How Autotransformers(Variacs) Work
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- Опубликовано: 4 окт 2024
- How Autotransformer Variacs work, as well as a demonstration.
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Very clear video. It's interesting how you limit the current using 3 microwave oven capacitors. I have a few of these but they all seem to run hot. I will try this to gain more control and reduce the tempco. Thanks.
Excellent video. You are a good teacher!
+Jerry Zakariasen
Thanks Jerry! Be sure to check out my other videos, share with others, and rate thumbs up.
Hey that was an excellent presentation thanks for sharing with us
Glad you enjoyed it Mike! Be sure to look over my extensive video playlists below for many other videos of interest to you, subscribe, and most importantly take one minute to share a link to my channel with others on social networking sites. Thanks
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Thanks, easy explanation.
You're welcome Ethan! Be sure to look over my extensive video playlists below for many other videos of interest to you, and most importantly take one minute to share a link to my channel with others. Thanks
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Very Cool - every other 'explanation' I have seen are more about how to use - or how it 'works' like explaining how an amp works, by teaching how to plug it in and connect speakers! BTW I have one, Griffin and George 0-30v AC/DC with full bridge (1970's) - but I cannot see how they scrubbed the (UK) remaining 200 odd volts! Would like to raise the sweep to 0-40 - is that possible?
Nice explanation
Thanks for liking the video!
Nice and clear informative information thank you
Glad you enjoyed the video Dan! I have many great videos on my channel covering many different subjects, so be sure to look over my video playlists for other videos of interest to you and most importantly share.
شكرا جزيلا
Very food explanation
Glad you enjoyed the video!
Nice 👍👍👍💪tks
You're welcome! Thanks for watching
this is a great vid thank you so much for it
i have a question
which is more efficient normal transformers or a variacs ?
because i'm thinking of making my own transformer
but this type sounds easier to make for higher amp rating
Probably a normal transformer.
So you're saying that if you take a microwave oven transformer and hook it up to a power supply without a secondary winding it will pull more amps and overheat??
nice video
Thank you Wasim! I have many videos on my channel that cover a wide range of subjects, so be sure to look over my video playlists below for other videos of interest to you, and most importantly share.
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Interesting how you have a MOT minus the hv coil
That toroid of which you speak, is that just a steel circle? Also, when making a winding like what you have in that transformer, do the individual copper wires need to not be in contact with each other, hence the enamel coating, or do they all touch with an enamel overlay on the whole system? One more question if you don't mind, are the winding wrapped in one layer or are they in multiple layers around the toroid? Thanks for your time, I'm off to subscribe now! This channel looks awesome! My brother is an electronics tech by trade and things like this give me something to talk to him about.
Hello. No, usually not laminated steel. Usually ferrite, or powdered iron. Does not matter if the enamel wire touches. You want a neatly wound transformer. One or more layers.
Great video, can you create an isolation transformer and a variac in one unit?
Two 120 volt M.O.T. primary colis back to back. ( 120 volts in 120 volts out isolated) , and tap as needed for various voltages. M.O.T.s should give high current.?
You will get good current output. 8 to 10 amps! Just make sure you place the cooling fan close to the transformer to keep it cool. MOT's were designed to be driven higher than they should to save money and weight.
electronicsNmore is it possible for you to describe that a little better I'm lost that you just said MOTS were designed to be driven higher to save money and weight? A MOT is already heavy so how can they be saving on weight? Is that why I've started to see that they have started to use aluminum windings on the primary?
Ben Boudreau
The size of the MOT would normally be LARGER to deliver the same power output.
Did you have to put those three caps in series just because you didn't have a 33 uF cap available?
I was demonstrating with what I had on hand. If you have a 33uF on hand, you'd use that. Thanks for watching!
To make this safer to use, can we use another M,O.T. to make an isolated 120 volt supply before tapping these voltages? That would isolate the taqpped voltage from the mains. Please show on a video. Thanks.
They usually only use one winding, but you can take 2 identical MOT's and place both primary windings into one core and weld it back together. Now you are isolated from the AC line. Tap the secondary 120V output. Be sure to use the microwave oven cooling fan on the transformer core.
That may be safer for someone new to working with line voltages, thanks for keeping practical electronics alive..
electronicsNmore why do you say be sure to use the fan? Do the windings get hot if you're not pulling power through the secondary? If you put two 120 V windings on the same core like you said.
The transformer must be cooled if used more than a few minutes at a time, unless you rewind the transformer.
electronicsNmore does it depend on the transformer and how it was made because I've run one with a rewound secondary and it doesn't get hot and I've had it running for more than five minutes maybe even 10 minutes.
Sir. could one remove all the MOT windings and shunts, and completely rewind it using Silvio Klaic's transformer calculator for the purpose of using it as a high amp variable bench power supply? Or are these transformers too crude for this application?
Walt
Walter Cengia Hello Walt. Yes. Please refer to my other video below.
ruclips.net/video/3uCuA032lYw/видео.html
enlightening... thx
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did this transformer works for solenoid type inspite torroid
Put bridge rectifier and make a battery charger which can be regulated and automatic.Thanx
You can do that. :-)
Since Not a are getting harder to find. I've found a new source in HID lighting the 500 and 400 MH shop or warehouse lighting burns our thhe high start caps and most business just toss them in the trash . There is a massive transformer in these . I was able to find 20 just at 1 warehouse
Thank u very much.. For this..
You're welcome! Be sure to rate thumbs up and share. Thanks
electronicsNmore okk sir
thank you...
So basically an auto Transformer is the same as a model train control Transformer?
Hi George. If it operates the same way as the variac in my other video below, where a toroid is being tapped at different areas, then yes. Thanks for watching!
ruclips.net/video/oI-md8dRAbo/видео.html
@@electronicsNmore more or less but the brush moves across the flat side of a square transformer rather than toroid. You should check out the rodin coil sometime or Poe coil as well!
You've described where to touch in the total winding to obtain lower or higher voltages, but have made no mention of what is happening electro-magnetically !
Because it was very simple. More turns of wire within a magnetic field = higher voltage, less turns, lower voltage. The taps are doing that.
what is the difference between the potentiometer and auto transformer
One is a variable resistor, and the other is used to transform power.
awesom
can i ask you if how much is the rating of capacitor i will put if i have a variac of 15kva.
You need to play around with the values. You can also look online for "capacitive Reactance" calculators. Thanks for watching!
make a clipping detector for car audio plllllzzzzzzzz
Make a starship coil auto transformer
That's one unusual coil. :-) Thanks for watching Dave!
@@electronicsNmore when using magnetic viewing film on it, it shows the Flux lines don't go around the outside , it keeps them in a vertical column
why use transformers over auto transformers?
Why? Because you can have a wide range of voltage outputs using only one winding.
In other words it is a big version of a potentiometer.
Here it is called variable resistor, over there it is called potentiometer and over the other place it is called variac. Isn't that nice.
What about heat. oh my heat and better not touch anything or else.
I think that might be wrong. I'm trying to understand how a variac works, and I think that what's happening is that the iron core around which the wire is wrapped is becoming magnetized. The AC current between the hot lead and the wiper is driving the magnetism in the whole core. Therefore, the part of the wire between the wiper and the neutral lead becomes energized just as if it were a separate winding in a two-winding transformer. If I'm right, then in effect the power is regulated almost opposite to what happens in a rheostat, which uses resistance to lower the voltage. Please understand that I'm struggling to understand how this works, so it's probable that I have gotten this wrong.
What you're calling a "toroid" is actually a torus. When you add winding conductors about a torus, then, it becomes a toroid.