Making car amplifier SMPS with tl494 + DC Protection

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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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.
 
hey luka it finaly worked! ! !
i think the problem was putting load on one side!
i tried to load it with two 24V car bulb and worked fine!
now i'm going to test it with more load.

do you have a good x-over schematic?

best regards and thanks

delta-delta
 
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