Looking for little help with Glassware Janus shunt reg

[PJN]

Hi All,

I'm in the middle of assembling a Glass Ware Janus Shunt Regulator that I'll be using to power an Aikido line preamp. I'm using a torroidal transformer from Antek - 230 v and 6.3 v secondarys. I've got the heater voltage section working properly working properly, but I'm getting nothing out of the B+ section. I'm guessing it's because I don't have the 5 vac tied in for the rectifier tube heater. The documentation is a little thin and doesn't mention that I would need a separate 5 vac source for the rectifier heater, I would have thought that it would have taken the rectifier heater voltage from the 6.3 vac inlet, but looking at the board traces apparently it doesn't. Do you think that I could simply tie in 6.3 vac from the transformer secondaries to power the regulator heater, or should I get a 5 vac transformer ? the 6.3 vac secondaries are rated at 3A.

Thanks

PJN

[Rundmaus]

Hi,

you did not mention the type of the vacuum rectifier, but the following applies to most 5V heater rectifiers out there:

You need a *separate* 5V winding for the rectifier heater, as in most cases, the heater is internally connected to the cathode. This elevates the heater winding to B+ potential and therefore makes a shared heater circuit for rectifier and signal tubes impossible.

Greetings,
Andreas

[6L6]

Yes, the rectifier tube needs it's own 5VAC filament supply.

[PJN]

I'm using a 5Y3 rectifier tube. I'm a newbie with tubes and the point of needing a separate transformer was not in the documentation.Thanks for the info guys, I appreciate the help.

PJN

[6L6]

Some transformers have the 5v winding, some don't. Broskie does mention it in the documentation, but he is so enamored with some of the other points of the PSU (mainly the other heater supply) that he glosses over transformer requirements.

It's a neat regulator, I have looked at using it for a phono and linestage project that I hope to get around to some day.

[PJN]

I've been looking for a 5 VAC ~ 25 VA transformer and not having much luck, Antek is out of stock on a lot of low voltage transformers. Do you think that 6 vac is usable without damaging the heater, it seems to be a more standard item. Or do you have any recommendations where else I could look.

Thanks

PJN

[12B4A]

Use the 2nd seperate 6.3vac winding and drop down the voltage with a resistor. You're going to need anywhere from .68 to 1ohm of resistance that is rated for at least 4 watts. You'll have to experiment a little because line voltage and transformer regulation will affect the final value.

[6L6]

His transformer doesn't have a 2nd 6.3v secondary.

A separate 5v transformer is a better solution.

An example - Transformer - Hammond, Filament, 5 VCT, 3 A | Antique Electronic Supply

[12B4A]

Originally Posted by 6L6

His transformer doesn't have a 2nd 6.3v secondary.

A separate 5v transformer is a better solution.

An example - Transformer - Hammond, Filament, 5 VCT, 3 A | Antique Electronic Supply

Oh, I assumed that the transformer was this one because of the 3A rating.

[PJN]

Perfect, Thanks guys