Class D 200 Wrms with 2 mosfet cheap

[stewin]

the artwork

 

[norazmi]

very nice and very compact Stewin . If u can change the driver transistor with BD139 & BD140 will be more better performance. and add rail filter caps with 1uf from VCC to GND, VEE to GND and VCC to VEE.

 

[stewin]

will change thanx

 

[renotrend]

here i can suggest for you, make sure driver transistor is BD139/140, i`ve seen that your R15 u have couple resistor there, what value they are? check it back, another symptom that might cause mosfet overheat is bad filter caps, change the 1uf filter caps at output. The core etd49 is overkill actually, lower your turn to 22-24 turn. then post your result here.

For testing, taking out filter caps and output inductor coild, dont connect any speaker, and turn your amp on see if u still have overheat at mosfet .

regards Azmi

Hi Norazmi
Sorry late to post ,little busy
I have found the problem my amp are ic socket and
Fet output p-ch is defect measure with multimeter is good
But in cuircuit is defect . Now my amp working normal ,good sound all of audio frekuensi

Btw i want make ucd discret 2 or 3 pair fet out put at 70 volt vcc .which one final schematic
Can u share

THANKYOU Norazmi

Regard,
Renotrend

 

[norazmi]

great to hear that. hmmm for discrete u can use Stewin schematic and hes already post at discrete thread. There is the final schema and u can use 2 pair is enough or if u want spare more $$ u can put 3 pair no problem, but totem pole need to be 2@3 pair per driver hi and lo side. back to the discrete thread so we can discuss there.

 

[norazmi]

sry double post. deleted.

 

[t68kv]

Here's mine:

@norazmi
Sir what do you think about the core that i have used? Its green/blue. Currently its working with 40mv offset.

 

[norazmi]

its iron powder from computer psu, its need to be cut with air gap about 2mm. and u need to add more turn for your winding.

 

[t68kv]

@norazmi

The current measurement of that is around 40uH using #20x2 wire.

BTW, i just want to know again the purpose of making air gap for this core. Thanks sir!

 

[norazmi]

okay, so 40uH u can stay with that value, i`m asking to make a gap because that core will be heat alot, or did u test it? Tell me about it

 

[t68kv]

220 resistors is hot in this configuration

 

[t68kv]

Cutted the core already but it seems no effect, i really need to find t106-2

 

[t68kv]

Hi sir norazmi,

I just want to know what other parts besides inductor, that may contribute on higher offset that maybe replaced with accurate ones. I also want to know how critical is 470nf polyester and 820pf mica plate. Its hard to find these locally and for know i only use ceramic 50v. Thanks

 

[norazmi]

when u cut the core, can u touch it? its hot or not? offset 40mv is no problem, what is your supply voltage? 820pf 50v is ok no problem with that. u can lower the inductor up to 24uH and filter cap i already mention about it please read at previous page.

 

[t68kv]

I used smaller green/blue core cutted and wind single #20 wire, metey says its around 35uH. Now BD is only warm mosfet is dead cool "maybe because of heatsink also", DC offset is -40mv. Coil is hot but can retain touching it up to 5 seconds. The only problem are the resistor "220 ohms", hot. I also noticed that the two 2.2K 1W resistor are hot. Thanks

 

[norazmi]

2.2k 1w is hot its normal no problem with that. please post bottom picture of ur amp. what is your supply voltage?

 

[t68kv]

Ok I'll post it later. Im using CT 30VAC.

 

[stewin]

hi norazmi i have finished the board i posted on #141 . it is clear but the outputs get hot i am using +/-28vlts how can i reduce the heat in the outputs .

 

[stewin]

the schema . the rest are in post #141

 

[norazmi]

Stewin output transistor should not hot . check if u use bad output mosfet OR bad output coil winding OR bad output filter caps OR check any driver transistor to mosfet maybe defect. The problem will come alots if ur using recycle component when they r not working properly. I`ve face many diyers problem comes from recycle component, Notice that i`m always using BD139 and BD140 for mosfet driver.