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Old 15th September 2011, 06:15 PM   #151
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Hi Gregg,--

Yes, I was thinking on the likes of --Oleg's circuit, --about halfway down the page. Just something nice and simple but effective....

They seem to call these circuits 'electronic-chokes'--But, They aint IMO, a 'Ripple-Filter' would prob be a better description....

A Choke has the ability to store a relatively large amount of energy, while the ripple-filter has no energy storage capacity of itself at all, relying on the preceding caps to supply the energy--Not that it matters, with what we are doing here....

I believe a couple of caps, say, an eletrolytic of say, 470uF and a nice film of 50uF should work well on its output. The Film cap could be mounted physically close to the output stage....
--Probably the electrolytic aint needed seeing the ripple-filter will be effectively removing all the crap from the PSU anyway, but thats just me....
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Old 15th September 2011, 06:48 PM   #152
M Gregg is offline M Gregg  United Kingdom
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Hi Alastair,

Yes Oleg's circuit looks interesting. Are you going to give it a try?

I have ordered the IRF710 fets.
I have also fitted a NTC CL60 inrush suppressor for the Tx's

I will also fit the neon protection for the DC coupled stage.(grid cathode)

Managed to find some 4.7M resistors 2W 1.kv flash over.

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M. Gregg
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Old 15th September 2011, 08:47 PM   #153
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
I believe a couple of caps, say, an eletrolytic of say, 470uF and a nice film of 50uF should work well on its output. The Film cap could be mounted physically close to the output stage....
--Probably the electrolytic aint needed seeing the ripple-filter will be effectively removing all the crap from the PSU anyway, but thats just me....
I would think that their is enough "C" in the PSU so just a film cap after the (ripple filter) should be OK. Only thing is you need a minus supply version for the other leg..?

It would be interesting to see how low the value of C-filter-C could be in this circuit and still keep ripple down?

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M. Gregg
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Old 15th September 2011, 09:18 PM   #154
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Well you could prob calc. it out with the aid of PSUD....

The level of ripple the ripple-filter will tolerate would depend on the voltage drop (Headroom) you set the active device to....
--What nasty effects could occur with a high ripple from smaller caps, and insufficient headroom on the ripple-filter, I cant imagine....
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Old 15th September 2011, 10:23 PM   #155
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
--What nasty effects could occur with a high ripple from smaller caps, and insufficient headroom on the ripple-filter, I cant imagine....
I can HuMMMMMMMMMMMMMMMMMMMM let me Think...LOL


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M. Gregg
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Old 15th September 2011, 11:03 PM   #156
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Aye, probably, But it wouldnt be the usual ripple/ramp hum we are used to...

I'm thinking a sorta flat-topped triangle wave...

Description sounds ugly, so guess the noise would be too!
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Old 17th September 2011, 05:52 PM   #157
M Gregg is offline M Gregg  United Kingdom
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Relay input board connected.
Just for interest.
Cables
PTFE cable silverplated.
Jupiter silk/silver. << built into a screened cable.
Only because its a short run.




Regards
M. Gregg
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Old 20th September 2011, 11:30 AM   #158
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Wow! Thats coming along really nicely!

You should have it working soon! Looking forward to your results!
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Old 20th September 2011, 02:26 PM   #159
gkn202 is offline gkn202  Luxembourg
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Originally Posted by Matthewong View Post
Hi, would like to ask whether the vacuum tube OTL power amp worth to build? How is the sound performance if compare to normal output transformer type?? Does anyone has any good schematic diagram for OTL power amp, can share out, thinking to try to make one.
Hi dear, I just finished a layout for a Totem-Pole OTL with very low Harmonic Distortion levels (0.079% at 20 W rms, 8 Ohm and 1Khz). The design has not been tested in a practical implementation. It is symmetrical and uses that many 6C33C tube stages that you can afford (or have the power supply for).

I've opened a Thread on this this morning, and hope receiving comments and suggestions for further improvements.

Attached you'll find a ZIP with the LTSpice model and the library.

CU Gary
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Old 20th September 2011, 02:38 PM   #160
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Quote:
Originally Posted by gkn202 View Post
Hi dear, I just finished a layout for a Totem-Pole OTL with very low Harmonic Distortion levels (0.079% at 20 W rms, 8 Ohm and 1Khz). The design has not been tested in a practical implementation. It is symmetrical and uses that many 6C33C tube stages that you can afford (or have the power supply for).

I've opened a Thread on this this morning, and hope receiving comments and suggestions for further improvements.

Attached you'll find a ZIP with the LTSpice model and the library.

CU Gary
Hmm....

That aint much use --Without a Schematic!

All I get is a page of meanigless numbers and another page asking what program it needs to open it!

At least mine WORKS in the real world, with real tubes! Ive never put much faith in simulations, Especially with Tube circuits, Sims never seem to hold up!

Any chance of a scheme we can look at??
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