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-   -   L7 MOSFET AMP (http://www.diyaudio.com/forums/vendors-bazaar/202923-l7-mosfet-amp.html)

ljm_ljm 21st December 2011 01:14 PM

L7 MOSFET AMP
 
1 Attachment(s)
I designed a small power amplifier。
It uses a pair of VISHAY IRFP240 IRFP9240。
It uses the CFP input, and the suspension of the output, similar to LME49830 structure.
It works in very stable.
In the +-56V voltage.it is can out 150W 8R。
PCB board area 63*78MM only

astankov 21st December 2011 05:25 PM

Any chance for schematic now?
It is pointless to make such threads without schematics and only one or two pictures. If this is a commercial product and you don't want to share it only to show the beautiful PCB (actually is very beautiful!) there is a thread for pictures and it will be better to post more of them.
I'm very curious about the schematic because I'm IRF lover so if there is any chance to see it will be very happy.

Best regards!

ljm_ljm 22nd December 2011 02:14 PM

Do not worry.

This circuit can be a good power play IRF FET.

I can briefly explain.

It uses the CFP transistor input stage. Single-ended voltage amplification.

Internal structure similar LME49830, suspension of driving.

It can work very high frequency, and waveform perfect.

I tested with the 2700K HZ.

Does not appear as an ordinary FET amplifier instability phenomenon.

ljm_ljm 22nd December 2011 02:20 PM

I will try to design better quality amplifier, and they are very cheap.

I would like to include not only an actual amplifier circuit, but also includes parts of the performance and parameters. I think this is a whole.

Will be used only truly understand.

ljm_ljm 1st January 2012 12:49 PM

2 Attachment(s)
Please refer to the circuit.

CBS240 1st January 2012 01:04 PM

Hi

I see I'm not the only one that uses totem pole BJT driver stage for each output FET gate. I do prefer the totem pole driving stage always stays well within class A. Using simple diode bias may cause one of the devices to leave class A during very fast transient output current signals, also it requires thermal feedback to the diodes because without the degeneration of an emitter resistor, thermal runaway can destroy a small signal device in a few blinks of the eye.:xeye: I use 3 diodes and an emitter resistor on the inside BJT to set bias above the largest charge current needed to operate the FET. Many semi-fab companies make triple diodes in a 6 pin SMD package.;)

katiyar 1st January 2012 01:06 PM

Please post schematic and pcb layout as many diy enthusiasts will like to build the same. Extremely professional pcb does not look diy product.

ljm_ljm 1st January 2012 02:32 PM

Quote:

Originally Posted by CBS240 (Post 2842100)
Hi

I see I'm not the only one that uses totem pole BJT driver stage for each output FET gate. I do prefer the totem pole driving stage always stays well within class A. Using simple diode bias may cause one of the devices to leave class A during very fast transient output current signals, also it requires thermal feedback to the diodes because without the degeneration of an emitter resistor, thermal runaway can destroy a small signal device in a few blinks of the eye.:xeye: I use 3 diodes and an emitter resistor on the inside BJT to set bias above the largest charge current needed to operate the FET. Many semi-fab companies make triple diodes in a 6 pin SMD package.;)

I am using IRF610 as the bias voltage provided. And with the output stage FET to maintain the same temperature.

ljm_ljm 1st January 2012 02:33 PM

Quote:

Originally Posted by katiyar (Post 2842102)
Please post schematic and pcb layout as many diy enthusiasts will like to build the same. Extremely professional pcb does not look diy product.

If you have a L7. You will find the above parameters in detail. L7 is a very simple DIY AMP.

CBS240 2nd January 2012 12:38 PM

Quote:

Originally Posted by ljm_ljm (Post 2842151)
I am using IRF610 as the bias voltage provided. And with the output stage FET to maintain the same temperature.

Hi
My comments is in reference to the TO-92 driver stage(s), the undegenerated comp class A BJTs that are detached from the diodes that bias them, not the Vgs multiplier bias control for the FETs.


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