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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44 views
12VAC to 12VDC Converter Requirements for RGB LED Controller
I have an outdoor lighting transformer (operating at the usual 12VAC) that I want to add a strip of LED lights in a new run. The transformer has two legs, each ...
1
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1answer
45 views
Flyback converter
I am designing a flyback converter based on the UC3844 chip. As a starting point, I went through an eval board that is given in the Microsemi website. The schematic of the design is as shown below -
...
5
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4answers
2k views
Why can't you use a coil to transform 5 volts DC to 12 volts DC?
Why can't you just use a coil transformer, like when you want to get 240 volts out of a car battery instead of a boost converter? I found a thread that sparked my interest - How to transform 5V into ...
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0answers
49 views
Design of my Current transformer [on hold]
With the risk of all going wrong and that I might not get a happy answer, I'll fire the question anyway. Circular design.
My main concern (I think) is of size. So,
inner diameter: min 10mm
outer ...
0
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0answers
59 views
Magically inverting voltages. Why does my circuit output a negative voltage where I expect positive?
I modified a disposable camera flash circuit to power a Geiger tube at 400v with 5v on the input. The whole circuit works perfectly, but I've encountered a strange phenomena. I wired it up and hook it ...
3
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3answers
112 views
Could sawtooth waveform be optimal for transformer input?
All the transformer theory I have reviewed uses sinusoidal waveforms, and concludes that a true sinusoidal input is optimal. But I'm wondering whether a sawtooth waveform would actually be optimal in ...
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2answers
39 views
Voltage across transformer primary to secondary - ways to mitigate
I am trying to galvanically isolate my electronics from the Mains and isolate Earth, so have placed an isolation step-down transformer (230:20) in between the Mains and my electronics.
If I measure ...
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2answers
36 views
Transformers and impedance matching
What I have learned: In a ideal transformer, the power in the primary circuit will equal the power out in the secondary circuit.
Impedance matching: if I take the turns ratio of the transformer in ...
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2answers
68 views
Need approval of transformer driver design
I designed a circuit from several ideas I saw before and I'm a bit too impatient to build the thing myself.
(http://imgur.com/KD97NuJ)
Basically, it's a two-transistor oscillator combined with an ...
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votes
1answer
35 views
removing the 180 degrees phaseshift at the secondary of transformer
me and my group are designing a PMU(phasor measurement unit) prototype.we need to step down the 220v AC input upto 12v by a t/f.till here everything goes ok..but PMU is meant to measure the phase ...
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0answers
39 views
Arduino light switch transformer
I'm building a light switch with an ATMega328 (Arduino) which needs 5v. The light switch will be integrated in the wall where a 220v power line is present. I would like to power the Arduino from ...
0
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1answer
37 views
Confusion about induced EMF and voltage in Ideal Transformer
When an IDEAL transformer primary is connected to an AC source, an EMF will be induced in the primary given by
$$E = N \dfrac{d(flux)}{dt}$$
And it must be given sign by Lenz's law. So it should be ...
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0answers
10 views
Dry Type E-I CRGO Lamination based 5KVA 3 Phase Transformer DELTA-WYE Winding Turns Calculation
I am basically a firmware developer so pardon my ignorance.
I need to construct a 3 Phase 415V/50Hz DELTA Input Transformer. The core is 1.5 TESLA Max (as per stockist). I need open ended ...
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2answers
52 views
Can we proof a scavenged transformer of unknown specification?
This step-down transformer was scavenged from a power tool battery charger. It was designed to take 120V AC current and it outputs 20V AC.
I can't find any specs for it, so I'm wondering what ...
2
votes
1answer
41 views
Induced voltages and flux within a transformer and their polarities
This is a multifaceted question, and is more to see if I understand what happens inside a transformer. I understand the general idea behind transformers: Alternating voltage that is applied to the ...
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0answers
47 views
Selection of transformer
I am designing the model of substation of 150 MW. But I have confusion in selection of transformer.
As per design a rating of transformer is 180 MVA. But I need to know about that whether I use three ...
0
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1answer
43 views
would i need a fuse when experimenting with transformers?
I have a 0.7A center tapped 12v/15v transformer(i dont know details about it). However i dont know which pin is which among the output pins, so I have to jump them in many ways and measure with ...
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0answers
35 views
Putting together a flyback converter development platform
At this stage of my independent study of off-line flyback topology switching
converters, I'd like to start building some working converters to get
a hands-on feel for things and to perform ...
0
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1answer
29 views
putting 15 vct transformer in series to get 30 vct output
i have this 15 vct transformer.
as you can see, it's 15v 0v 15v center tapped transformer.
I want to make these two transformer behave as a 30 vct transformer.
then, in this picture, is A 30V and ...
0
votes
2answers
47 views
can i connect wires in a single transformer to get higher volts?
I have this transformer, and i want to get 27V output. i don't know what's inside, but i just have the product. it's a 15/12/0/12/15 vac center tapped transformer.
The question might be dumb, but ...
0
votes
1answer
83 views
What will happen if I connect a 9v ac input with a step down transformer (80V ac to 24V ac)?
I'm doing a university project and we're not allowed to use mains. Hence, I planned to use a 9V input and step it up to 24V.
However, I couldn't find any transformers online which have a 9V ac input; ...
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0answers
62 views
Is it possible a zigzag grounding transformers made from single-phase 220:12 transformers?
We have 20 transformers 220:12V rated 2 A in stock. We want to make an experimental zigzag grounding transformer to reduce the third harmonic current injection from single-phases, slightly unbalanced, ...
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1answer
38 views
Transformer control using a MCU
I am trying to generate 12V output using this transformer. From the datasheet it states that Vin can be 20-48V at 150kHz. Now, I am trying to send a pwm to a MOSFET that will control the connection to ...
4
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3answers
253 views
Why does a UPS need an isolation transformer?
Why would we need isolation transformers before and/or after for a UPS system? What are we trying to protect, and from what? I have read that it has to do with grounding and neutral but I didn't ...
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0answers
28 views
Proof check my solution to a single phase transformer problem
I will show you my solution to a transformer problem. I do not have the key and I am not sure if my solution is correct.
A single phase transformer of 10 kVA, 500/100 relation, \$Z_1=
0.2+j0.4\$ ...
0
votes
1answer
40 views
How to claculate LM-723 regulator circuit headroom above the intended output voltage
I need to calculate the transformer VA for bipolar regulator circuit using LM723 so I need the voltage drop or may be a headroom for LM723 under load. The data sheet is silent about it. Is there ...
0
votes
1answer
40 views
Transformer input voltage
i have a transformer with 0V and 220V(neutral to line voltage) in the primary side. I want to know if it is possible to use a 220V single phase(line to line voltage) as input in the primary side? ...
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5answers
158 views
Can't find the right power supply - could I use something similar?
So I've just bought a Behringer MX2642A mixer off eBay, which worked for two hours then promptly shut down. After investigation, it seems that the power supply might have given up - the specs for the ...
0
votes
1answer
59 views
Pulse transformer isolation on PCB
I have a question about pulse transformer ,regarding to isolation, EMI reduction and heating.
My PCB has 6 layers (4 signal and 2 power planes) and I am using pulse transformer to isolate and convert ...
0
votes
1answer
35 views
Measuring the inter-winding capacitance of a multi-coil transformer
I want to measure the inter-winding capacitances of a multi coil/winding transformer. (To use them in a simulation)
For a two winding transformer I would measure it by shorting out the individual ...
3
votes
2answers
47 views
How signficant is leakage inductance in a flyback converter?
In designing some flyback DC-DC converters (to give us isolation), we have been simulating potential designs in LTSpice, which has gone well. (Isn't LT great at documentation? Pretty much perfect ...
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3answers
127 views
How to: The basics of transformer VA calculation for voltage regulation using full wave rectification
Likely this procedure has been repeatedly discussed here. But I want to put the pieces together in this certain domain.
So let's say we need to get +/-12V at the outputs rated at 1A using classic ...
0
votes
1answer
28 views
Ae parameter for different transformer cores
I am trying to select a transformer for designing a dc dc isolated forward converter. Now, I see in an example a core of ETD34 (AN 2013-03 application note from infineon,page 5).
Now, as partof the ...
2
votes
1answer
59 views
type of transformer shown in a document
I am designing a dc dc isolated forward converter that accepts 20V and outputs 10V(Imax of 5Amps). As part of the study I was reading this document
Document
In the page 15, it shows a transformer ...
0
votes
1answer
68 views
100Hz noise from a mains transformer
I bought a new speaker and it hums even with volume knob turned to 0. After opening it up, I noticed it was the iron transformer oscillating (and screwing it tighter does reduce the noise).
How is ...
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1answer
46 views
30-0-30 ACV 8A transformer to 12DCV [closed]
Good Day..
I have a 30ACV 8A transformer. I urgently want to make a 12DCV battery charger from it. What are the components that I should use? Please also help me out with its schematic. Your help ...
10
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2answers
2k views
Why do laptops need larger transformers than mobile phones?
I was wondering why a laptop power adapter is so huge. Most laptops that I have seen use a ~19V power supply. Using transformer equation, and considering 100 turns in the primary(just an assumption), ...
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1answer
46 views
Will a 110-220v to 12v converter work with a DC 12v 3w LED bulb? [closed]
I'm planning to create some wall lights using these LED bulbs. Would I be able to just use any 110-220v to 12v converter to power this at home? I live in the US (120v).
I was thinking of using this ...
1
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2answers
70 views
35v reading on 24v transformer
im troubleshooting a 24v ac transformer hooked to two doorbell circuits and on one of them I am getting a 35v reading. What could be causing this?
I am reading the voltage using a standard (cheapo) ...
3
votes
3answers
50 views
How to I calculate the AC amperage draw of a 12 volt 3 amp AC/DC transformer under full 3 amp load?
I want to calculate the 120 volt amperage draw of my 12 volt AC/DC wall adapters, most specifically, one that has a 3 amp rating that is pulling close to 3 amps.
Is there a formula for calculating ...
0
votes
2answers
60 views
Finding Vout of a Transformer
I am a little confused on how to read the ratios of a transformer
Suppose there is a ratio of 1:6, is this read as the following?
Number of turns on Primary: Number of turns on Secondary?
so suppose ...
3
votes
3answers
144 views
How to overcome transistor heat in slayer exciter?
I build this circuit and it works but I have two problems. The major problem is that the transistor becomes very hot quickly. I burnt my transistor due to excessive heat. How can I get rid of the very ...
0
votes
3answers
84 views
How to correctly wire this transformer for 240V?
I have an old transformer (without any details about brand and model) with dual primary windings. I need to set it up to take 240V, but I am unsure about the correct way to connect the windings in ...
0
votes
2answers
48 views
Is an ideal transformer an ideal current source?
I define every circuit element of a primary coil of a transformer that is connected to a voltage source and calculate \$I_1\$ (current of the primary loop). I then connect it to a secondary coil with ...
0
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1answer
67 views
Ideal transformer output voltage
I know that the output voltage and current of an ideal transformer depends on the number of wounding of the coils. It means that no matter how many resistors I put in a series in my secondary loop, ...
10
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1answer
486 views
What does a black bar across transformer symbol designate?
What does a black bar across a transformer symbol designate?
This appears in a power electronics context, and in particular in this case with substituting a DC transformer as an equivalent circuit ...
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2answers
62 views
Calculate primary winding current in transformer under load[Exercise]
I have been trying to get to the answer to this exercise shown in the Solutions' reference page but despite countless attempts couldn't get to it.
it reads as follows:
...
-5
votes
1answer
45 views
why step up transformer is used at the generating station to step up the transmission line voltage?
how it helps by stepping up the generating voltage at the generating station to minimize the losses of a transmission line? when voltage increases current also increases. so it should increase the ...
2
votes
2answers
51 views
Meaning of infinite self inductance
I am reading about the characteristics of an ideal transformer and it is mentioned that self inductance of each coil is infinite. Could someone help me to understand the physics behind it? When self ...
0
votes
1answer
55 views
Transformer output connected to another transformer. Measuring 'Real Power' at input of first transformer
I have a watt meter connected to the primary of one transformer to measure power. The output of this transformer is connected to the input of another transformer.
The watt meter is measuring the ...
