2000W Power Supply for my car audio.

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2000W at 12V is 167A:smash:

For car audio, you'll want something more around 13 - 14 volts.

The going standard here is 13.8V, due to the normal float voltage of lead acid batteries in many situations.

At 13.8V, 145A gives 2kW, however, you're going to want a supply capable of something more like 160A in that case just so you're not pushing its limits.

Then again, how often will you use the entire 2000W?
This is a really big supply relative to most stuff people 'build' as projects.

As a linear supply, this is simple, but requires a lot of BIG parts. Big rectifiers, big transformer, big caps, failsafes of sorts.

As a SMPS power supply, this is tricky for the DIY person as when anything goes wrong, it blows up rather catastrophically due to the high-power nature of the circuit.
You could rewind two microwave oven transformer with 13 volt secondary. Wire the primary's in series for 240v, run em in parallel for 120v.

I doubt you will quite get 2000 watts but it will be close. Big car amps actual power ratings are almost always a few times what they actually are anyways. If you don't have three alternators on your car, your amp is not drawing 2000 watts.
If you re-wind microwave transformers, you must remove the shunts from the core unless you want a current-limited output.

These appear as bars of core material in the window of the transformer between the primary and secondary windings and shunt a magnetic path from the inner leg to the outer legs, causing saturation at a certain point and allowing current regulation so that the magnetron doesn't just draw limitless current.

MOTs are very useful for home-brew transformers, both current limited and not.

engzonta said:
Thanks for all. I need a project of a power supply with output voltage around 13.8Vcc, but I will not use in parallel with the car battery. I will only use the supply. For this, the supply does not need to be float.

Why not a truck battery with a floating charger?

After all, these amps were designed to run from a battery and the battery is capable of supplying the current.
Yes, microwave oven transformers are excellent for these projects for a few important reasons. One is that the secondary ratio between voltage and turns is almost 1. This means it's easy to arrive at the desired voltage with an estimation and a little tweaking. For 12 or 13 V, it's dead easy because you only have that many turns going on. The ratio is not perfectly 1, but it is close and has dependency on power voltage.

Another nice thing about MOTs is that they are big. They are useful up in the 500 to 1000W area.

There are multiple ways to deal with them. The most elegant is to remove the "I" section of the core and slide the windings off(if you get the shims out of your way). Removing the "I" requires breaking the weld or cutting it, which isn't always possible.

If you can't remove that piece, you have to destroy the secondary winding to remove it. When I was about 10 I used to do this a lot for making my own trafos. I would use a hacksaw to cut the secondary into two pieces and pry them off separately. Winding a new secondary in the window is not as easy as doing it on a bobbin to slide on the core with the "I" removed. But it is possible.

And remember to remove those shunts unless you want a current-limited transformer!
I am planning on turning an MOT into a field magnet for Nuclear Magnetic Resonance projects.

I will try and remember to take photos of how I would turn it into a homebrew transformer before I turn it into a field magnet.

There are simple ways of testing to see if it's working. Plugging it into 120Vac is one, except this leaves you with the dangerous voltage of the secondary and enough current to easily be lethal.

If I wanted to test an existing one just to see if it worked more or less, i would supply it with low voltage AC, like for example 12Vac from another transformer. This way the voltage you measure on the secondary will only be about 130V. This is still a lot, but nowhere near as dangerous as the 1400V or so you would otherwise get.

It's very rare for one of these to die. The most common cause being a short in the windings I would imagine. Or perhaps a short from the secondary to the core due to arcing. I've current not seen a toasted one and I've been through hundreds and hundreds.

I've seen every other part of the microwave oven toasted more or less, hehe.
Electrone said:
Just a note on numerical notation. 2.000 means 2 accurate to three decimal places.

Someone wouldn't want to write to his buddy to say that a certain RF transmitter is rated 2.000 watts of output when it really puts out 2,000 watts.
Yes, some posters are lousy at sticking to conventions.
The problem is that conventions vary between countries.
Maybe we need a Wiki explaining how to post numerals, multipliers, etc, on this Forum.
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