit below (24V to 12V) Notice the load on the 'first' secondary coil is about 100mA (marked 'fb' This coil is used as the feedback to the MC43063 to regulate the ...
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1answer
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How to correctly use the formula for calculating the air-gap in a pulse transformer?

To achieve a certain value of the magnetizing inductance (Lm), we can adjust the transformer air gap. Air gap calculation formula: There is no particular information on this, but I assumed that: <...
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2answers
75 views

Identify the tip polarity on this AC adapter without plugging it in

I have a 230V AC-DC adapter/transformer from Europe that I am trying to replace with a 120V version. I am trying to determine the tip polarity of the DC output. I cannot simply plug it in and use a ...
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1answer
51 views

Relationship between input power and output power of a boost converter and transformer circuit

simulate this circuit – Schematic created using CircuitLab I have a few questions regarding variable power supply units powering boost converter circuits with transformers and the relationship ...
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How much self induction would each coil of a transformer of one to one ratio be if the kVA rating for that transformer is 160?

Assuming a current load of 80 A, and a voltage load of 1600 V, the straightforward kVA rating would be 128. But adjustments are made for power factor correction and other considerations raising the ...

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