Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

1
vote
2answers
31 views

Grounding balanced secondary isolation transformer for EMI suppression

simulate this circuit – Schematic created using CircuitLab Which is the best secondary connection to clean the main line power from EMI, line noise and HF harmonics by using an isolation 1:1 ...
0
votes
2answers
34 views

Transformers: Short-circuit test

In a short-circuit test where the secondary winding is short circuited, how come the primary voltage isn't zero (in real life) when it should ideally be zero?
-1
votes
0answers
42 views

why does the peak open-circuit current increases nonlinearly whereas the applied voltage increases linearly for a transformer

Considering a transformer, the back-EMF equation tells us that the peak flux density is proportional to the AC supply voltage. Knowing that the current which flows in the transformer under open-...
1
vote
0answers
33 views

The resistance and magnetising reactance of the core

I did an experiment where I varied the test voltage and determine the values of the resistance and magnetising reactance of the core. What I noticed is that their values actually vary (not constant). ...
0
votes
0answers
19 views

How to use a singe transformer with the same effect as 2 in series

For a small project, I would like to know if it is possible to use a singe transformer, and a capacitor to effectively step up the voltage twice, E.g. Two of the same in series. If so, please explain ...
1
vote
2answers
94 views

Why are wireless chargers inefficient?

In the current market, the chargers are only 40-50% efficient. How much is the conversion and flux losses during transmission? Is there any way to improve the overall efficiency? Can a ferrite ...
1
vote
2answers
72 views

Electrical model of a transformer

I would like to know what is the inductance (circled in red) of this part of this model? Is the value infinite? And only the inductance (circled in blue) is the value of the inductance of the ...
0
votes
0answers
21 views

SMPS 5V without load, fluctuation on load TOP258PN

I am using PI Expert Online (this) to design a smps circuit for 5V, 2.5A output. I already have TOP258PN IC with me so built circuit for that. Change from schematics: I am not using choke and using ...
4
votes
0answers
43 views

Can somebody please explain to me the principle of a T-T Earthing system?

How are the transformer, consumer's side and the generator earthed in a T-T Earthing system? I seem to understand that the generator and its frame should be earthed separately; The neutral of the ...
1
vote
4answers
1k views

How can I safely determine the output voltage and current of a transformer?

So I am building a Tesla coil with my partner for a senior design project. We safely ripped out a transformer from a microwave oven. However, after a good amount of research, we were unable to find ...
0
votes
1answer
69 views

Peak open-circuit current and applied voltage of transformer function

I know that the back-EMF equation tells shows that the peak flux density is proportional to the AC supply voltage. But what is the explanation for that the open-circuit current increases non linearly ...
0
votes
3answers
57 views

Under open-circuit conditions, does a transformer behave more like a resistor, capacitor, or inductor?

I have the below schematic showing the equivalent circuit of a transformer under open-circuit conditions. Will the transformer behave like a resistor, inductor, or capacitor? And will this behaviour ...
-3
votes
0answers
39 views

smeltery Induction coil build increasing ac frequency and capacitor sizing [closed]

I'm building an induction coil and I'm wanting to know if a transformer will increase the ac frequency and if not what the best way of doing it as well as how to determine what size capacitors I need ...
0
votes
0answers
47 views

Current Transformers

I have a question about current transformers being used to measure AC currents. Say for example, we have a 50/5 amp current ratio, meaning that when there's 50 amps on the primary, there will be 5 ...
0
votes
0answers
59 views

Transformer rewind Schumacher charger

Have been considering rebuilding the transformer in an older 200A Schumacher (auto) battery charger/starter. Some time ago, the transformer itself began making an unsettling buzzing noise, then the ...
0
votes
0answers
22 views

What is Crossing, Overlapping in SMSP Transformer's electrical parameters? [on hold]

Some cheap ready made smps transformer sell on Aliexpress provide details about Primary's, Secondary's, Third's turn, and inductance on primary side. Some give No crossing, some give crossing, ...
0
votes
0answers
22 views

Led mr16 downlights flickering [on hold]

I have previous transformer with sec output: 700mA (const). 8.6 - 13VDC. Max 23V. Ta 50. Tc 80. I change the secondary output cable with MR16 cable and use it with philips classic led mr16 5.5 W. ...
0
votes
1answer
71 views

SMPS voltage drop in 230v ac to 5v dc flyback

I am building a SMPS circuit from a switching IC. This IC has feedback and enable pins for timing and current calculations respectively. Transformer Data: (10 pin 1-5, 6-10) primary: 1-3 - 60 turns, ...
1
vote
1answer
116 views

Why would a tube radio leave the 6.3V heater tap on the transformer disconnected?

I'm attempting to repair a Clarion C104 tube radio. I started the repair years ago, put it away, and now I'm giving it another attempt. When I started the repair, the transformer (Clarion part no. C80-...
0
votes
3answers
73 views

Confusion with impedance matching example using an ideal transformer

Starting from "The Effective Resistance of a Load Resistance attached to a Transformer" at page 8 of this document there is an example where it demonstrates impedance matching using an ideal ...
0
votes
3answers
55 views

Regulating VAC transformer voltage

Good day all, I was wondering if there are ways to stabalize the AC voltage between 220 - 230VAC (standard mains voltage in Europe) if the mains output voltage drops say for example 200VAC? I am ...
0
votes
1answer
58 views

Non-zero primary current under open-circuit test

Ideally the primary current should be zero under the open-circuit test. Could someone explain to me what are the physical effects corresponding to the two equivalent-circuit parameters that cause the ...
0
votes
0answers
22 views

How to calculate ripple voltage in power supply? [duplicate]

In my design, the input is 50Hz and 230V and output is 12.2V DC. I try to calculate ripple voltage with this formula [(1.01mA*10ms)/1000uF] but I can not be sure.How can I calculate ripple voltage for ...
4
votes
2answers
1k views

Voltage Balun 1:1

somewhere I have seen that it is possible to build a Balun by using a transformer in the following way: The explanation I have found is that the fact that the ground is only at the primary coil will ...
0
votes
2answers
95 views

How find the optimal frequency of a high frequency transformer

I have disassembled a "Chinese" power inverter, I found a High-Frequency Transformer, with no label on it. I would like to make an inverter using this transformer to generate the High voltage to feed ...
0
votes
0answers
39 views

220 volt ac to 12 v dc converter without voltage regulator

I want to design Additional RC Filter. My input is 220V AC and I want to observe 12 V DC output. I am designing 100 Hz with a full-wave bridge rectifier. My question how can I find the output of ...
1
vote
0answers
43 views

Core-less transformer for Zero-crossing detection

If possible, what are calculations and precautions involved in making a simple transformer without core? The only purpose of this transformer is to trigger an opto-coupler for zero-crossing detection ...
1
vote
2answers
39 views

Isolated Power Supplies for Inverter Gate Drivers

I am using a 3-Phase IPM IGBT Inverter Module in motor driver. This module has built-in gate drivers which require 4 Isolated power supplies for their operation. In all I have to design 5 Isolated ...
1
vote
1answer
67 views

Effects of multiple voltage sources in a transformer

What happens to inductor di/dt when you have multiple MMF sources such as the schematic of a coupled buck converter below? Specifically when D>0.5 so M1 and M2 are overlapping. What I would expect is ...
3
votes
2answers
360 views

What happens in the secondary winding if there's no spark plug connected?

The circuit below (minus the transformer and SCR) is used to detect the existence of a flame using the concept of flame rectification. Based on the circuit here: Pilot Light Flame Sensor I have ...
3
votes
2answers
1k views

Can't get 5V 3A DC constant

Here's the circuit I am trying to build. I want to get 5V 3A DC output but it's giving above 7V and 4A. I have checked it in the multimeter attached in the diagram. Can any one explain what's ...
0
votes
1answer
56 views

120v to 24v 40va transformer damaged, replaced with 120v to 24v 15va transformer [closed]

Powermaster J51 electric gate motor tested, working. Problem is that remote relay does not engage despite new transformer. If the relay is helped (manual push) it will engage and remain engaged until ...
-2
votes
1answer
67 views

Non center tapped transformers [duplicate]

I accidentally purchase a larger 24vac transformer Primary 120v/208v/240v Secondary 24 Output 40VA 50/60 HZ This transformer is not center tapped. Rather has only 1 green and 1 red wire on the ...
-1
votes
2answers
85 views

What amp rating of 24vac transformer for LM317T

I am trying to post a new question about the lm317 to-220. I just want to know what size transformer for lm317 at full 30vdc. I know its a 24vac center tapped transformer but is it 1 amp or 5 amp ...
0
votes
1answer
78 views

What should be the Winding at Primary and Secondary in Transformer?

I am trying to build this circuit and testing it in Multisim. As you can See this circuit Produces between 12V-14VDC with 10A but the transformer used in this, I am not been able to get it's Primary ...
0
votes
0answers
34 views

Transformer primary winding splitting

UCC2863x, High-Power Flyback Controller with Primary-Side Regulation and Peak-Power Mode In a design of a fly back converter the transformer used has 3 windings i.e. primary 328 μH and ...
0
votes
2answers
70 views

Why does the voltage regulator not regulate when ac is around 200V AC?

So the voltage regulator works well when the input of the primary winding transformer is at 220V or greater and the 12V regulator does output around 12V. Why is it that when I turn down the variable ...
0
votes
2answers
40 views

Three phase step-down transformer

I am using 415 V supply. Line to phase neutral is 240 V. I have 110 V appliances that I want to use. I have created 11 different points for which I want to use this appliances, and want ...
0
votes
2answers
72 views

Could a blown voltage regulator still supply electricity?

(I'm new to electrical engineering, both the website and the topic, so don't hesitate to correct me) I'm building a very tiny form factor transformerless power supply with 5 V output. I was ...
0
votes
0answers
48 views

Power Supply for the Pre-amplifier I bought

I bought this China clone "Marantz-7-M7-Tube-Buffer-Audio-Preamplifier-Pre-AMP-Board-KIT" I thought that it was just simple. I just don't want to throw it away, but what does 220v mean input meant in ...
0
votes
1answer
41 views

LTspice stacks data points on the same vector when I do linear parameter sweep

I am trying to export the voltage of a transformer for different mutual coupling values. However, when I do a linear increase of mutual coupling it seems that LTspice will stack the parameters in one ...
1
vote
0answers
46 views

Transformer/Inductor Bobbin Sizes

I have to design a 150 Ampere, 1.5 mH Inductor for a power supply project assigned to me, and off-the-shelf components are to be used. My instructor is insistent on using a transformer Bobbin to wind ...
0
votes
2answers
36 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 ...
0
votes
1answer
32 views

Is it possible to determine a low power isolation transformer maximum output current?

I have a transformer (no codes) 240vac to 12vac this is easy enough to determine but what about the maximum current? 1) I could load it until the voltage drops but to what exactly? 2) Is there any ...
2
votes
2answers
53 views

Ideal LC circuit decays over time in LTspice

I was trying to simulate a transformer without a load, and setting an initial condition to observe how the energy will flow from the primary to the secondary circuit. I realized that the energy will ...
0
votes
0answers
52 views

Replacing AC transformer

I've encountered a problem while replacing the AC transformer of a soundsystem composed by 3 loudspeakers (1 bass loudspeaker (4Ω5W) and a couple of highs(can't open to see the specs of these)) and a ...
0
votes
0answers
33 views

Identify relevant parameters of Transformer Spec. for Audio Application

Upon the advice of this question/answer I have added a 1:1 audio isolation transformer to my circuit. I picked up a transformer at the local radio service shop and dropped it into my bread-board ...
0
votes
0answers
52 views

Individual Three Phase Potential Transformers vs Three Potential Transformers in one case

If I had to select between Individual Three Phase Potential Transformers vs Three Potential Transformers in one case for a 600V system (which doesn't require many inches of spacing between phases to ...
0
votes
1answer
51 views

How to connect a 3 phase 240V machine on a 415V supply

I have a challenge in connecting a 240 V 3 phase 9kw machine to a three phase 415V supply in Uganda. The machine is from South Korea. The phase monitor trips. Below is the brief precaution ...