Using PSU Designer to calculate DC filament supply

porkchop61 · 25th October 2005, 01:09 PM

I'm trying to use the PSUD2 to design a DC filament supply for 2 6SN7 tubes.
I assume you use a resistive load because its a heater, but where do I find the value of the resistance? I also assume that this resistance changes as the tube heats up.
I've never used DC for heaters, so I thought I'd give it a try.
Are the heaters still wired in parallel as AC heaters are?
Thanks in advance.
Glenn

Robert McLean · 25th October 2005, 01:50 PM

Use a resistive load of 6.3 V / .6 A = 10.5 ohms. This is the hot value, valid after 15 or 20 seconds. Yes the initial value is lower, and your simulation for the first 15 seconds will be inaccurate, but so what ? I think you are really only interested in the steady state DC voltage and ripple.

As for series or parallel, that depends on wether you have 12.6 volts ( use series ) or 6.3 volts ( use parallel ) available.

porkchop61 · 25th October 2005, 04:27 PM

Thank you Robert

I have 6.3 volts, so I'll be using that.
Glenn

porkchop61 · 25th October 2005, 04:33 PM

Is the 0.6A is for 2 tubes in parallel?

Yvesm · 25th October 2005, 04:49 PM

Try to set heathers in serie: less current, easier to filter, smaller caps, lower current peaks

a win win approach !

Yves.

porkchop61 · 25th October 2005, 05:05 PM

Using the series approach, if one tube heater fails the whole heater circuit fails, correct? I'm not sure this is a good or bad thing. I guess you can't use the circuit either way (series or parallel). The only hard part would be troubleshooting which tube failed.
Glenn

dhaen · 25th October 2005, 06:28 PM

You don't need to know the resistance if you use the constant current load option in PSUD2.

Series or individual is much safer than parallel, because of the potential voltage rise when one valve is removed.

Why do you need DC? It can be noisier than AC!

astouffer · 25th October 2005, 06:42 PM

How can DC be noiser than AC?

dhaen · 25th October 2005, 06:51 PM

Quote:

Originally posted by astouffer
How can DC be noiser than AC?

Diode noise. Hum is easily managed by twisted wiring and centre-tapped (or resistively divided) windings, referenced to ground. Indirectly heated filaments were created for this very purpose.

porkchop61 · 25th October 2005, 08:01 PM

Yes, I've never had a need for DC heaters in the past, but I like to have a "plan B" if needed. It's also another thing I'd like to experiment with just because I've never done it.
This is for a line level 2 tube 6SN7 preamp, so the wiring is pretty simple compared to other jobs I've done.

I never thought about the voltage rise if a tube is removed, good point. Of course I would never do such a thing

Here's my layout so far:

6SN7 preamp

Glenn

25th October 2005, 01:09 PM	#1
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Using PSU Designer to calculate DC filament supply I'm trying to use the PSUD2 to design a DC filament supply for 2 6SN7 tubes. I assume you use a resistive load because its a heater, but where do I find the value of the resistance? I also assume that this resistance changes as the tube heats up. I've never used DC for heaters, so I thought I'd give it a try. Are the heaters still wired in parallel as AC heaters are? Thanks in advance. Glenn

25th October 2005, 01:50 PM	#2
Robert McLean diyAudio Member Join Date: May 2005 Location: Stittsville, Ontario, Canada	load resistance for PSU designer Use a resistive load of 6.3 V / .6 A = 10.5 ohms. This is the hot value, valid after 15 or 20 seconds. Yes the initial value is lower, and your simulation for the first 15 seconds will be inaccurate, but so what ? I think you are really only interested in the steady state DC voltage and ripple. As for series or parallel, that depends on wether you have 12.6 volts ( use series ) or 6.3 volts ( use parallel ) available. __________________ Robert McLean

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
K-502 Filament supply (or K-12M)	jmillerdoc	Tubes / Valves	6	18th November 2009 12:59 AM
Yet another DHT filament supply	astouffer	Tubes / Valves	25	5th July 2009 11:08 PM
Modelling a DC filament supply in PSU Designer II	G	Tubes / Valves	3	7th February 2008 10:59 AM
Parallel vs. series filament supply - or another filament idea	engels	Tubes / Valves	11	13th May 2007 01:06 PM
When using a DC filament supply on a DHT...	Saurav	Tubes / Valves	31	18th September 2003 05:03 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

25th October 2005, 04:27 PM	#3
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Thank you Robert I have 6.3 volts, so I'll be using that. Glenn

25th October 2005, 04:33 PM	#4
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Is the 0.6A is for 2 tubes in parallel?

25th October 2005, 04:49 PM	#5
Yvesm diyAudio Member Join Date: Jul 2004 Location: Ardeche	Try to set heathers in serie: less current, easier to filter, smaller caps, lower current peaks a win win approach ! Yves.

25th October 2005, 05:05 PM	#6
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Using the series approach, if one tube heater fails the whole heater circuit fails, correct? I'm not sure this is a good or bad thing. I guess you can't use the circuit either way (series or parallel). The only hard part would be troubleshooting which tube failed. Glenn

25th October 2005, 06:28 PM	#7
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	You don't need to know the resistance if you use the constant current load option in PSUD2. Series or individual is much safer than parallel, because of the potential voltage rise when one valve is removed. Why do you need DC? It can be noisier than AC!

25th October 2005, 06:42 PM	#8
astouffer diyAudio Member Join Date: Jun 2004 Location: Pittsburgh, crumbling wasteland	How can DC be noiser than AC?

25th October 2005, 08:01 PM	#10
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Yes, I've never had a need for DC heaters in the past, but I like to have a "plan B" if needed. It's also another thing I'd like to experiment with just because I've never done it. This is for a line level 2 tube 6SN7 preamp, so the wiring is pretty simple compared to other jobs I've done. I never thought about the voltage rise if a tube is removed, good point. Of course I would never do such a thing Here's my layout so far: 6SN7 preamp Glenn

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)