my main transformer's 5V line is limited to 2A which limits the tubes that I can use. I have a 5V4G (5V@2A) now but it would be nice to have other options like 5U4G (5V@3A).
I have a 2nd transformer (that has 2 secondaries) which will be used to heat up 8CG7 (8.4V@450mA). I am hoping I can use the other secondary to heat up rectifier tubes using 5V.
Thanks for the help 🙂
ps. I know that tube data mentions AC/DC heaters can be used. but my experience with tubes amps is very limited and most schematics I've seen uses AC heaters. thanks again
I have a 2nd transformer (that has 2 secondaries) which will be used to heat up 8CG7 (8.4V@450mA). I am hoping I can use the other secondary to heat up rectifier tubes using 5V.
Thanks for the help 🙂
ps. I know that tube data mentions AC/DC heaters can be used. but my experience with tubes amps is very limited and most schematics I've seen uses AC heaters. thanks again
You can use a GZ34/5AR4 with a 2A winding, it only draws about 1.9A. It will also give you the lowest voltage drop of all tube rectifiers.
I've used regulated DC for DH tubes and have yet killed one.....
OK, I did blow up a 45 before I realized the meaning of soft-start
OK, I did blow up a 45 before I realized the meaning of soft-start
Geek said:I've used regulated DC for DH tubes and have yet killed one.....
OK, I did blow up a 45 before I realized the meaning of soft-start
I am planning to use one of the regulator chips from the LM317 family (higher current rating). would this be suitable? if not, can you share your schematic?
thank you
jarthel said:
It can work, but you'll need lots of caps before the regulator, probably large heatsinks on the diodes, and a large heatsink on the regulator. How about just using a resistor in series with the filament to drop a few volts?
dsavitsk said:
thinking of doing that and but no more DC. just use resistors to bring 9VAC to 5VAC.
Resistors is all I use. Chose the value for warm running, as the filaments are lower in R when cold.
I have a 9V secondary.
so I need to drop 4V from it.
4V / 3A (current rating for 5U4G) = 1.33ohms (5x 6.8ohms 5W in parallel)
4V / 2A (current rating for 5V4G) = 2ohms (5x 10ohm 5W in parallel)
Is my calculation correct? thank you
so I need to drop 4V from it.
4V / 3A (current rating for 5U4G) = 1.33ohms (5x 6.8ohms 5W in parallel)
4V / 2A (current rating for 5V4G) = 2ohms (5x 10ohm 5W in parallel)
Is my calculation correct? thank you
Also, keep an eye on the insulation rating of your 9V transformer. It may not be rated for safe operation with a winding floating at B+ voltage.
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