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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1answer
102 views

Why are tapped transformers needed in RF amplifier circuits?

I'm not really sure why, but I have seen many different RF circuits in which the input to a transistor is taken from a center tap instead of across the entire secondary, such as this example: Why is ...
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1answer
33 views

Altium->Coupled Inductors

Im glad to be with you. I have question about coupled inductors in altium. I want to make a flyback converter and tried first as in Image 1 . I converted 310V DC to 12V DC as you can see. I wrote ...
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How to step down 50kv to 300v (dc/dc) [closed]

I am thinking about stepping down 50kV DC to 300V DC - is it possible? 50kV dc 0.001 A Is there step down transformer with this voltage? I am ok with expensive solutions, but does zener diode help? ...
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3answers
102 views

Why can't I get transformer output as written on the label?

TLDR: I've made a short video about this, if you like looking at a video more than reading this. It's here: https://youtu.be/51235iFywI4 The problem is pretty straighforward. I have a (toroidal) ...
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42 views

How to convert 220V AC to 12V 500mA DC safely? [closed]

I want to make a converter that converts 220V AC to 12V DC. I have a water pump that pumps water out from a small fish tank. Which is rated 12V 8W. Can you help me with a circuit diagram? It will be ...
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2answers
163 views

How does this old fan regulator circuit work?

I was looking for an old fan regulator for a long timebecause a lot of people said that the power consumption of it was the same at high speed and low speed. This is a 50 year old fan regulator (...
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0answers
24 views

How do transformer winding strategies affect stray capacitance

I have a project that involves handwinding some rather compact transformers (toroidal cores about 0.5cm outer diameter; max number of turns on one coil of about 150), for which I am interested in ...
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3answers
1k views

How critical is winding a solenoid/electromagnet neatly?

We've all seen the expensive toroidal winding machines on YouTube, and manufactured solenoids are always so neat in construction - as in: Each winding is neatly packed to its previous, without ...
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1answer
47 views

Power In= Power Out in transformers

In transformers, we prove that the induced voltage per turn is the same in both primary and the secondary coils of the transformers, i:e (Ep/Np)=(Es/Ns). But when it comes to currents, we show that (...
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1answer
42 views

is it common practice to use transformers rated 50% over the load you want to use?

i designed a flyback power converter circuit with a transformer rated for 25 Watts, i expect to use all 25 Watts, is it common practice to use a transformer rated for 35 watts in this application? is ...
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2answers
36 views

Power recirculation rig using rectifiers and BLDC motors

I am currently trying to set up a rig to test my 3d printed gears under different torques and motor speeds. The power input side is going to be the BLDC motor, driven by a hobby ESC (BLHeli_32), ...
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1answer
21 views

Can you argue the current decrease along the two inductor pieces of a transformer using impedance?

I'm looking for a way to explain it other than using energy conservation/ power equal logic. in this we derive the relation between current in each coil by equating powers and then using the ratio ...
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1answer
33 views

Buck-Boost Transformer with Three Phase Wiring

I live in a residence with 120v / 208v electrical service. (Measured as leg1: 124v, leg2: 125v, 215v across legs) I am nearly certain that the service is the result of two legs of three phase power. ...
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1answer
50 views

Fuse on Primary Side of Transformer keeps blowing

I have a HVAC which is having a 24V 40VAC transformer. I might have shorted the output of the transformer while working on the wires. I noticed that the fuses on the input side of transformer blew ...
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3answers
67 views

How can current be in different phases in the same wire at the same time?

We know that either in ideal or practical transformer in no-load condition, the exciting current has two components Ic(core loss component) and Im(magnetizing component). Now since the same current ...
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1answer
62 views

It is possible to use a 100W 12V solar panel directly to charge a laptop, using a buck converter for example?

I am planning to go off the grid due to the pandemia, to an isolated village. I am working remotely I am looking for a solar approach to power my laptop ACER A5 515. The charger is rated 40W. I was ...
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2answers
57 views

how to transform 120V AC to 5V DC 5A load using flyback transformer circuit? Setting frequency - low cost, low footprint - change load capacity

i am using a flyback transformer circuit to keep the footprint small and cost efficient. Its been suggested to me to keep the frequency high so the transformer can remain small. how is the frequency ...
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1answer
56 views

Why will we get the wrong answer if we use \$I_1=\frac{V_1}{Z_1}\$ to calculate \$I_1\$ directly?

There is a transformer with \$600V/120V\$, and the impedance in the high voltage side is \$52-30j Ω\$, and there is a loading, which impedance is \$0.8∠10°Ω\$, connected with the low voltage side. ...
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2answers
54 views

Transformer vs SMPS for bench supply

One of the basic circuit to step down input voltage is to use a buck converter topology. Some power supplies reduce input voltage using non isolated type while others use isolated type (example use ...
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0answers
27 views

Clearance requirements from EGND to SGND on ethernet transformer

I have previously been instructed to have a ~70mil clearance between DGND and EGND and to bridge using a 1.5kV 0.47u cap. Application notes also show a 2kV 1000pF cap to EGND off of the center tap ...
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1answer
68 views

High open-circuit voltage in isolated push-pull SMPS?

I'm developing an isolated push-pull SMPS. I am attempting to transfer power through a custom center-tapped (on both primary and secondary side) transformer, stepping down from 20 V to 4 V. I am ...
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26 views

Reduce 50 Hz noise from robot-mower charger

I just bought a robot-lawnmower (Husqvarna Automower 105), which is working perfectly. But the charging station is making a loud 50 Hz noise all the time, even without the robot charging. I have ...
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1answer
24 views

Skin/Proxmity effects near transformer core

The above picture shows a rectangular wire carrying alternating current wound across a core with permeability much much greater than of free space(and also assumed is the fact that the width of the ...
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2answers
56 views

Full wave center tapped transformer output voltage

I have a full wave center tapped transformer circuit with input voltage of 220V How do I get an output voltage of 15V. What equations should I use ? Here is the circuit:
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0answers
33 views

How to calculate the current through load resistance in the given diagram?

I am here with yet another problem, where I have to find load current, ripple voltage, approx turns ratio? Also, any idea about how can we reduce ripple voltage further? Attempt: This is a step-down ...
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1answer
45 views

Voltage Divider or Step-down transformer for voltage sensing 240V AC [duplicate]

Hello I am trying to measure 240v mains AC as safely as possible. There seems to be 2 ways to do it, which of the two is better and preferred? 1. Voltage divider directly from the mains I have found ...
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2answers
62 views

Transformer Secondary Discontinuity

I am using a step up transformer and I am getting a weird discontinuity in the secondary output. Has anyone seen anything like this before? I cant figure out what might cause this. In a one test setup ...
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1answer
87 views

Transformer overheating reasons

I am currently designing a Flyback-based offline AC/DC converter similar to the following schematic (with a few changes e.g. sync rectifier at the output). Everything works nicely but the custom-made ...
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2answers
73 views

Is there any disadvantage with transmitting the same excitation signal to several resolvers (basically rotating transformers)?

I am considering sending the same excitation signal to multiple resolvers (i.e. transformers of which the secondary rotates with respect to the primary) used as angle sensors in the joints of a ...
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60 views

Building a voltage transformer circuit for sensing mains voltage

I would like to create a safe electrical circuit that measures the voltage from the wall (220vac). And the safest way that i know of so that when something fails there would be a high chance that my ...
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0answers
22 views

Troubleshooting adding a bluetooth receiver to my intercom system

I have a Nutone IMA 4406 intercom system with several intercoms throughout the house. I am interested in wiring a Bluetooth receiver to its Auxillary line in connection so that I can stream music ...
3
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1answer
137 views

Non-Ideal Transformer Equations

I saw the following non-ideal transformer in my textbook as an exercise. Find the equations for VA and VB. Then, find the required frequency of V1 with all elements such that the transformer is ...
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62 views

Wireless torpedo charger: Coil design and torpedo detection

I'm building an RC submarine with torpedoes and I thought a good way to power them would be with a capacitor. To keep everything water tight, I am hoping to use wireless charging. Here's a rough ...
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3answers
94 views

Center tapped transformer equivalent circuit model

What is the correct equivalent circuit model of an arbitrary center tapped transformer? i.e. I simply want the equivalent circuit model with has to look something like this: In center tapped the ...
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1answer
26 views

SM453229-381N7Y datasheet confusion/conflict?

I want to use this LAN transformer for my design but I'm getting confused by the datasheet. The electrical schematic section on the first page shows two images. One is a simplefied top view and the ...
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16 views

Webench coil selection for UCC28634DR AC-DC converter

I have being trying to design an AC-DC adapter for a freezer project I'm working with. After a couple of days researching I came across Texas Instruments Webench, which helped a lot. Although most of ...
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0answers
44 views

Temperature degradation of ferrite cores

While building smps halfbridge (old ATX similar) recently I went to a problem: When I use working transformer as a base drive one - it works good, but when I heat it up, unwind, and wind the same - it ...
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2answers
85 views

What does this symbol mean? And I have some basic problems which the book didn't mention

A power system book asked me this question, but honestly I don't understand the circuit of question and the solution which author provided. Question: There are 3 primary currents, \$I_R,I_S\$,and \...
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2answers
84 views

Relocation US to Germany: step-down transformer for TV, AVR, LED lights and other devices? [closed]

I hope this is the right place to ask this: I am relocating from the US (110V 60Hz) to Germany (240V 50Hz) and want to bring some of my electronic devices. It seems worth the hassle in my case (not ...
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1answer
26 views

ac/dc adapter input amperage rating

if you have a control circuit of 120V on the secondary side of a transformer which you have fused at 1.5 A since you are using a 150VA dry type and you connect a wall outlet plug in that 120V circuit ...
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0answers
76 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 ...
2
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1answer
103 views

Why can this ignition coil driver circuit not produce high voltage but only ~ 300 V?

Why is this ignition coil driver circuit not working correctly? (The coil is of this type, but used the model shown in the photo below.) The coil is driven with 16 V @ 5 A @ 540 Hz but I cannot get ...
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1answer
31 views

Energization angle of a transformer

I am trying to understand transformer behavior for a project that i am currently doing. I am trying to simulate characteristics of transformer using simulink models. In the various papers that i have ...
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1answer
87 views

What type of transformer is this? No other information on it. Thanks, just a newbie [closed]

This is in what we call a hole finder use in drilling stone.
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2answers
37 views

LTSpice, Current is not the same after going through identical step up and down transformers

I'm modeling my transformers as coupled inductors with appropriate values. I'm stepping up the current from my generator and then stepping it down at the load with identical inductor values (just ...
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1answer
69 views

Explanation request of a circuit involving contactors, transformer and a 3-phase motor

I found this circuit in a machine, I removed it and installed a VFD instead. This is how it works: when current arrives, the motor starts rotating, and the contactors K2 K3 and K4 close one after ...
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1answer
63 views

How to properly assemble a flyback transformer?

I have generated a transformer assembly project online for my flyback transformer. The Diagram: The Winding instructions: How do I connect the Primary First coil ...
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0answers
30 views

Why does increasing the load on the secondary coil circuit increase the current in the primary coil circuit [duplicate]

"Why does increasing the load on the secondary coil circuit increase the current in the primary coil circuit" This question is given as an exercise in my book. I can't figure out whether this is a ...
0
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3answers
63 views

When does the transformer equation hold?

The "transformer equation" is as follows, $$\frac{N_s}{N_p}=\frac{V_s}{V_p}$$ What is assumed when this equation is used? (Primary coil on the left, secondary on the right, in both cases) Is ...
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1answer
37 views

How to find out which side of transformer the OC and SC tests were performed?

I have this problem which states that in a single phase transformer 2200/110 50kVA No load and short circuit specifications are like below, How to find out which side of transformer were the tests ...

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