I don't think the transformer has been modified. I briefly clamped it to see whether it changed the noise level and it did but the resulting hum was still fairly audible.
No, I think the confusion is my fault for creating two threads. Cdbd is referring to my transistor.
Sorry for confusing things!
Sorry for confusing things!
Moved to I&AOP: Let me know if I need to clean up posts due to the thread confusion issue, send me a forum PM and let me know and I will remove the posts you indicate need to be removed. (Provide the post # of those you wish removed)
It tells us the power transformer might be OK, and the diodes too as long as the ballast lamp (your dim bulb) does not light.
Measure the B+ next. If you have not done so please read the following thread here:
http://www.diyaudio.com/forums/tubes-valves/30172-safety-practices-general-ultra-high-voltage.html
Optional, but likely helpful:
http://www.diyaudio.com/forums/tubes-valves/38278-line-tube-learning-newbies.html
Thank you Kevinkr, that's super useful. Can I ask what the B+ is? Really sorry if this is a stupid question.
Thanks for the links too.
The Tube/Valve guys/gals refer to the positive supply voltage as B+
I think the Russian for voltage begins with a B . It's on their capacitors !
I think the Russian for voltage begins with a B . It's on their capacitors !
the time honored term B+ is from the golden age of radio and to this day is used to refer to the power supply lines.
But only in certain parts of the world. Here we call it HT (or sometimes HT+), which may be why bloodtypw doesn't know what is meant by B+. Old-timers like me can mentally translate from Technical American to Technical English but newbies can't always do this.
^^^^^^ agree and add: realold tube stuff was not "consumer" stuff (yet) but "Lab" level stuff, only experimenters delved in Electronics.
And standard power source was *batteries* .
As a rough guide, tnhey were split in 3 groups:
"A" meant filament batteries, popular values were 1.5V (carbon cell batteries) , 2V (single lead acid cell) and 6.3V (3 cell lead acid cells, and the typical old car battery (think Ford T) so early tubed tended to use one of those values for filaments.
"B" meant high voltage batteries, a very popular value was 90V .
Not too practical trying to reach hundreds of volts, of course, although you could hook a couple 90V batteries in series, if needed.
Of course, stuff could easily be powered with 110VDC mains, which were very popular back in the day.
The +B name just carried on.
"C" were bias batteries . Usually with some funny chemistry which kept them stable for years (even decades) , as long as you did not pull any current out of them (mot even 1 uA) .
or you could use a tapped 9V battery (which of course is made out of 6 x 1.5V batteries in series):
And standard power source was *batteries* .
As a rough guide, tnhey were split in 3 groups:
"A" meant filament batteries, popular values were 1.5V (carbon cell batteries) , 2V (single lead acid cell) and 6.3V (3 cell lead acid cells, and the typical old car battery (think Ford T) so early tubed tended to use one of those values for filaments.
"B" meant high voltage batteries, a very popular value was 90V .
Not too practical trying to reach hundreds of volts, of course, although you could hook a couple 90V batteries in series, if needed.
Of course, stuff could easily be powered with 110VDC mains, which were very popular back in the day.
The +B name just carried on.
"C" were bias batteries . Usually with some funny chemistry which kept them stable for years (even decades) , as long as you did not pull any current out of them (mot even 1 uA) .
An externally hosted image should be here but it was not working when we last tested it.
or you could use a tapped 9V battery (which of course is made out of 6 x 1.5V batteries in series):
An externally hosted image should be here but it was not working when we last tested it.
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