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Old 25th October 2005, 02:24 AM   #1
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Default Introducing NEZ

Hi guys
this is NEZ , any suggestions on how it can be improved further
your input will be appreciated

cheers
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Old 25th October 2005, 06:07 AM   #2
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Hi Mastertech,

what means "NEZ" ?

First I see this topology in "elektrotechnik, oktober 1983" (Dr. Harms, University Hannover) used for a 25 VA poweramp for +/-350V outputvoltage.

It is a simple circuit to generate high voltages with a minimum of highvoltage n-transitors (or fets).

From there i tried it some years later (as a A/B-amp for +/- 500V) and i find it suffers at high frequencys on a strong asymmetry which stem from the capacitys of the bottom power/control-transistor/fet.

May be for a CLASS-A SPECIALIST and class-a biased and for smaller voltages it is useful!:

So its good to use high ft-devices.
You can supply the base of the top-darlington from a current-source or bootstrap it.

Because its a transconductance-amp you need strong feedback to get a lo-impedance output so i think you had to add a 2. gainstage. (i used a op-amp)

To hold the voltage before the outputcap stable you need from there also a dc-feedback-path.

Good luck.
Regards

Heinz!
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Old 25th October 2005, 06:10 AM   #3
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Quote:
Originally posted by powerbecker
what means "NEZ" ?
Not Exactly Zen?

Just a guess.

Oh! Duh. It's Zen spelled backward.

se
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Old 25th October 2005, 07:24 AM   #4
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Quote:
Originally posted by Steve Eddy


Not Exactly Zen?

Just a guess.

Oh! Duh. It's Zen spelled backward.

se

Ha, thank you!

I search for Zen and find it (NP)!

Indeed, the Zen looks very similar, but he has a CONSTANT-currentsource in the top, the Nez-top-currentsource is steering by the bottom-currentsource!

Regards
Heinz!
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Old 25th October 2005, 09:15 AM   #5
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Mr powerbecker

what an honor to have a German Engineer critisise my design
all your suggestions will be put to good use, your expertise
is second to none so is German Engineering

thank you sir
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Old 25th October 2005, 04:15 PM   #6
tlf9999 is offline tlf9999  United States
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Quote:
Originally posted by powerbecker
Indeed, the Zen looks very similar, but he has a CONSTANT-currentsource in the top, the Nez-top-currentsource is steering by the bottom-currentsource!

Regards
Heinz!

the top of the Nez is a constant current source, loading the bottom common emitter for gain.
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Old 25th October 2005, 04:30 PM   #7
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Hi George!

Funny circuit indeed!

Don't you want to connect your feedback resistor direct to Collector?
BTW, are those Darlington's in one package, if not you may want to add a resistor between base and emitter of output transistors, or so.

Cheers Michael
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Old 25th October 2005, 10:34 PM   #8
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Hi Mastertech,

thank for Your kind words too much honor!

Regards
Heinz!
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Old 25th October 2005, 10:54 PM   #9
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Quote:
Originally posted by tlf9999



the top of the Nez is a constant current source, loading the bottom common emitter for gain.

Hi tlf9999

this is true for Zen. Btw the bottom common emitter works also as a currentsource but not as a constant one.
The Nez consists of 2 currentsources like the Zen but in contrast to Zen none of them is constant. So you can get better efficiency.

Regards
Heinz!
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Old 26th October 2005, 02:09 AM   #10
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Hi guys wow the view count is heating up
micheal yes you could add resistors to darlington network if
the circuit is made up from regular transistors, thanks for
your kind suggestion, btw are you German Engineer we get
a lot of them in this thread thats why im asking

thank you all guys i plan to use all of your suggestions in future
versions of Nez

regards
George
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