N-Channel mosfet amplifier schematic needed

[rajeev luthra]

Thanks Lars,
I will try this new version of the Zeta shortly
Rajeev

[SuperAudioBuff]

Hi Lars:

I posted a message not long ago, what about the 1000W version, have we abandoned this? Or will this be back around? I'm still very interested!

[bubu]

Quote from www.oliveaudio.com

This version only has one set of output devices for simplicity. But it will still produce up to 320W RMS in 4 Ohms with the proposed output devices. For higher power, the output devices and bypassing 63V caps can be replaced, and the module can then produce up to 1000 Watts RMS!

Man, hope this helps as an answer to your question. Regards,
Valentin

[keypunch]

Originally posted by bubu
Quote from www.oliveaudio.com

Man, hope this helps as an answer to your question. Regards,
Valentin

A few questions for my own education if I may?

I am correct the context of the changing of the 63V bypassing caps was with respect to the larger +-V supply rails, wher ethe working voltage of the bypass cap would be raised to a value reasonability larger than the +-V supply rails one wanted to use?

Of more interest to me how the actual capacitance value of the bypass caps for the output devices. I am not questiong the design value chosen, just the how it is determined. I have seen different N-Channel designs that will use 330uF, 100uF, et al for the bypass caps, and in some cases paralleled with a non-polar cap. The prior version of the Zeta used 47uF as the bypass caps, and some designs use a set of bypass caps at each end of the output device rail. All I am asking is hwta factors, design considerations and formulas are used to determine what the values should be or suggest the ball park value. Part of the reasoning for these questions is in case I find it useful to "tune" or experiment with values if an amp will be dedicated to a frequency band aka active crossover based system.

As a side question seeeing as the output devices are connected to the +-V rail which has large filter caps, why are these caps on the output device rails needed? Sorry for the question, but I am trying to understand the why. I am not questioning estabilshed design practices, just trying to exapnd my understanding.


Regards,

John L. Males
Willowdale, Ontario
Canada
30 November 2005 02:43

[Workhorse]

Originally posted by keypunch



As a side question seeeing as the output devices are connected to the +-V rail which has large filter caps, why are these caps on the output device rails needed? Sorry for the question, but I am trying to understand the why. I am not questioning estabilshed design practices, just trying to exapnd my understanding.


Regards,

John L. Males
Willowdale, Ontario
Canada
30 November 2005 02:43

Hi John L. Males,

The Bypass Caps are used to BYPASS the Noise, arised from the spray of harmonics into the power supply when large currents are being conducted through output devices.....Thus these helps in Bypassing the Noise to the Ground...

regards,
K a n w a r

[Workhorse]

Originally posted by Lars Clausen
Rejeev: The NPN transistor is working like a simple VBE multiplier, and creates an offset of the gate voltage, allowing for a smaller rail loss on the - rail.

Any small signal darligton can be used.

Best regards

Lars C

Hi Lars,
Though you have overcome the rail loss at -Ve rail...But what about the Rail Loss at + Rails...or is it that you have symmetrified the rail loss of negative rail in comparision to the existing rail loss of positive rail......
Why haven't you Tried to split the Driver [Rail to Gate resistors] resistors in 2 equal value, than bootstrapped them with the Caps From their midpoint to the output node.....Giving you Rail to Rail swing in both polarities.......

regards,
K a n w a r

[SuperAudioBuff]

Lars:

I guess I'd like to hear from you most. I see the new 320W version of the Zeta, and you say it's as simple as adding new bypass caps w/ raised voltage and adding output devices, does the old 1000 w design work that was posted a while ago, or how should we approach this?

Please could you post a separate schematic for 1000W version, and has anyone tested this yet?

Anyone know any proven designs for MOSFET 1000W or so power levels w/ DIY schematics available?

[Peter M.]

Lars,
Sounds like a very interesting project. I need a subwoofer amp and I`ve got a bunch of IRF150N`s, two 2x38V 800VA toroids and lots of aluminium. I also have 20 mallory caps 23000uf, but they are only rated for 50V, is series connecting a bad idea?
It would be nice to see your Zeta schematic, but I can`t find it on your website, I can only see the front page. When I click "read more" the front page just shows up again...maybe its just me... (and the schematic links in this thread doesn`t work)

Best regards,
Peter

[bubu]

Cheers from Romania.
Valentin

[Lars Clausen]

Merry Christmas

Valentin: BTW incredible christmas decoration you have in Bucharest this year!!! I have never seen anything like this before!

Peter: Here is the Schematics of ZETA320:

www.oliveaudio.com/nch2.gif

(Hope this helps!) The ZETA is a low cost alternative with a lot of muscle. Of course not 'high end' but then the price of building it is incredibly low. So for a subwoofer can be the perfect amplifier.