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VR tube as bleeder in choke input supply?

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Posted on March 24, 2017 at 17:01:13
vbenonisen
 Is it a good idea to use a VR tube as a bleeder in the middle of a choke input supply (LCLC)to get above the critical current draw? More noisy than resistors? Ingnition with a loud bang in the speakers if used in a preamp?

 

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RE: VR tube as bleeder in choke input supply?, posted on March 24, 2017 at 18:02:12
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 IMO, the VR tube idea is very bad. If you can't tolerate the current loss and/or heat a proper bleeder resistor across the 1st cap. entails, use caps. that can tolerate the peak voltage produced by the power trafo. At turn on, the caps. can charge up to the peak voltage, but the rail voltage will drop, as the signal tubes start to conduct.


Eli D.

 

RE: VR tube as bleeder in choke input supply?, posted on March 24, 2017 at 22:14:19
Tre'
Industry Professional

Posts: 17296
Location: So. Cal.
Joined: February 9, 2002
 No matter where you put the vr tube, after the first L in the LCLC filter, it will have a cap across it.

I believe .1uf is max for a vr tube.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: VR tube as bleeder in choke input supply?, posted on March 25, 2017 at 00:12:27
vbenonisen
 Do you really have to have a cap across it? If you use the necessary dropping resistor to the VR tube then the following C shouldn't be connected directly to the VR tube at all. If I'm thinking straight. The tube isn't regulating anything. It just burns current and looks nice.

 

RE: VR tube as bleeder in choke input supply?, posted on March 25, 2017 at 05:49:15
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 It also generates noise. The snubber in parallel is necessary and the 0.1 μF. max. mentioned previously can, sometimes, put you into relaxation oscillator territory. :>((

Just put 1 Kohm of resistance (appropriate power handling capability) per H. of I/P choke inductance in parallel with the 1st capacitor. Remember, the approx. critical current (in mA.) is given by V/L. Larger inductance = smaller critical current.


Eli D.

 

RE: VR tube as bleeder in choke input supply?, posted on March 26, 2017 at 07:13:38
Triode_Kingdom
Audiophile

Posts: 10045
Location: Central Texas
Joined: September 24, 2006
 I don't think there's anything inherently wrong with this idea. I assume you would use a resistor in series with the VR tube(s). Do you have specific circuit values in mind?


 

RE: VR tube as bleeder in choke input supply?, posted on March 26, 2017 at 16:00:55
vbenonisen
 No, I just thought that it would make my choke input power supply a little more cool. I need to drop around 10-15mA and wirewound resistors are way more boring than VR tubes.

 

RE: VR tube as bleeder in choke input supply?, posted on March 27, 2017 at 12:24:29
Triode_Kingdom
Audiophile

Posts: 10045
Location: Central Texas
Joined: September 24, 2006
 Well, there's nothing wrong with the use of a VR tube to reach critical inductance. I would still install a high value resistor (not necessarily wirewound), just so the supply eventually bleeds down fully.


 

RE: VR tube as bleeder in choke input supply?, posted on April 5, 2017 at 08:31:43
schroeder715
Audiophile

Posts: 20
Joined: September 29, 2012
 Hello,

I´ve done it myself.

No noise added as well as no bang if you have another LC filter after the VR tube.

Best regards,
Martin

 

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