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Old 28th October 2009, 12:14 PM   #21
Ejam is offline Ejam  Australia
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Default Power Supply

Nelson

Because I'm injecting power supply noise through the bootstrap resistor to the input signal?
Any suggestions to alleviate this aside from the "very quiet power supply", perhaps forgetting about bootstrapping.....

On the left mosfet I have the drain and source lettering around the wrong way, sorry about that.

Regards

Ejam
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Old 28th October 2009, 02:49 PM   #22
mos57 is offline mos57  Italy
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Quote:
Originally Posted by Ejam View Post
Francesco

If you look back at John Broskie's Tubecad musings he came up with an "inverted circlotron" circuit back in June 1999 where the output was taken from the drains giving both voltage and current gain. Anyway, thanks for the pdf, will get busy with my Italian.

Mike

Sounds good, when can we get a look at the details?

Ejam
Is the attached figure that you report?

Also if the load is connect from the drain sides, it isn't consequential to have voltage amplification.

Then, where are connected the input signals? I not view.

This is most relevant in this circuit to have gain voltage.

However, in this figure, if you look at the amplitudes of the input and output signal you can see that they are the same, so John not meant to show voltage amplification, i think.

Francesco
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Old 28th October 2009, 03:32 PM   #23
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Quote:
Originally Posted by Ejam View Post
Because I'm injecting power supply noise through the bootstrap resistor to the input signal?
No, the input is referenced to Ground, but the gain of
each Mosfet is referenced between the input and the +
rail of each device. Any noise in the supply will be amplified.

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Old 29th October 2009, 12:18 AM   #24
Ejam is offline Ejam  Australia
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Francesco

These are John's claims not mine, suggest you take it up with him.

Ejam
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Old 29th October 2009, 12:22 AM   #25
Ejam is offline Ejam  Australia
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Default Noise

Nelson can it be cancelled by feedback between the drain and the gate?
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Old 29th October 2009, 02:28 AM   #26
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You need to avoid creating the problem - it is easier than
fixing it with feedback.

Look at an F5 for an example, where the input to the Mosfet
Gate is taken from the high output impedance of the Drain
of an input JFET so that you have some power supply
rejection.

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Old 29th October 2009, 09:02 AM   #27
Ejam is offline Ejam  Australia
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Nelson

OK so now its two stages instead of one, and around we go again. There is nothing like being poorly rejected by your power supply to dent your budding zen designer fantasies. See what Mark comes up with. To Zen or not to Zen that is the Pass enigma.

Francesco

By the way Francesco, cool amp, learnt a little about design and Italian along the way, hence it is the journey etc. etc. Is it possible to do away with the jfet stage, as I thought you said your amp was single stage only, not two. Probably not, same problem with power supply noise.
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Old 29th October 2009, 12:30 PM   #28
mos57 is offline mos57  Italy
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Quote:
Originally Posted by kevinkr View Post
One of the very interesting claims in this patent relates to the fact that the output is ground referenced and from a dc standpoint there is no (dc) voltage present at the load. This is a big difference from the floating tube circlotrons I've worked on (and designed) in the past. (My last design had ground referenced outputs, but it was not the case that the outputs were exactly at ground potential - they could float some volts above or below but were common mode in theory at least.)

The topology also seems to allow for very convenient differential drive ground referenced from a balanced source or even a center tapped IT transformer.

Wonder how well it works. Built a working prototype? Pretty cool idea.
Thanks much for your appraisal.
Another great its advantage is in my mind, that people can drive this circuit with one unbalanced signal. How many people have balanced source in their set stereo?

Circlotron need 2 balanced input, so at the end it's necessary another phase splitter stage. How is good? how many is balanced and symmetrical? How to realize it? How other many parts need?
I think this last is very delicate on the final result over the same power stage.
At least with my referred circuit one people can save one stage.

Now about my patent.

People must understand that when look my circuit they not think as simply circuit stage, but as a "whole power amplifier".

0ne guy can put a source signal from his CD player or tape in the input amplifier and wired its output to the speaker.

Francesco.
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Old 29th October 2009, 03:44 PM   #29
mos57 is offline mos57  Italy
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Quote:
Originally Posted by Ejam View Post
Nelson

OK so now its two stages instead of one, and around we go again. There is nothing like being poorly rejected by your power supply to dent your budding zen designer fantasies. See what Mark comes up with. To Zen or not to Zen that is the Pass enigma.

Francesco

By the way Francesco, cool amp, learnt a little about design and Italian along the way, hence it is the journey etc. etc. Is it possible to do away with the jfet stage, as I thought you said your amp was single stage only, not two. Probably not, same problem with power supply noise.
Since the two bank of power supply are applied in opposite phase to the circuit (output terminal), also the power noise is in opposition, so you must match these last to cancel or lower the noise at the output.

Its not enough to put caps of equal value (their tolerances are high generally), but you must make a real measure of the two noise side.

Regards, Francesco.

Last edited by mos57; 29th October 2009 at 03:58 PM.
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Old 29th October 2009, 04:33 PM   #30
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Quote:
Originally Posted by Ejam View Post
OK so now its two stages instead of one, and around we go again. There is nothing like being poorly rejected by your power supply to dent your budding zen designer fantasies. See what Mark comes up with. To Zen or not to Zen that is the Pass enigma.
Take a look at ZV5, which has the same situation on the
noise because the topology has many similairities.

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