Misunderstand of sijosae schematic

crashman · 5th May 2010, 08:56 AM

Why need 2 LM317 to operate one filament?

urgent!

SY · 5th May 2010, 09:55 AM

Schematic?

Arnulf · 5th May 2010, 10:16 AM

Quote:

Originally Posted by crashman

Why need 2 LM317 to operate one filament?

urgent!

Because the author drew his schematic this way ? Each regulator delivers cca. 145 mA, tube requires 300 mA to operate. Perhaps he wanted to spread the heat around ... who knows. With decent heatsink you can easily use just one LM317 (and change value of 20R and 15R resistors, of course, to get parallel resistance of cca. 4.16R).

Yvesm · 5th May 2010, 12:49 PM

My first impression was "will never flight" !
But, at a second look it seems to me that each LM317 is used as pull down for the IRF610 source followers.
Don't be confused by the "+Bat-1" and "+Bat-2" labels which are indeed the anode connections to each active load (2SK30) wich each drive an IRF610.
If so, each source follower draw near 150 mA.

My two pence.

Yves.

crashman · 5th May 2010, 12:55 PM

Thanks for the input guys, but the measurement between filament and the ground is more than 20 volts.

crashman · 5th May 2010, 12:58 PM

thanks guys , but the measurement between the filament to the ground is more than 20 volt. do you guys get this value?

Arnulf · 5th May 2010, 02:15 PM

Put tube into socket and the readings will go down to 6.3V.

Measuring open CCS will give, well, what any self-respecting CCS should give into infinite impedance - infinite voltage, supply permitting

kevinkr · 5th May 2010, 04:44 PM

It appears that those ccs both control the current through the output devices on each channel and each one also provides half the filament power. (current sources sum directly [Norton]) It is actually rather clever and obviates the need for a separate filament supply and also reduces the dissipation across each LM317 as the voltage across them is reduced by the amount of the filament voltage.

This works well because the swings required at the output are small as compared to the available supply voltage, the ability to swing in the negative direction is compromised by the voltage drop of the filament.

Yvesm · 5th May 2010, 04:52 PM

So, you confirm my guesses

crashman · 5th May 2010, 10:21 PM

I have a new problem. the LM317 is hotter than the other one. lol

5th May 2010, 09:55 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Schematic? __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

5th May 2010, 02:15 PM	#7
Arnulf diyAudio Member Join Date: Feb 2009	Put tube into socket and the readings will go down to 6.3V. Measuring open CCS will give, well, what any self-respecting CCS should give into infinite impedance - infinite voltage, supply permitting __________________ mod verb, transitive /mod/ to state that one is utterly clueless about the operation of device to be "modded" and into "fixing" things that are not broken; "My new amplifier sounds great so I want to mod it."

5th May 2010, 04:44 PM	#8
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	It appears that those ccs both control the current through the output devices on each channel and each one also provides half the filament power. (current sources sum directly [Norton]) It is actually rather clever and obviates the need for a separate filament supply and also reduces the dissipation across each LM317 as the voltage across them is reduced by the amount of the filament voltage. This works well because the swings required at the output are small as compared to the available supply voltage, the ability to swing in the negative direction is compromised by the voltage drop of the filament. __________________ www.kta-hifi.net

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5th May 2010, 12:49 PM	#4
Yvesm diyAudio Member Join Date: Jul 2004 Location: Ardeche	My first impression was "will never flight" ! But, at a second look it seems to me that each LM317 is used as pull down for the IRF610 source followers. Don't be confused by the "+Bat-1" and "+Bat-2" labels which are indeed the anode connections to each active load (2SK30) wich each drive an IRF610. If so, each source follower draw near 150 mA. My two pence. Yves.

5th May 2010, 12:55 PM	#5
crashman diyAudio Member Join Date: May 2010	Thanks for the input guys, but the measurement between filament and the ground is more than 20 volts.

5th May 2010, 12:58 PM	#6
crashman diyAudio Member Join Date: May 2010	thanks guys , but the measurement between the filament to the ground is more than 20 volt. do you guys get this value?

5th May 2010, 04:52 PM	#9
Yvesm diyAudio Member Join Date: Jul 2004 Location: Ardeche	So, you confirm my guesses

5th May 2010, 10:21 PM	#10
crashman diyAudio Member Join Date: May 2010	I have a new problem. the LM317 is hotter than the other one. lol

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