♫♪ My little cheap Circlophone© ♫♪

Mr Elvee,

I would request you to please reply to my following academic question.

Will there be any benefit of combining input and feedback ground together and floating it through a resistor of typically 10R resistor from the power ground?. The question is possible elimination of Earth Loop if any. The present build has already very very low 50 Hz Hum with input short almost dead silent. Will this arrangement reduce 50 Hz hum further?. I have not yet practically tested it. I need your expert advice on this issue as you have not done this in your original schematic at Post # 1.

The snapshot of modification is attached.

Elektor Elektronics in its "Mini Cresendo" Amplifier has done this in past.

Thanks
Rajesh Katiyar
 

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Dear Mr Elvee,

Though the reply does not necessarily pertain to me yet I want to correct you for your comments "customer". In my openion no one is your customer all are your followers. You have given your Circlophone design absolutely free to all boarders with out taking any royalty at all. Also you were kind enough and ready all the time to answer and resolve to the querries of all boarders.

I too have discarded all of my previous made chip and discrete amplifiers as they do not stand before the performance of Circlophone.

I dont know why I prefer MOSFET version over BJT version may be because of its simplicity. The performance appear to be the same. I have decided to make another HEXFET Circlophone with 50-0-50 rail voltage using Bootstrap circuit suggested by you with IRFP240 OP devices in days to come. I have started procuring components for the same.

Thanks
 
Hi Junm,
i jump in to answer :).
You can compare the schematic to the original one.
Mostly parts are same.

Mine is not fully build now on revisited board. :(
Feel free to use if you like.
Regards.
 

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Hi terranigma, do you have the base schematic of this hexfet board?

I suggest you to follow Bangla H's version since it is available as gerber by Bangla H. Drilling alone is a most sensible reason for ordering PCB's instead making own.

Hi Junm,
i jump in to answer :).
You can compare the schematic to the original one.
Mostly parts are same.

Mine is not fully build now on revisited board. :(
Feel free to use if you like.
Regards.

Thank you for fast response. That would be not easy for me to find the actual post which includes original PDF files. As I mentioned at up, ordering PCB's makes more sense if a gerber version is available.

If you follow the thread recently, can you add the bootstrap circuit as an option? It makes the rail-to-rail swing is attainable on MOS version.

Thanks.
 

Junm

Member
2008-12-23 5:52 am
Dau
Hi Junm,
i jump in to answer :).
You can compare the schematic to the original one.
Mostly parts are same.

Mine is not fully build now on revisited board. :(
Feel free to use if you like.
Regards.
Hi Bangla, big thanks for your help, i have boards of this one but cant find the base schematics, i want to try this since i have several hexfets and vertical fets. I also have Laterals k134, k 1058 but i think it will not suitable maybe due to low Vgs . but a little adjustment on bias component will do,

@Elvee , what components to be adjusted in order that this will work with laterals except for the pin connections?