New DHT heater - Page 53 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th August 2012, 02:51 PM   #521
Desmo is offline Desmo  Denmark
diyAudio Member
 
Join Date: Jan 2007
Location: Aarhus
Quote:
Originally Posted by Rod Coleman View Post
Yes, that's right.

Slow warming of the filaments is safer anyway, as the temperature will be more uniform.
OK, did some measurements...

At turn on the autobias pulls the grids down to -70V and it stays there for 45 seconds. After that the voltage on the grids slowly -over a few minutes- goes up to around -18V where it stabilizes.

15 seconds after the preamp is turned on the +B voltage comes on and ramps up during seconds.

30 seconds after the preamp is turned on the heater voltage is at 2,3V and I see the heaters glowing. It takes another minute or so before the voltage is at 2,5V.

So basically the autobias pulls down the grid longer than it takes for the heater voltage to come on, so I guess all is good..!?
  Reply With Quote
Old 4th August 2012, 05:31 PM   #522
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Hi Morten, the preamp has been designed very carefully, judging from those measurements - this is unusually good.

High quality 2A3s will last for 2000 - 5000 hours, using this kind of power supply.

A higher performance filament regulator was all it needed!
  Reply With Quote
Old 4th August 2012, 06:28 PM   #523
Desmo is offline Desmo  Denmark
diyAudio Member
 
Join Date: Jan 2007
Location: Aarhus
Thanks for your confirmation on the start up sequency Rod, this is very nice to know..!
  Reply With Quote
Old 4th September 2012, 10:31 AM   #524
50AE is offline 50AE  Bulgaria
diyAudio Member
 
Join Date: Jul 2011
Location: Sofia, Bulgaria
Hi there,

I like your project. I have an AC heated 6B4G SET amp and the combat with the hum seems beyond my strength.

Are there substitues for the ZTX849 the 2ST1480FP transistors?
If there are not, I will order them.

Thank you.
  Reply With Quote
Old 4th September 2012, 03:03 PM   #525
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Hi,

The old 2004 circuit uses transistors that are now unavailable. (But 2ST1480 was never used).

The Regulator that DIYers in this thread are enjoying, is a new design - a different circuit. The performance of this new circuit is much higher, and it's easier to use. It's available as a self-assembly kit, DIY-friendly price. Please send me your email address, if you would like some information!
  Reply With Quote
Old 13th September 2012, 07:09 PM   #526
diyAudio Member
 
slowmotion's Avatar
 
Join Date: Nov 2002
Location: Norge
Hi all,


I just received my regulator kits from Rod ( Thanks Rod! )
and am looking at what kind of capacitors to order.
Is it reasonable to assume that if I stick to for instance Nichicon or Panasonic
that looking at ripple current and load life will give some "safe" alternatives?
What else do I need to look for?


cheers

Jan
__________________
- Jan -
  Reply With Quote
Old 13th September 2012, 08:17 PM   #527
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Jan, there's some known-good caps for the rectified dc.

Panasonic TSUP is very dependable: the 1000uF/35V can be used in all cases: Farnell stock code 1198717

ECOS1VP103CA - PANASONIC - CAPACITOR, 10000UF, 35V | Farnell Norge

High ripple current handling is the most important data sheet point.

Enjoy the DHT upgrade!
  Reply With Quote
Old 14th September 2012, 12:43 PM   #528
GeirT is offline GeirT  Norway
diyAudio Member
 
Join Date: Aug 2011
Location: Oslo
This is what I would call a comprehensive customer support!
I'm in the process of building a power supply for the Coleman heaters too so this info is welcome :-)

Quote:
Originally Posted by Rod Coleman View Post
Jan, there's some known-good caps for the rectified dc.

Panasonic TSUP is very dependable: the 1000uF/35V can be used in all cases: Farnell stock code 1198717

ECOS1VP103CA - PANASONIC - CAPACITOR, 10000UF, 35V | Farnell Norge

High ripple current handling is the most important data sheet point.

Enjoy the DHT upgrade!
  Reply With Quote
Old 14th September 2012, 12:50 PM   #529
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
I should mention as well, that if your raw dc supply is below 16V, there's an excellent bargain cap available at the moment: Farnell 1839273 is an EPCOS 10000uF/16V that can support 3,3A of ripple:

B41231A4109M000 - EPCOS - CAPACITOR, SNAP-IN, 16V, 10000UF | Farnell Norge

very low cost for a high quality snap-in. Ideal for 300B, 26 and similar power filaments.
  Reply With Quote
Old 14th September 2012, 05:28 PM   #530
diyAudio Member
 
slowmotion's Avatar
 
Join Date: Nov 2002
Location: Norge
Thanks for the information Rod!

Just decided this is a good time to get new tips for my soldering station.
Should have done that ages ago anyway.


cheers
__________________
- Jan -
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
how to wire 6.3VDC heater on a heater with center tap (12.6V series, 6.3V parallel)? jarthel Tubes / Valves 9 14th April 2012 06:36 PM


New To Site? Need Help?

All times are GMT. The time now is 02:43 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2