Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on September 24, 2011, 02:07:30 pm

Title: A Long Tail Phase Inverter ???? ......... strange schematic ????
Post by: kagliostro on September 24, 2011, 02:07:30 pm

Which kind of PI is this ????

Kagliostro

Title: Re: A Long Tail Phare Inverter ???? ......... strange schematic ????
Post by: DummyLoad on September 24, 2011, 03:45:41 pm

Long tail with a current source. Each phase drives a cathode follower. Each cathode follower drives the grids of the output tubes.

--DL

Title: Re: A Long Tail Phare Inverter ???? ......... strange schematic ????
Post by: RicharD on September 24, 2011, 05:56:13 pm

I don't see any cathode followers. ????   :dontknow:

Title: Re: A Long Tail Phare Inverter ???? ......... strange schematic ????
Post by: DummyLoad on September 24, 2011, 06:32:23 pm

Quote from: RicharD on September 24, 2011, 05:56:13 pm

I don't see any cathode followers. ????   :dontknow:

you're right... haste post ry50 are the output tubes...the lines off the cathodes threw me. my apologies. notice that bipolar power supply is required. more of pain than it's worth.

i guess ry are cyrillic alphabet for GU in english alphabet?

--DL

Title: Re: A Long Tail Phare Inverter ???? ......... strange schematic ????
Post by: RicharD on September 24, 2011, 06:43:04 pm

I see the neg 120V but I also see that resistor connected to the positive lead of a filter cap.  That doesn't seem right to me.

Title: Re: A Long Tail Phare Inverter ???? ......... strange schematic ????
Post by: kagliostro on September 25, 2011, 07:03:09 am

I've find the origin of that schematic

this is the page (in russian - you must use google translator to try to understand something - russian to italian isn't good)

http://sergeev21.narod.ru/gu50pp.htm (http://sergeev21.narod.ru/gu50pp.htm)

the author say there is an NFB and also a positive current feedback in order to have a low output impedance

this schematic was after changed and not used

Kagliostro

Title: Re: A Long Tail Phase Inverter ???? ......... strange schematic ????
Post by: kagliostro on September 28, 2011, 05:15:37 pm

I think I've find the answer

wrong or not I think the intention for that circuit was a CCS for LTPI

http://www.freewebs.com/valvewizard/ccs.html (http://www.freewebs.com/valvewizard/ccs.html)

Kagliostro

Title: Re: A Long Tail Phase Inverter ???? ......... strange schematic ????
Post by: sluckey on September 28, 2011, 06:18:03 pm

Yep. Just like DummyLoad said in reply #1.

Title: Re: A Long Tail Phase Inverter ???? ......... strange schematic ????
Post by: kagliostro on September 29, 2011, 01:17:02 am

sometimes the truth is near but hides :icon_biggrin:

Kagliostro

Title: Re: A Long Tail Phase Inverter ???? ......... strange schematic ????
Post by: sluckey on September 29, 2011, 07:39:22 am

One mans 'sink' may be another mans 'source'.    :grin: