Class D 200 Wrms with 2 mosfet cheap

[tullio1]

Hi Paskal what type of inductor have you used?

 

[stewin]

thanks paskal i will upload my photos too . is the amp still working and did you drive hard for a long time with 2 ohms did the outputs get hot or they were manageable?

 

[paskal]

Hi Paskal what type of inductor have you used?

i used a ferrite core, similar size to T106 iron toroid. you can refer to T106 toroid spec for the size.
at first i used 1mm gap but the amp went unstable during heavy load so i increased the gap to 3mm. probably the cores saturated. with 3 mm and suggestion from norazmi i increased the inductance to 33uh. tested 33uh and 44uh and both are stable with 3mm gap.

thanks paskal i will upload my photos too . is the amp still working and did you drive hard for a long time with 2 ohms did the outputs get hot or they were manageable?

yes, we tried lots of bass heavy scene and for prolonged period of time. i reckon around a couple of hours of test. the test are done in elevated level which i will never (ever) listen at my home. and we only tried specific scenes with lots of low frequency <20Hz.

and during the test there's no heat from any of the component. not from the output mosfet, not from the bd139/140 and the inductor is only warm to the touch. freaking awesome from such a simple and cheap design!

 

[tullio1]

Thanks Paskal for the information, could you post a photo of the inductor?

 

[stewin]

hi all has any one managed to make a higher voltage version of this amp ?

 

[stewin]

hi all i made bridged version and tested it but . when i pushed it hard with a 6ohm load that a 18inch woofer the amp failed after 2 minitues. . i think my tracks for pcb were small the ones feeding the output fets. also

>>> btw the circled components were heating above normal.

here are the photos

 

[szhighstar]

good to study, however toroidal core with gap is expensiver.

 

[stewin]

good to study, however toroidal core with gap is expensiver.

i have used 1mm gap by placing a piece of CD between cores

 

[szhighstar]

good technical, we also often open air gap for power core(Mn-Zn) for DC current requirement,howeve air gap dimension must be accurate.

 

[stewin]

good technical, we also often open air gap for power core(Mn-Zn) for DC current requirement,howeve air gap dimension must be accurate.

how do you manage to do that

 

[szhighstar]

we ask supplier of core to open air gap, because supplier of core is profession opening air gap, and can ensure AL value, we wind wire and make inductor, core is with air gap, so note the question when wind wire on core.

 

[jlester87]

Hi,

Is there a short circuit protect in this amp? Anyone tried it?

I have these ferrite toroid here, do I have to make a small gap or I'll just stack the two together to avoid heating? (like in the picture)

Thanks,

FT-87A Ferrite toroid

 

[paskal]

Hi,

Is there a short circuit protect in this amp? Anyone tried it?

I have these ferrite toroid here, do I have to make a small gap or I'll just stack the two together to avoid heating? (like in the picture)

Thanks,

FT-87A Ferrite toroid

are those really ferrite core? read from somewhere before that if it's ferrite than it doesn't really matter what type they are as long as they're ferrite. just make a gap in them to avoid saturation and measure the inductance. well that's what i read from a guide downloaded somewhere regarding the use of ferrite core for class d switching amp.

try and cut a gap into them with about 1mm of gap. if you can't get them to stabilize then try and increase the gap to 3mm. that's what i did to mine. they still saturate with 1mm gap. do remember that the inductance will change when you increase the gap.

as far as my experience goes with ferrite toroid, they're not really stable with fast frequency switching. mine doesn't. you're better off using a proper iron toroid for high switching.

 

[michelle]

hi Norazmi where you go no signs of you visiting the forums hope everythings OK
warm regards
michelle

 

[paskal]

hi Norazmi where you go no signs of you visiting the forums hope everythings OK
warm regards
michelle

norazmi is busy with work. he told me that he'll be back to the forum once he get everything sorted out at work.

 

[jlester87]

Do ferrite cores also attracted to magnets? because I tried placing magnet on my "green toroid" above and the magnet sticks to it.

 

[stewin]

hi guys this amp is amazing . but it failed after 20 mins pushing it hard with a kenwood 4 ohms 12inch subwoofer . the mid channel was o.k .

>>> the output fets i used were irf9530 and irf540 my voltage was +/- 35vlts dc

what can be the issue ? because in previous posts norazmi drove his amp with 2ohms for about a whole night.

 

[paskal]

Do ferrite cores also attracted to magnets? because I tried placing magnet on my "green toroid" above and the magnet sticks to it.

yes. my ferrite also attracted to magnet.

hi guys this amp is amazing . but it failed after 20 mins pushing it hard with a kenwood 4 ohms 12inch subwoofer . the mid channel was o.k .

>>> the output fets i used were irf9530 and irf540 my voltage was +/- 35vlts dc

what can be the issue ? because in previous posts norazmi drove his amp with 2ohms for about a whole night.

what type of inductor that you used? how much inductance? from my test the simple class d and tl074 non-ucd are not stable with low inductance. they tend to go unstable even with 20uH. better to have them running with above 30uh.

 

[stewin]

I used t-106 -26 from old pc power supply and used a hack saw to cut a 3mm gap .
turns was 18turns making it 20uh

 

[szhighstar]

if DC currents pass the inductor, advise to use powder iron or Sendust or MPP or high Flux core