150W MOSFET Amplifier with IRFP250x2

[lycanlk]

NX14

Can I drive NX14 with 2 pairs of IRF640 without any changes to the amp?

regards,
Lycanlk

 

[apexaudio]

Can I drive NX14 with 2 pairs of IRF640 without any changes to the amp?

regards,
Lycanlk

Yes you can,
Regards

 

[lycanlk]

Thank you!

Thanks for the last reply.

Did you miss the post #160?
or you don't have the pcb for this amp?

regards,
Lycanlk

 

[apexaudio]

Thanks for the last reply.

Did you miss the post #160?
or you don't have the pcb for this amp?

regards,
Lycanlk

I lost files for this amp.
Regards

 

[lycanlk]

I lost files for this amp.
Regards

That's alright! You have given us more than enough. Anyway it looks like a pretty simple amp.

Regards,
Lycanlk

 

[lycanlk]

NX14 T0-220

Dear Mile,

I designed a board for me to drive NX14 with T0-220 type outputs. There can be mistakes which I have done with tracks. Could you check them for me please? (I'm not good at designing)

Thank you!

 

[lycanlk]

Found some mistakes..

and corrected...

 

[lycanlk]

my NX14 with IRF640

Amp works. But I need to know how to bias this amp proparly.
Already burnt a couple of outputs.
run it with +/-30 supply

regards

 

[AndrewT]

2pair of 640 on +-30Vdc using 0r15 as Rs should be OK.
Try 25mA (4mVrs), 50mA (8mVrs), 75mA of bias (12mVrs)
Monitor temperatures as well as bias, for long enough to ensure you are seeing typical fully warmed up operating conditions.

 

[lycanlk]

2pair of 640 on +-30Vdc using 0r15 as Rs should be OK.
Try 25mA (4mVrs), 50mA (8mVrs), 75mA of bias (12mVrs)
Monitor temperatures as well as bias, for long enough to ensure you are seeing typical fully warmed up operating conditions.

Thanks Mr. AndrewT.
I know you are a genius in calculations
Can I calculate the bias current by measuring the voltage across 10R/5w resisters at each rails ? If so what should be the voltage in each case?

Regards

 

[AndrewT]

I have posted repeatedly that inserting supply rail resistors is a bad way to try to set up output bias.

 

[kml88]

PCB N10 please....

 

[kml88]

Mr.Mile, if i use 4x2irfp250n, what must be changed?

 

[lycanlk]

Bridge mode

Supply +/-35v
Removed 100n between signal ground and power ground and connected.
Used external inverted/non-inverted input for bridging.
Bias current 25mA
Insufficient current in my power supply to drive both amps. Used it just for testing.

Thumbs up for the amp!
Cheers!

 

[kidrockx]

Dear Mile,

I designed a board for me to drive NX14 with T0-220 type outputs. There can be mistakes which I have done with tracks. Could you check them for me please? (I'm not good at designing)

Thank you!

Hi lycanlk,
Can you share this pcb? i have some FQA70N10 , can i use it for NX14?
Thanks

 

[Maroof]

Hi apex,
I have made 2 NX14 pcb for stereo amplifier . I want to know that if PSU-5 can supply current for both channels or I have to make 2 PSU-5 circuits ,1 for each channel? And what should be VA rating of transformer if I use 50-0-50 vac? One transformer for both channels.

 

[apexaudio]

Hi apex,
I have made 2 NX14 pcb for stereo amplifier . I want to know that if PSU-5 can supply current for both channels or I have to make 2 PSU-5 circuits ,1 for each channel? And what should be VA rating of transformer if I use 50-0-50 vac? One transformer for both channels.

PSU5 can supply both channels with 300VA transformer.

 

[Maroof]

PSU5 can supply both channels with 300VA transformer.

Thanks

 

[Maroof]

PSU5 can supply both channels with 300VA transformer.

Can I use 4ohm speakers with 300va transformer?

 

[apexaudio]

Can I use 4ohm speakers with 300va transformer?

Yes, 300VA is ok