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.

learn more… | top users | synonyms

0
votes
0answers
26 views

DC Thump-like noise with Isolation Transformer

I put an isolation transformer inline with my audio (unbalanced 2 channel audio). It still makes noise when plugging the auxiliary cord in (kind of like 2 thumping noises) or when I tap the aux plug ...
3
votes
2answers
86 views

When/where to open and close a transformers output

I came across Beware of Zero-Crossover Switching of Transformers (TE Connectivity App Note) where they discuss about how you shouldn't switch a transformer at the zero crossing because it would have ...
11
votes
4answers
1k views

Can a transformer work if the core is not circular?

I am trying to build a transformer to convert 12V AC power to 5V AC. Here is what I have right now: I haven't adjusted the coil ratio yet but I tried it just to see if there would be any output ...
0
votes
1answer
24 views

Reading Current Transformer using Arduino

I want to be able to read current using an Arduino. I have purchased a Hobut Current Transformer from Farnell (Element14): ...
0
votes
1answer
45 views

What is the difference between a magnetized nail and a coil?

When I was a child, I brought a nail (metal bar) and I made some turns around the nail. It was something like a coil and the nail was the core of that coil. When I applied DC on the coil using 1.5 V ...
0
votes
1answer
66 views

Why is there a copper winding isolated from the iron core of my transformer?

Here is a picture of a 1970's arc welding station. There is a 9 inch bar of metal surrounded by 88 windings of 4mm copper, that used to be on the end of the secondary winding, which is made up of ...
0
votes
2answers
105 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 ...
0
votes
1answer
39 views

Reduce voltage after AC-DC rectification before step-down

I have a Weller Magnstat soldering station providing 24V AC to the tip. I want to use that output to power a 12V fan to disperse or absorb the fumes. With a cheap multimeter I measured 25V AC during ...
0
votes
1answer
58 views

Way to get high voltage from a watch battery

I'm creating a vary small device that need an high voltage around 50v. But because the device is really small like a pistol bullet, I can only use very small batteries like watch battery or button ...
0
votes
0answers
21 views

Modifications to Neon Sign Transformer to turn it into a variable DC power supply?

I would like to turn a neon sign transform into a DC power supply. Looking into this it would appear I need some rectifiers to turn the AC output into DC. I could use a variable resistor to adjust ...
1
vote
1answer
53 views

thermal knife power supply (part 2)

This is "part 2" because my original question has only brought up more queries that i am unable to solve. The first part can be seen here for any who are interested: "Hot-knife"/Thermal ...
0
votes
2answers
49 views

Transformer temperature rating

I'm building a power monitor (so I get notifications if the power is lost in one of the inputs). To monitor it safely, I used these 220/12 0.35VA transformers ...
0
votes
1answer
46 views

tube amp power transformer

I am trying to build a 18w amplifier based on this schematic however my power transformer doesn't have a center tap on the secondary winding Is it possible to use this power transformer for this ...
0
votes
0answers
41 views

Parallel operation of transformers

In a firm, two 250 KVA three phase distribution transformers (primary connected to same commercial line) are connected to different bus bars for feeding load. A bus coupler is also there with castle ...
-4
votes
0answers
46 views

Transformer design

I have designed a vp=115v,vs=62v shell type transformer. The secondary has two tapping of 62v each. The turns ratio according to my design should be 1.8. But the transformer after manufacturing is ...
0
votes
0answers
29 views

Transformer specifications to get 40V ac output from 210-250V ac in Proteus simulation

I want to design a transformer that connects to the ac main in proteus, steps the voltage down, and gives an output voltage of approximately 40 V. The core is made of f-type plates. The primary ...
1
vote
2answers
51 views

Impedance matching audio transformer windings

I want to create an isolation, impedance matching, balancing transformer for a DI box. I want it to work on Audio frequency and use a toroidal ferrite core. The input is an electric guitar, so it ...
1
vote
1answer
45 views

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 ...
2
votes
3answers
204 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 ...
0
votes
1answer
80 views

Old Radio RF Transformmers [closed]

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 ...
1
vote
2answers
79 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 ...
0
votes
1answer
49 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, ...
1
vote
2answers
62 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 ...
2
votes
1answer
44 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. ...
2
votes
1answer
48 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 ...
2
votes
2answers
467 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 ...
0
votes
1answer
43 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 ...
0
votes
2answers
53 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 ...
1
vote
2answers
95 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 ...
0
votes
0answers
48 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 ...
0
votes
1answer
47 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 ...
0
votes
1answer
52 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 ...
1
vote
1answer
46 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 ...
0
votes
1answer
33 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
votes
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? ...
0
votes
1answer
36 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. ...
0
votes
0answers
39 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 ...
0
votes
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 ...
1
vote
1answer
65 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. ...
0
votes
1answer
55 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 ...
1
vote
0answers
21 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 ...
0
votes
1answer
50 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 ...
0
votes
1answer
59 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
votes
1answer
57 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 ...
0
votes
2answers
42 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 ...
0
votes
2answers
66 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 ...
7
votes
2answers
357 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 ...
0
votes
1answer
45 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 ...
1
vote
1answer
68 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 ...
0
votes
5answers
129 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 ?