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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Determining VA rating of the small transformers

I have a 1000VA toroid transformer which weighs 8 Kg. Based on this power-to-weight ratio, can I conclude that another transformer which is EI cored and weighs 7 Kg must be 875VA? Or such ratiometrics ...
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36 views

How to build 5W LED bulb circuit from 230V 50Hz main AC supply with and without Transformers? [on hold]

Please answer with circuit diagram with all values or give me the link.Tell me the efficiency also. Thank u...
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2answers
32 views

Does the transformer in this circuit cause a voltage drop to the DC motor?

In this circuit: Is the transformer and the circuit on the secondary side of the transformer only there for the test-point or does it affect the voltage to the DC motor? The DC motor is a 90V motor ...
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1answer
62 views

Can I use a 12v battery to power a class 2 transformer (120v input 15v output )? [on hold]

I'm attempting to use old computer speakers ( Altec Lansing) and make a mobile speaker system,but I'm unsure if I can connect the transformer that came with it to power it using a 12 v ( small, like ...
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1answer
79 views

Will the use of an isolation transformer improve the safety of my power supply?

I have a power supply design that makes use of a half-wave rectifier and a non-isolated buck Swtich Mode Power Supply IC to step down 120V 60Hz AC power to 12V DC. I then use a Linear Voltage ...
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2answers
54 views

Simple and cheap overload protection for multiple secondary taps of a transformer

I have got an old transformer with multiple secondary taps with the ratings shown in the following figure: I plan to put the transformer in a suitable case and connect the secondary taps to binding ...
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1answer
54 views

custom transformer winding

I want to create a step-down transformer from 230V to 115V. This will give us 2:1 turns ratio. So this means 2 turns in primary for every 1 turn in secondary should work. But if the 230 Vac supply ...
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0answers
38 views

Using 1:1 Transformer for High Side Switching

I'm working on a 2-sw Forward Converter with isolated input and output. The design is complete on paper, but I still have a problem in my head: High side switching. The question is, can I drive the ...
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1answer
37 views

Using two isolated secondaries of different voltages to power one device

I'm making a simple 555 timer circuit to drive a flyback transformer. The 555 circuit controls an N-Channel mosfet which is what drives the flyback. I have an old receiver mains transformer that I ...
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2answers
51 views

Reasonable maximum exciting current 60Hz step up transformer

What should be a resonable exciting current for a 720VA 60Hz transformer? Primary 12V/60A and secondary 110V. I'm measuring about 2A (around 3% of maximum rated current) in the primary while the ...
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2answers
78 views

What happens to a normal transformer when the frequency is increased and the sine wave is changed to rectangle?

What happens if I grab a 220 sine wave 60 Hz transformer with an output of 12v if i feed it with a 220v square wave? And what happens if I increase the frequency? Like 100 Hz? And if I grab the ...
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1answer
38 views

Convert 220V AC to give out TWO 12V DC 3 amps [closed]

I need an output of two 12 v dc 3amps , how can do it with a single transformer ? Well i am sorry for i framed the question badly! I have an appliance that need needs 12v 2amp for one component (...
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1answer
39 views

Transformer efficiency

An ideal transformer should have insignificant power loss, meaning, input VI equals to the output VI. Question... To achieve this is it true the transformer must have equal copper volume in its ...
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1answer
112 views

Help understanding a 30 year old schematic for a contact aligner

I got this old contact aligner I want to fix up but it is missing the control box, this is the diagram which is from like 30 years ago. Any suggestions on how to interpret this? J2 and J3 are the main ...
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1answer
46 views

A question on an approximate calculation of an ideal transformer inductance

I have a 230V to 6V step-down transformer. I'm trying to calculate the inductance of the primary side 'roughly' in an easy way. Here is what I have in my mind: For that I added some illustrations ...
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1answer
34 views

How ignition coil in automobile works..?? what are the winding count for ignition coil..?

I just want to make ignition coil on my own. can you please help to done primary and secondary winding for same..? 40KV output required from 12v input supply.
3
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2answers
50 views

Dab vs Dac transformer

simulate this circuit – Schematic created using CircuitLab Why might one use a delta-wye transformer with the delta configured in Dab rather than Dac, or vise versa? Will this cause a ...
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1answer
57 views

24V AC converter to 12V DC at 1.2A

I am facing annoying troubles converting 24V AC to 12 V DC. The goal is to supply 1.2A current to 12V DC load. I am both limited in input power (I can only use 24V AC output of a transformer that can ...
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2answers
64 views

What is difference between 2 transformers rated to give output the same voltage but different current (ampere)?

What is difference between 2 transformers rated to give output the same voltage but different current (ampere)? Such as, if a stepdown transformer is rated as 12V 600mA, and another is rated as 12V ...
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1answer
63 views

Trying to understand the working principle of a weird transformer driver / oscillator

I'm trying to fix the high-voltage power supply of an old scope. The HV transformer is burnt, and I'm trying to replace it with a similar one (EPC19 core), but I'm failing. I already know how to wind ...
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1answer
103 views

why would one use a current transformer with both live and neutral lines?

Could one use this to measure the phase difference if one had the voltage measurement? I have looked at the below household power meter, and was baffled by (what seems to be) the current transformer ...
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1answer
60 views

A-C delta-wye phase shift

simulate this circuit – Schematic created using CircuitLab My question is, because the delta primary in this case is connected A-C, rather than A-B, does this effect the direction of the 30 ...
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1answer
44 views

multi-tap transformer relay for LM317 tips

Example circuit: Since LM317 is a linear regulator it will get very hot when i try to draw around 1 amp @1.25v with a 24v input. The transformer i have at home have these taps: 24v 12v 5v Is it ...
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1answer
39 views

Transformer Problem Diagnosis

I have a suspected bad transformer in a board that has come out of a treadmill which I'm trying to use for another project. I suspect the transformer as I have removed all connectors and replaced one ...
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0answers
59 views

Start a dead battery car with a power/USB charger [migrated]

today my car couldn't start beacuse of dead battery. The battery is not old, I simply left my dash cam attached for a few days without using the car... I'm alone at home and my car is in a difficult ...
3
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3answers
349 views

Transformer: Double primary winding?

I found the picture below on the Internet about a double primary winding transformer. I understand how a simple primary double secondary winding transformer works, but I don't see the point in making ...
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4answers
98 views

Television flyback transformer: does it do 2 tasks ie. horizontal flyback and E.H.T.?

Television EHT transformer is also called Flyback-transformer? E.H.T. (Extra High Tension) generates the cathode ray; ie. acts in same direction of the main pathway of running electrons, i.e. "...
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1answer
44 views

Transformer secondary wired to primary and secondary of second transformer

simulate this circuit – Schematic created using CircuitLab I see something like this for ethernet, and it confuses me. What is it for? What does it do? Could I remove that from the schematic?
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1answer
57 views

75kva three phase 208v delta to three phase 208v y transformer wiring/results?

I recently purchased a used 75kva 208v delta to 208v Y transformer and have some concerns about some strange results. We would like to use this transformer to create separate (isolated) service ...
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2answers
65 views

Oil Transformer

I'm trying to understand how transformers work so I understand the primary/secondary stepping down/up voltage or current but why do they use oil (in oil tank) with transformers?
4
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1answer
64 views

Delta-Wye transformer neutral

This is my first post and I am happy I stumbled across this forum. I am preparing for a job interview and have been given a Delta-wye transformer schematic and have been asked to discuss the phase ...
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2answers
42 views

Transformer Question - Two Output of Different Voltage

I'm fairly new to electronics, but still have a basic understanding (1st year Electrical Engineering Student). I've started a project of repurposing a used treadmill I found online for $20 as a ...
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1answer
38 views

Will using an SSR on the secondary side of a transformer lead to heating due to harmonics?

I have a resistive heater with a resistance of 18 Ohms. The heater is mounted on a job which has a thermocouple mounted on it. I need to use a SSR based controller to control the temperature measured ...
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2answers
67 views

Transformer with hysteresis in LTspice

I would like to model a transformer in LTspice with hysteresis and saturation (or just hysteresis would be nice). I have already tried the Chen model which I don't like and tried to model a regular ...
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1answer
364 views

What do you call a 1:3 turn ratio transformer?

I need a small surface mount or slightly larger transformer with a 1:3 turn ratio that will triple my voltage from 3.3 to 9.9 volts. I have been literally searching the internet for such a thing and ...
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0answers
23 views

Power Supply MultiChannel Floating

I have been looking into DC power supplies and can't seem to find how to do multi-channel floating +/-. Correct me if I am wrong but you can isolate two channels by having a center tap on a ...
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2answers
175 views

How does television EHT Transformer (that connected to anode) operates in DC?

A step-up transformer takes AC input and gives AC output. Then, how does the E.H.T (Extra high-tension transformer) create 18 KiloVolt or more, DC-output on the CRT (enough to shot the electrons on ...
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0answers
28 views

RC network in 12v 50watt halogen desklamp

I'm trying to repair a halogen desklamp that has a transformer based on this circuit: R is a 0.5 ohm 1watt resistor for the main RC network that was blown, I've got some replacements ordered on the ...
3
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1answer
134 views

Decoding Transformer circuit for power supply generation

I am referring below schematic of transformer to generate power supplies in the system. Transformer used is step up transformer (Input-5V, Output: +/- 12V, +/- 48) But I am not getting how ...
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3answers
84 views

What are all the reasons that transformers are considered safer? [duplicate]

I am making a circuit for measuring AC mains voltage and current and I want to avoid using a transformer because it introduces distortions. But everyone says that the circuit will be considered unsafe ...
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2answers
75 views

Induced EMF in a transformer

In a transformer a sinusoidally varying voltage is applied to the primary coil of the transformer which give rise to a time varying flux which induce another sinusoidally varying EMF in the primary ...
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2answers
70 views

What physical construction features in a transformer control the dot polarity?

As we know, the dot convention is used on transformer symbols to denote whether the transformer "inverts" the signal passing through it or not. However, I am not clear on what in the physical ...
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2answers
85 views

Toroidal Core Calculation

Few days ago I got sample of toroidal core from my friend. I don't know any technical details of core just know OD-10cm, ID-6cm, height- 5cm and wet about 1.845 kg(M4 grade CRGO). I want to make ...
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1answer
46 views

Why can I power a 9 volt application on the Collector side of a transistor, and not the Emitter if Base gets 5 volts.

I have a 9 volt application that I want to trigger using an Arduino and an NPN transistor. The Arduino can supply 5 volts to the base. I tried to place the application on the Emitter side of the ...
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1answer
66 views

120v power supply section 220v adaptation

I'm building a very simple tube overdrive, power supply section of the schematic can be seen above. as you can see the circuit has been designed for 120v. I will be dealing with 220v instead of 120v, ...
1
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1answer
50 views

Understanding transformer datasheet

Preamble I need an small isolation transformer for 0-6V 400Hz AC (this is my external signal, amplitude is the value): I should get <10mA load from the primary signal source, and in the same ...
2
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1answer
48 views

Is this pulse transformer in saturation?

I have the following schematic: RB3 is connected to PIC microcontroller digital output. I am wondering is it possible to know from the output voltage waveform is this pulse transformer in ...
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2answers
100 views

When to “wind-your-own” vs “scavenge” a transformer?

I often see answers for one-off designs including the advice, "Just wind a transformer...." Like it's no big deal. Did I miss a class in which they handed out a sheet listing the formulas for core ...
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1answer
65 views

Connecting Transformer to Ethernet PHY

I have Ethernet PHY from Marvell (88E1111-B2-BAB1I000) and Ethernet transformer (S558-5999-AT-F). By mistake the MDI P&N connection got interchanged on the transformer side. Will it work?
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2answers
33 views

Relay sequencing: Inhibit state change of one relay if the other is on

I'm trying to find a way to have one relay lock its state if the other is on. Example, 2 relays total: If relay 1 is on then relay 2 can't change state, either turn on or off. Meaning if relay 2 is ...