Two series pairs; the heater transformer for the simple AC supply is 5V-0V-5V @3A.
Ray
25Hz DHT Filament Supply - How Would You Do It?
#18
Andrew, the answer to that is about hum reduction; each pair of series 300Bs is connected out of phase to promote some cancellation of noise. However, that isn't the crux of the issue, which is why DC heating can't be used and that is about the use of the current sink...Andrew wrote:OK, next question why do they need to be series?
thanks,
Andrew
Ray
#19
Hi Ray,
OK, but the current sink is on one end of the cathode right? What's on the other end?
While I don't believe BR doesn't know his onions, I just still don't get why a floating DC wouldn't work.
Andrew
OK, but the current sink is on one end of the cathode right? What's on the other end?
While I don't believe BR doesn't know his onions, I just still don't get why a floating DC wouldn't work.
Andrew
Analogue, the lost world that lies between 0 and 1.
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Paul Barker
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#20
I suppose it would be worth buying the book and modifying the circuit to accept cheap indirectly heated triode connected pentodes. Probably sound 95% as good, but a lot cheaper and no hum problems to engineer away with unusual heater arrangements.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
#21
The output and the current sink have a common connection to the cathodes - is that what you're asking?Andrew wrote:Hi Ray,
OK, but the current sink is on one end of the cathode right? What's on the other end?
While I don't believe BR doesn't know his onions, I just still don't get why a floating DC wouldn't work.
Andrew
Ray
#22
Yes, I think that's what I'm asking. The cathode has two pins, so physically one could be the output and the other the current sink, is that right?Ray P wrote:The output and the current sink have a common connection to the cathodes - is that what you're asking?Andrew wrote:Hi Ray,
OK, but the current sink is on one end of the cathode right? What's on the other end?
While I don't believe BR doesn't know his onions, I just still don't get why a floating DC wouldn't work.
Andrew
Ray
Andrew
Analogue, the lost world that lies between 0 and 1.
#24
Ok, so you have two filaments in series? or in parallel?
If in series is the CCS from the centre of the two and the heater on either rends (makes it a 10v heater). Or are they in parallel, the CCS and heater fro one side, and the heater the other?
If in series is the CCS from the centre of the two and the heater on either rends (makes it a 10v heater). Or are they in parallel, the CCS and heater fro one side, and the heater the other?
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#25
There are four output valves. Heater supply is 5V-0V-5V. Each 5V winding supplies two valves, (connected out of phase, i.e. one pin 1 and one pin 4 per pair). On the other side of the four cathodes there is a common connection with the heater supply centre tap, the output and the current sink. Sorry if I'm confusing you; as the saying goes, a picture is worth a thousand words.Nick wrote:Ok, so you have two filaments in series? or in parallel?
If in series is the CCS from the centre of the two and the heater on either rends (makes it a 10v heater). Or are they in parallel, the CCS and heater fro one side, and the heater the other?
Ray