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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Toroid Core Selection for Audio Isolation Transformer

I am a newbie. I have attempted to make an isolation transformer with some toroid cores and it worked, but not well. I tried using a "wide band" toroid core and it seemed to have killed a lot of the ...
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3answers
130 views

“Hot-knife”/Thermal cutter power supply design

Im undertaking a DIY rope cutter project to avoid paying for the ~$150 storebought ones. Many resources online told me to use a light dimmer + transformer configuration and i had planned to go a step ...
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1answer
71 views

Old Radio RF Transformmers [on hold]

I want to make a TV transmitter (http://electronics-diy.com/electronic_schematic.php?id=851). There is an RF transformer on it (T1:4.5MHz 1F-can-style RF transformer) that I want to find it from old ...
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2answers
73 views

How do I identify the imput side of a transformer

I have this 2.5VA Split-Bobbin Power Transformer 115/230VAC. According to page 3 of the Data Sheet (PDF) it looks like there is a line on the "DSW" version on the pin 1-4 side. This seems to ...
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0answers
40 views

Transformer kva to size? [on hold]

I've recently started a job where I need to identify transformer KVA based on size from pictures. They are usually noted in the software but I also look at pictures. Is there any practical equation ...
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1answer
42 views

Powering a Futaba S3003 servo

I'm working on a project and I need to use a Futaba S3003 servo, I'm about to buy a transformer that gives 6v, the thing I'm not sure about is the amperage. Is this transformer ok? I can choose 3V, ...
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2answers
52 views

About “leakage inductance”

I'm a little confused about the transformer "leakage inductance" for days. Per this text book, it gives a schematic view of fluxes flow in the transformer: It's apparent that the two leakage flux ...
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1answer
41 views

About the leakage reactance of transformer

As known the transformer's equivalent circuit can be developed as below: Assume the \$V_{1}\$ is the voltage applied to primary side, and \$V_{2}\$ is the voltage developed at the secondary load. ...
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1answer
45 views

Transformer Efficiency Issue

Trying to improve on the transformer efficiency, I changed the configuration of the rectifier from half wave to full-wave. Below shows the configurations I used Transformer turn ratio is enough so ...
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2answers
428 views

transformer has continuity but no voltage output?

I have two old transformers that appear to be fine, however no DC voltage was measured on the secondary coil. I have measured: The input voltage: 229 AC the input coil ohms: 0.015 kOhms the two ...
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1answer
38 views

Confusing transformer winding, what is it and can i change it?

here are two 380V to 24V/48v transformers that weigh 10 pounds each. I was hoping i could get 15V with 500w out of one at 240V and measure the welding potential. the secondary winding uses 0.5mm ...
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2answers
37 views

controlling a DIY spot welder with a momentary push button switch?

I have a 240v to 12v transformer even bigger than a microwave transformer and i want to control how long it is switched on for in the range of 50-300 milliseconds to spot weld things. I was thinking ...
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0answers
38 views

Getting 21v on 24v transformer output [on hold]

Transformer for power shower: 230v step down transformer to 24v. Reads normal on supply side, output showing 21v, is this normal? There's no power in the shower. Is it possibly a fault with the ...
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2answers
89 views

Why does this transformer draw so much current?

I've been working on a DC power supply to provide about 10 mA at 200 V. The simplest way (not dealing with a switching power supply) seemed to be using a transformer to step 120Vac up a little bit to ...
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0answers
45 views

How to Use Current Transformer

I have the the 3110-3000 CT: http://www.crmagnetics.com/Assets/ProductPDFs/CR3100.pdf What I am trying to do is get the current value in a wire, and the raw reading I get is consistently 1495 for ...
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1answer
41 views

Good way to switch AC/DC (Rectifier) in welder

I am building a homemade welder out of microwave oven transformers. I would like to have ideally an on off switch and then an AC/DC switch or just having one switch would work too. AC 120V 60Hz ...
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1answer
40 views

This circuit has floating nodes in LT Spice?

This is the circuit I'm working on. This circuit probably doesn't work as intended to begin with, but that's not the point. LT Spice keeps complaining that it doesn't have a reference to ground. I ...
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0answers
32 views

LT Spice and inductors parallel to AC voltage sources?

This is a circuit I designed in LT Spice. There is no transformer component in LT Spice so I specified L1 and L2 as magnetically coupled with K L1 L2 1 when I try ...
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1answer
23 views

Two windings transformer to autotransformer

Let's say that we have a transformer with two windings with nominal power \$S\$, nominal voltages \$V_1\$ and \$V_2\$ and windings \$N_1\$ and \$N_2\$ respectively. The equivalent impedance is ...
3
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1answer
144 views

AC circuit with unusually placed transformer

Here's the circuit: simulate this circuit – Schematic created using CircuitLab $$I=2.25,0° mA$$ What's the $$n=N1/N2$$ of the transformer so that on R3 most power is dissipated. Power? ...
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1answer
35 views

Transformer showing unexpected values

I have setup a step down transformer to transform my 115v AC down to 5v AC. I ordered a transformer and hooked it up in parallel (there are two coils) and my oscope is showing 10v on the output side. ...
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0answers
32 views

Determinate Area of a E-I core?

I have a transformer which I extracted from a receiver I want to reverse engineer it and calculate the values its values. As far as I know some site for example says that the calculation formula for ...
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0answers
45 views

Rectified voltage less than AC, what could be the problem?

simulate this circuit – Schematic created using CircuitLab V1 = V2 = 251VAC V3 = 502VAC V4 = 112VDC D1, D2 are BA259 rated at 1kV. What am I doing wrong with this center-tapped ...
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1answer
61 views

I don't understand transformer power ratings

I'm befuddled. I have a wall wart power supply that supplies 65W (it's for an Intel NUC). I'm interested in building my own power supply that will put out... several different voltages and currents. ...
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1answer
52 views

How does an electronic shocker works?

I'm new to electronics but I want to make this diagram from "Instructables" : I have everything I need from a camera... I also realized, using a different transformer, that the sparks are made only ...
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0answers
19 views

Question about transformer reflected source

The following show the idea how a Thevenin equivalent source is used to replace the primary circuit of transformer. In textbook it is commonly stated that the load impedance sees an equivalent ...
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1answer
45 views

Step down transformer

I have a 12Volts, 2Amperes transformer and I need a lower voltage and lower current power source for my other components. I want to know how to make a step down transformer i want to lower it up to ...
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1answer
57 views

Inductor in transformer

In an inductor, a current waveform 90° out of phase with the voltage waveform creates a condition where power is alternately absorbed and returned to the circuit by the inductor. If the inductor ...
2
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1answer
44 views

How to read this transformer label

I have the following transformer that takes in 117V and steps down to 12V and 9V. However, I don't understand the label. "PUR" and "RED" are listed as 117V, does that mean PUR is power and RED is ...
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2answers
36 views

Transformer turns and effect on frquency

What is the relation between transformer turns and frequency of input? I hear there is a transformer coupling in stratix 2 FPGA. I went through the data sheet and found the lower cut-off input is 400 ...
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2answers
64 views

Adding up Transformer Output

This Question is regarding to Transformer Power Electronics. I attached two transformers - one is Step Up (220V ; 0.5A) and another is Step Down (6V; 20A) to a same power source (25V ; 5A) in such ...
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2answers
344 views

Which Earth should a chassis be connected to: supply, or local?

I have a doubt regarding the earthing of an appliance and its separate isolation transformer. Consider the following simplified schematics; this is my first guess at which earth each chassis should be ...
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1answer
44 views

Potting transformers for mechanical noise reduction

Potting some noisy transformers failed to reduce the sound. My question is where the problem might be. The setup is a row of small (about 0.75x2x4 cm) transformers on a PCB as part of a power ...
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1answer
62 views

Can't find a high power linear power brick? [closed]

I've searched for quite a while, so I'm fairly sure I'm not doing things right. I need someone to point me in the right direction as I'm sure there's a better option. I'm looking for a highish power ...
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5answers
123 views

Making a 15V transformer

I presently have a transformer with 12V DC output.But I want to charge a 15V battery.So how can I make the 12V transformer to 15V ?
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1answer
52 views

DC batteries connected to multiple-core transformer

My understanding of transformers is that they take in and give out AC signals. However, the UPS system below has its DC batteries connected to a transformer. Is it possible to know the rational ...
0
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3answers
118 views

What is this on power supply unit?

I need to power a large 180W LED lamp that runs on DC so I got this transformer that is 12v × 15amp. But I don't understand the labeling on the terminals. There are 2 +V terminals but no -V ...
2
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3answers
73 views

Why is transformer higher voltage primary usually closest to the core and has the shortest loops?

AFAIK the typical transformer design includes the primary being wrapped closer to the core and the secondary being wrapped atop of primary and so further from the core. Why this way and not the other ...
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1answer
67 views

What's the thick wide aluminum tape used for in last mile grid transformers?

This YT video (scrolled to 0:45) shows the process of fabricating a pole mount transformer. At 0:45 the following is shown: there's a wooden brick used to hold everything together, it's covered in ...
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1answer
72 views

Wiring a step down transformer

I have a Transformer with the following writing on top of it : TFM-00053 CLASS B 130°C Z150H E154515 LEI-4 8B25 it has three thick wires on one end : Blue Brown Red ; the resistance ...
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2answers
55 views

Voltage on the secondary of current transformer

We know that current transformer is used to step down the current of the primary side. So basically it is a STEP UP transformer. Also we say that current transformer basically works on close to short ...
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1answer
36 views

How to measure ratings of a transformer

If I am given a transformer without any datasheet of it. Then how can I measure the maximum current and voltage rating of the transformer?
1
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2answers
36 views

Can a planar transformer replace a laminated transformer for 50Hz AC conversion?

I have seen planar magnetics transformers even with isolation up to 20 kV. However those devices seem to be designed for DC/DC conversion in 100 kHz range. I am wondering whether low frequency ...
0
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1answer
102 views

D.C power supplies, regulated linear power supply question

Design giving the necessary ratings and characteristics the necessary for the transformer, bridge rectifier capacitor and regulator , a 12v , 2A regulated power supply . the available mains supply is ...
0
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1answer
38 views

Voltage transfomer without ground connection

today i bought a transformer 200v to 110v for my soldering station hakko fx-888D however it doesn't have a ground connection. Is there any problem if i connect the soldering station to it?
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0answers
45 views

Wireless powered power line robot

I'm trying to make a small robot with a camera that can run on a hanging wire outdoors. I've been thinking of ways to power it such that I would not need to pull a tether around, need to recharge ...
0
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2answers
74 views

What is the best way to serve AC power to a 12v - 5v DC regulator with 1Amp current?

What transformer should I use to supply AC voltage in a circuit which is using 7812 and 7805 - Positive Voltage Regulators. I need approximately 1Amp current. What is the best way to minimize the ...
0
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0answers
35 views

Angles of phase displacement between phase and line voltages in star connected transformer

I recently did a lab in class which required using an oscilloscope to measure the phase difference between the line and phase voltage of a star to star connected three phase transformer. Two of the of ...
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2answers
178 views

How to position adjacent transformers so they don't interfere?

Using a couple of 240V mains step down transformers, undecided whether to use E/I laminated or toroidal, one 22VA the other 7VA. How to mount them in the case, so that they're not affected by each ...
0
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1answer
67 views

Shorting leads on centre tapped transformer

I have an audio transformer (SP-66) with a 1:1 ratio and centre taps on the primary and secondary windings. Tests: When I input a 6.5 kHz 8 Vpp sinusoid on the primary (pins 1 & 3), I observe ...