Making car amplifier SMPS with tl494 + DC Protection

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weird noise from transformer

Hi!


I'm making a battery powered powersupply, wich makes 2x50V, at about 6-700W. For testing, I'm loading the power supply with 2 amplifiers, and drive them with music.
When I turn the volume to higher levels, then strange sounds are coming from the transformer (ETD44). I recorded the sound with a webcam's microphone:
http://sziget.mine.nu/~danko/aramkor/trafo_1.mp3
http://sziget.mine.nu/~danko/aramkor/trafo_2.mp3
Unfortunatelly the computer picks up a lot of noise, even when the 12V powered supply is turned off. So please ignore that noise, which is on the records...

I don't think, that the feedback is oscillating, becouse that rasping voice is not a "discrete" frequenzy. I have looked on the powersupply's output with my scope, I haven't seen any signs of oscillation.
After that, I thought, maybe the "E" cores aren't clamped perfectly. So I changed the "clamping" to a harder one, but that weird noise was the same...
Maybe, the core is saturating? I dont think... Becouse then my mosfets would blow up :) There is a current limit in this SMPS, but that's only an "overload limit", not a cycle-by-cycle type current limit.

Have anyone experienced like this?

P.S.: I can post pictures of the board, and schematic, if it's needed
 
Here's the schematic of the "controller" section. It's a little bit messy....
 

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Here's the power-section, and a picture of the panel.

http://sziget.mine.nu/~danko/aramkor/car-smps/dscn0431.jpg
On the left side, there are the mosfet driver ICs.
On the right side there's a 8pin IC socket. That WAS the controlling part some time ago. That's not used, I use instead of that the TL494, on a small board.
 

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Hi! There are "solderable" wires, wich means, that you can remove the lacquer by heating the wire with your soldering iron. Unfortunatelly my wire isn't this type. I have to use a hungarian conservating stuff. Transating that material to english, it's called "salycic". I hope you know what i'm talking about :)

I pour some salycic on the table, put inside it the wire, and I heat them with my soldering iron. The salycic melts, and it gets off the lacquer from the copper. It is VERY smelly! When I soldered those wires I put about 20 wires into the salycic simultaneusly.
 
transformer Kit

zagisrule! said:
Glad to hear it 2pist :)

I was thinking today about offering a kit including all parts (PCB, MOSFET's, transformer, IC, misc components) for a SMPS. It would be easier for many here to make their GC car amps when all they have to do is assemble a kit and be guranteed a working design.

Would anyone be interested in something like that?






-Matt


Yes I would be interested in one kit like that ;D
 
tico70 said:
himanshuraval,

Just a question, are you using a heatsink for the mosfets?

I am using the following circuit and it work perfectly. I am still working with two types of cores (toroid and ETD39)...for now the toroid is performing better and much easier to wind..

An externally hosted image should be here but it was not working when we last tested it.


Do you have pcb for this?
 
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