What is my transformer output with no load? | Basic Electronics
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- Опубликовано: 18 июн 2024
- Have you ever wondered why the voltage of a transformer output with no load is higher than rated? Or maybe you've never noticed the relationship between the voltage level and the load. You're not alone. In this tutorial, we talk about transformers that are loaded versus open-circuited and why transformer secondary voltage can seem too high. The rated output or secondary voltage of a transformer is rated at a certain load and if you've got a different load, the output will be different. In our video about power supplies, we discuss about regulation and this is one of the reasons you need it. Check out the written tutorial on the CircuitBread website - www.circuitbread.com/tutorial...
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Table of Contents:
0:18 Setting up a practical example
0:49 The first reason why your output could be different than expected (different input than specified)
2:03 The second reason why your output could be different than expected (no load on the output)
2:49 Voltage regulation tolerances of transformers
3:12 Transformer outputs versus transformed, rectified, regulated, and smoothed outputs.
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Good to know! I'm actually about to try repairing a car battery charger, which has a very similar transformer in it! Should be interesting to see how it deals with the different amp settings/charge rates with this in mind.
Good luck and I'd be interested to hear how it goes!
Thanks! I may make a video if it ends up seeming worthy.
I'd be interested to hear what happened that bumped your views and subscribers up recently! Congrats, by the way; well deserved!
It was rather unexpected, actually - we got a brief but extremely large (for us) spike in views and subscribers when people found our PIC microcontroller series through "browse features" in RUclips. We're honestly not sure what that actually means. It's calmed down a lot but our overall daily views is still significantly higher than it was before that spike. It really motivated Sergey, though! We hadn't written done any new PIC tutorials for a couple months and then he cranked out four in about two weeks. Now I need to catch up and actually make them into videos...
@@nix324 Sry, but I like to "rock the boat" as much I dislike staying ignorant ;-). Of course, the material of the transformer's core, the thickness of wires and coils as well as the size of the core etc. have an impact on specifications. It's an evidence. But assuming these are "constant" from input to output (apart from the number of turns on each coil if we're not talking about Unity Transformers), then given a certain load and along those specifications, the ratios would represent a pretty good "first glance" assessment tool.
Thanks mate. I follow your videos, very useful.
Thanks for the feedback Nusret, we appreciate it!
I really like your approach for electronics. No bull..., no stupid jokes but science in practice and exactly how it is :) in real life
Thanks! We've been learning as we're going on and I'm trying to get more and more focused on the practical side of things with our tutorials. I appreciate the feedback!
For future - video discussing transformer efficiency versus frequency would be nice ;)
Ah, that's a good idea. I'd definitely have to look into that more, but maybe JB or one of the other engineers would have a better background on this.
How do you determine what a transformer output should be, if there are no specs on it?
If there's no specs or even part number to search for, then that's kinda weird. You can find the turns ratio just by giving it an AC input and finding the output but that's a bit sketchy. It would be a lot safer if you had a waveform generator of some sort so the amount of power you gave it would be quite limited and you could drop the voltage to something less dangerous. You won't know the max input voltage rating, you won't know what the output will be without full load (as you don't know what full load is) - I feel like if we had any lawyers they would tell me to say don't use it if you don't know what it's limits are. If you want to take the risks, I'd just look at transformers of a similar size and assume that your transformer will probably be in the same power range and don't push that limit.
@@CircuitBread Thanks for the reply. It's a small transformer in a pioneer home audio receiver. It has 120v primary and 9v secondary with no load, 4.8v with load. I don't know how common it is for when a transformer goes bad to either completely stop working or output an incorrect voltage. I googled all the number on it without success. I guess the only real way to determine what the output should be is to dismantle it and count the winding's per side, lol
Oh man, that would be an unbelievable pain in the butt! What makes you think that the transformer is bad?
@@CircuitBread The receiver wouldn't turn on, this is the first transformer in the system for "standby" power. It was also the only component that I couldn't read the specs on. The problem turned out to be a faulty ribbon cable, which is odd because there are no moving parts and it just randomly wouldn't turn on one day. Once it was working and went ahead and labeled all the transformers for future diagnosis.
Awesome that it was figured out! Ribbon cables are great but they're finicky. On two appliances I've dealt with in the last couple years, ribbon cable failure was the cause. I was able to fix one but the other, I couldn't solder it or find a suitable replacement. That was frustrating.
my amplifier when it idle it's worm and gets heat up like hell when on use. Is this normal for transformer?
Hi. It depends of power of your transformer.To overcome it, you should change more powerful one than actual one. But same voltage rate. (For ex. if your actual transformer is 24 V / 150W, you should change to 24V/ 250W ).
Yeah, I totally agree with Nusret. It makes sense that it gets hotter when there's a load and if it gets too hot, that means the power rating of your current transformer is too low.
@@CircuitBread thanks but I'm just worry about how much it's consuming power during idle to gen that much thermal
That's a valid concern. Ideally, the transformer wouldn't warm up at all if there is no load. So you can get a rough idea of the internal resistance of the transformer itself using an ohmmeter or multimeter, which should be very close to 0. Or you can check to see if there is a load on the output that you're not expecting. Those are the two most likely causes of unwanted power dissipation that I can think of.
Warm under load is ok. Hot is a bad sign and can damage the insulators on the windings.