Help me find cirquit, I forgot where I last saw it?

markusA · 22nd June 2011, 08:50 AM

I'm looking for a DC coupled cathode follower (I think it was a cathode follower?) with a servo on the cathode side fixing the output at dc ground.

I think I've seen it posted somewhere as cirquit of the week or something like it?

It's possible that it wasn't a cathode follower, my memory sometimes plays tricks on me. (I had a computer crash and all my bookmarks got lost.)
Any help is appreciated.

smoking-amp · 02:55 PM

Maybe something like this? The right side LTP (V3,V4) acts to boost the gm of the right side (V2)power triode. This was in the old anti-triode SET emulation threads. There was an RIAA phono stage circuit around too that used a gm booster, I think with just one add-on tube.

leadbelly · 22nd June 2011, 03:41 PM

Well DC coupling both the input AND output of a CF would be quite the trick now

Your idea that was a "circuit of the week" suggests the Tubecad site. I would just google "site:www.tubecad.com servo" and see what you find.

markusA · 22nd June 2011, 05:10 PM

Thanks for reminding me. I found a circuit of the month that's quite interesting.

Wavebourn · 22nd June 2011, 05:19 PM

Quote:

Originally Posted by leadbelly

Well DC coupling both the input AND output of a CF would be quite the trick now

It is easy, with 6N7 for example.

smoking-amp · 22nd June 2011, 05:20 PM

"I found a circuit of the month that's quite interesting."

Link?

markusA · 22nd June 2011, 05:22 PM

Circuit of the Month: October 1998

leadbelly · 22nd June 2011, 05:48 PM

Quote:

Originally Posted by Wavebourn

It is easy, with 6N7 for example.

I assume you mean it's easy using multiple sections, but only one of those sections is the actual CF.

Wavebourn · 22nd June 2011, 05:52 PM

Quote:

Originally Posted by leadbelly

I assume you mean it's easy using multiple sections, but only one of those sections is the actual CF.

No, I assume similarly to what was shown in Broskie's article, but no need for additional voltage drop resistor in cathode. Just a CCS in cathode with servo.

Even without CCS and servo (that is gyrator actually), load 6N7 on a choke with low DCR, that's it.

leadbelly · 22nd June 2011, 06:00 PM

Quote:

Originally Posted by Wavebourn

No, I assume similarly to what was shown in Broskie's article, but no need for additional voltage drop resistor in cathode. Just a CCS in cathode with servo.

If there's no resistor then what's setting the bias?

22nd June 2011, 08:50 AM	#1
markusA diyAudio Member Join Date: Dec 2009 Blog Entries: 8	Help me find cirquit, I forgot where I last saw it? I'm looking for a DC coupled cathode follower (I think it was a cathode follower?) with a servo on the cathode side fixing the output at dc ground. I think I've seen it posted somewhere as cirquit of the week or something like it? It's possible that it wasn't a cathode follower, my memory sometimes plays tricks on me. (I had a computer crash and all my bookmarks got lost.) Any help is appreciated.

22nd June 2011, 03:41 PM	#3
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Well DC coupling both the input AND output of a CF would be quite the trick now Your idea that was a "circuit of the week" suggests the Tubecad site. I would just google "site:www.tubecad.com servo" and see what you find. __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

22nd June 2011, 05:20 PM	#6
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	"I found a circuit of the month that's quite interesting." Link? __________________ Ohms Law V = I R

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22nd June 2011, 05:10 PM	#4
markusA diyAudio Member Join Date: Dec 2009 Blog Entries: 8	Thanks for reminding me. I found a circuit of the month that's quite interesting.

22nd June 2011, 05:22 PM	#7
markusA diyAudio Member Join Date: Dec 2009 Blog Entries: 8	Circuit of the Month: October 1998

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