# transformer

1. ### Mutual inductance and coupling coefficient

Hi, Does anyone here knows how to measure the mutual inductance and coupling coefficient for small values inductors? I have succeeded to do that for one common mode choke using an LCR meter, where the L1 and L2 where 4mh, for another choke (where L1 and L2 are 1mH) i have got a coupling...
2. ### Why does a transformer transfer power from the primary to the secondary one?

I'm struggling to keep my mind wrapped around the function of the transformer and, in the process, regretting the days I snooze back in my Electromagnetics class as an EE student when I was a boy:) I'm searching for an abstract explanation, but not just an equivalent one. I want it to be rooted...
3. ### Need help with a ccfl inverter

I recently got a little casio portable tv, but the lcd controller was fried. I noticed however that the backlight still worked, so I took it apart and found that it was a flourescent backlight. I wanted to use the inverter transformer for some cool projects, however I couldn't find out which...
4. ### Mutual Inductance Measurements and Calculation

I am trying to compare the analytical and experimental results of coupling factor and mutual inductance. I can measure L, Q, Rs, and measure total inductance by connecting the two windings in series and getting the highest value to calculate mutual inductance (M) as indicated here...
5. ### distortion in ac output from transformer

Hi guys, I want to know, why I am getting a distorted output from a step-down transformer? Why is it not a proper sine wave? Is it normal? What may be the problems? Does adding a 100uF capacitor solve this problem?
6. ### Effect of change in frequency or duty % on transformer output

In case of a smps transformer of 1:2 primary and secondary turn ratio roughly the output voltage will be double & current will be half of input. My questions are what effect will be on output, if 1) Frequency increase or decrease (when duty % is constant) 2) duty % increase or...
7. ### Output current from MOSFETS (bridge) before trafo?

I having a concern about the what kind of current that I have after the MOSFETs (in the transistor bridge) before transformer. Before the MOSFETS I have a DC current from an AC/DC converter stage. So I am a bit confused if the current before the transformer is average, peak-to-peak or RMS...
8. ### What is wrong with my transformer output?

The thing is, I was trying to regulate a 220V-9V to 5 volt. I did it though. Everything was right.I was trying to make a dark sensor with NOT gate () The settings are good. But it wasn't working fine with the AC to DC adapter.( It is working fine with a battery like the video). The thing is...
9. ### How to set up my 220V to 9Vx2 transformer?(What is wrong?)

So I tried to make an adaptor that can give me voltage around 9-10 Volts. There are total 5 wires as you can see in the attached image. I am using a 1000 uF(25V) capacitor parallely after the bridge diodes as said. But the capacitor is heating up and I think the lid/head of the capacitor is...
10. ### Safe voltages and transformer secondary

I read many times, form many sources, that 60 VDC or 30 VAC are potentionally dangerous. I know that it is current what matters, but higher voltages lead to greater currents (assuming same resistance, of course). I also know that primary and secondary windings of a transformer are dangerous. But...
11. ### Piezoelectric Transducer with Arduino

I want to drive piezoelectric transducer with resonant frequency 110khz and input voltage 70 volts ac with arduino. I generated a square wave of same frequency with arduino than converted it into ac voltage using RC filter than for the step up I used transformer small getting amplitude of 67...
12. ### Lamp step-down transformer is not working. How to repair it?

I found a lamp at home which is not working. I have used the multimeter to detect where the problem was coming from and it seems that the problem is coming from the transformer. It's a 220 to 12 volts transformer and I can read 220 in the input, but nothing in the output. So, something is not...
13. ### Using a 12 Volt Regulated Power Supply as a Battery Charger - Questions

Hi folks I found this forum via a Google (is your friend0 search. I found some threads loosely related to my question, but nothing specific. Hopefully, some of you electrical/electronic aficionados may be able to assist. I have an old 'Transwest' brand Regulated Power Supply in good condition...
14. ### 60Hz transformer and Lichtenberg figures (fractal burning)

Background: A friend is looking to do some fractal burning (google it) (edit: also called Lichtenberg figure) and has salvaged a microwave oven transformer (MOT) for this purpose. However he likes to think big and isn't satisfied with the 2kV output so has asked me to look at increasing it. As...
15. ### How to modify a toroidal transformer windings?

I have a toroidal transformer which has one input of 220 Volts AC, and 2 secondary outputs of 40 volts AC each one. I want to modify it to have two 220 volts outputs instead the two 40 volts outputs that it has at the moment. I would assume that it's a very easy task and I have just to modify...
16. ### I made a plasma speaker with an arduino and a flyback transformer today

Here's a video of it in operation. I'm pretty happy with how it turned out :)
17. ### Would a high voltage low current generator be more efficient?

Generators have to deal with counter torque. The more electrical load placed on the generator, the greater the counter torque. Since the counter torque is a function of load current, if one designed a generator to be low current/high voltage, and in conjunction used a transformer to then convert...
18. ### Transformer Theory

Good Day, I need help understanding transformer operation, I have been working on a Microwave Oven Transformer conversion commonly found on YouTube and the likes where the secondary coil is replaced with 2 turns of thick gauge wire (50/75mm^2). The idea is that voltage is stepped down and...
19. ### Help with a schematic

Hi, This is the schematic of a ccfl driver I "reverse engineered" by looking at the board. I am pretty sure the schematic is correct. J2 represents the primary of the transformer. Can anybody help me figure out which pins of the primary correspond to which winding? Thanks
20. ### re-purposing yellow "site" transformers

May not mean anything to non-uk people! So anyway, looking through eBay listings I keep seeing site transformers (if you don't know, they are used on building sites etc to provide 110v cte power for tools), sometimes very cheap, and keep wondering how easy or hard it would be to take one apart...
21. ### Why Microwave oven transformer is welded?

As I know transformer laminations should be insulated to minimize eddy current. If so, why microwave oven transformer E I cores are welded together!
22. ### Will one of these new ZVS heating coil drivers drive a flyback transformer to generate HV

http://www.aliexpress.com/item/5v-12v-ZVS-Induction-Heating-Power-Supply-Tesla-Driver-Board-Module-Coil-New/32619428560.html I know roughly how they work, and i also know that ZVS type circuits exist for flyback transformer drivers, the kind that use TV transformers to generate high voltage, i...
23. ### Repairing a BWD 521 cathode ray Oscilloscope - no traces, hissing noise

Hi all. I recently purchased a (obviously) second hand CRO oscilloscope. It worked fine for a couple of days, I was just getting used to it. Then one day, I left it on for 10 mins or so with both traces active on screen. A while later, I heard this high frequency hiss, so I switched it off. The...
24. ### 220v to 12 V for a big load winch

Hi everybody, I am not only new here but have little to no clue about electrics/electronics, but a question, where I am hoping to get some ideas/answers. I have purchased a winch enabling me to pull our boat on a trailer in and out of the water on a ramp. The winch requires 12V and I would like...
25. ### 48 Volt Phantom Power Supply with Photo-Schematic. Transformer Question.

Hey guys, This is my first post and I am happy to have found this website. I am currently working on a project using a PCB and jumper wires to make a 48v Phantom Power supply to be used with multiple condenser microphones. To make a long story short, I found a "mostly" detailed post on another...

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