Schematic and parts list for DC heater supply?

[paulster]

Cool. So in looking at different transformers, the 187C10 seems to be a good fit for what I'm doing. I think I can mount it on the outside-side of the chassis, and then mount the circuit board on the inside side opposite the tranny, and both will be located close to the power supply and be out of the way of any preamp wiring, etc..

The only thing I don't like about this transformer is that it doesn't have self leads, which means there's the potential to have 120Vac available outside the chassis. Looking at the pictures of it, it would appear that even when heat-shrinking over the blade connectors you'll still have a short piece of enamelled wire disappearing into the coil that's been stripped back. It's your amp and you'll be careful but it's worth considering how to minimise the risk to others, particularly if you ever sell it on.

Take a look at this page for an example solution:
http://www.ampmaker.com/pt02x.asp
I wonder if Hammond do a sleeve like this at all, which would completely solve that potential issue.

I'll put in the order tomorrow or Thursday, so if anyone has other tranny recommendations, lemme know, as I only want to buy one...and the right one. I'm still waiting to hear back from that Glassworks place, as to what type of tranny they'd recommend to run their H-PS-1....

It's a good idea to ask them what they recommend as they'll know the voltage you actually need to get a stable 6.3Vdc out of the card with the components they've chosen.

[dehughes]

Nice. Thanks, Paul! I'll post back when I hear back from Glassworks...

[dehughes]

So, the 166L10 seems to be a good option....leads as opposed to terminals, and a bit more current handling:

http://www.hammondmfg.com/pdf/5c0018-19.pdf

[paulster]

That one definitely looks good. Remember to cap off the centre-tap and just ground the DC side since you'll have an isolated supply now.

It'll still hum like crazy on DC if there isn't a ground reference.

[dehughes]

That one definitely looks good. Remember to cap off the centre-tap and just ground the DC side since you'll have an isolated supply now.

It'll still hum like crazy on DC if there isn't a ground reference.

Right on. Thanks.

So again, why can't I ground both the DC and AC supplies? Or can I?

[paulster]

On your 6.3Vac supply to your power tubes, ground it as normal (centre-tap).

On your new 6.3Vdc supply, which is completely independent, cap off the centre-tap of its transformer and ground the DC side only.

You'll end up with the power tubes on ground-referenced AC and the preamp tubes on ground-referenced DC.

That'll be the quietest option.

[dehughes]

On your 6.3Vac supply to your power tubes, ground it as normal (centre-tap).

On your new 6.3Vdc supply, which is completely independent, cap off the centre-tap of its transformer and ground the DC side only.

You'll end up with the power tubes on ground-referenced AC and the preamp tubes on ground-referenced DC.

That'll be the quietest option.

Right on. So that would look like running a connection to ground from either the PCB (if using a regulated supply) or the - of the cap (if going with "brute force" DC), right? That is, ground referencing that supply once it has become "DC"....

[paulster]

Exactly.

[dehughes]

DUDE, this guy at GlassWare Audio Design still hasn't gotten back to me as to what tranny I should use with that regulator supply. I'm itching to get started.....but don't want to order the wrong tranny. Patience, David. Patience.

[drz400]

DUDE, this guy at GlassWare Audio Design still hasn't gotten back to me as to what tranny I should use with that regulator supply. I'm itching to get started.....but don't want to order the wrong tranny. Patience, David. Patience.

John Broskie?
Busy man and doesn't really care about simple questions. I would not expect an answer. Are you talking about the Janus Kit? I dont see a heater supply PCB separate from the preamp, where is that link?

Why dont you use 12VDC (pins 4&5, no 9), dont worry about the Phase inverter. Easier to deal with 1/2 the current this way and can use a 1.5A off the shelf 12V regulator isolate and attach to the chassis for a heatsink. I still say though unless you are willing to etch a board and learn about supplies that DC supply I linked to is $30 and takes 10 minutes to install as long as you have space, no transformer needed, no board making. I have used that supply many times. It even has a trimmer on it so you can dial it in to 12.6 but personally I like 12.

[dehughes]

Huh. Thanks drz400.

Here is the link:

http://glass-ware.stores.yahoo.net/hps1.html

This seemed to be good enough, but figured I'd need a PT to supply it...just didn't know what rating, etc... I'm leaning to a 10v tranny with at least 1.2a capacity.

Would you be so kind as to point me towards the type of regulator you use (Mouser link)? That'd help me get a better understanding of what I'd look for.

I'm also tempted to try the "brute force" regulation way, as it would be cheaper...but...then I don't want to cheap out and find I need to go back and do it again. However, that's how Komet runs their Constellation, and I've never heard anyone complain about noise, so it must work alright. Hmm...

WHICH, brings up another point: Doesn't a 6SN7 have a max heater voltage of 6.3v +/- 5%? So, then I couldn't run it at 12v, and the Constellation probably didn't do that either. That is, on the Constellation there is a winding going to two diodes, which then connect to a 10000uf cap, which then connects to pins 4 and 5 of the 12AX7 and pin 7 of the 6SN7. Pin 9 on the 12AX7 and Pin 8 on the 6SN7 are connected to ground. As well, on the chassis of the Constellation, there appears to be a filament transformer next to the PT.

I suppose I could ask the Komet guys what they used....I'm thinking a 12v CT tranny into two diodes and a cap giving up 6v or so.

[paulster]

12V is not an option for you unless you get a 12SN7 so I'd stick to plan A.

There's no reason why you couldn't get a tag strip, a pair of 10,000uF caps and a bridge rectifier module and make a temporary DC power supply that you tack in to test before committing yourself to the regulator. That'll only be a few bucks in parts and if you're happy with the result then you can save yourself the cost of the transformer and the regulator board and just build it up into something a little more roadworthy.

[dehughes]

12V is not an option for you unless you get a 12SN7 so I'd stick to plan A.

There's no reason why you couldn't get a tag strip, a pair of 10,000uF caps and a bridge rectifier module and make a temporary DC power supply that you tack in to test before committing yourself to the regulator. That'll only be a few bucks in parts and if you're happy with the result then you can save yourself the cost of the transformer and the regulator board and just build it up into something a little more roadworthy.

Right on. I'm going to do that, then. I'll get a 12VCT filament tranny which will kick out about 2A or so and then use a tag strip and a couple of low loss diodes (is there such an item?) to get me in the 6v range, along with a 10000uf cap (or two...I'll purchase a few extra) and see what kind of ripple that leaves me, and if my 6SN7 can live with it. If not, then I'll go the regulated mini-board route like that VOF-65 or the H-PS-1.

Paulster, you're awesome. You need a medal. All of you do....really..drz400, phil, etc. etc... So helpful. Thank you guys so much.

Now I'm off to Mouser (or Newark?) to find some good quality diodes. I think I'm going to purchase a bunch of 1N4007 to have around (any recommendations as to brand? Or does that matter...) as well as a couple of Schottky diodes (again, recommendations? Or just use the ones mentioned previously in this thread...), and then a few of those bridge rectifiers and regulators you all mentioned. That should give me enough stuff to "tinker" with...

[paulster]

No problem. That's a great build you've got going there so it'll be nice to see it finished off properly and living up to its potential.

Regular 1N4007s will do you fine for this, although I'd always use UF4007s instead to reduce switching noise. Brand doesn't make any difference as the specifications are all the same.

You might find that your rectified voltage is too high on the 12V tranny using a single diode on each side. If that's the case then put another diode in series (like a typical HT supply) and you'll drop another volt or so.

If you want to use Schottky diodes then my favourite are MS503, which seem all but extinct now (I bought the last stocks from two major UK suppliers). They have a tiny forward voltage of 0.49V at 5A, in a regular cylindrical package. The closest I've found to these now are SR503 (clearly intended to be a replacement part) that have a Vf of 0.55V Vf at 5A.

Because I run my boards off 6.3Vac and generate 6.3Vdc off of that, I have to be pretty picky about my diodes, especially as the current has to traverse two of them in a bridge rectifier configuration.

[dehughes]

RIGHT ON

I'll be buying things this weekend...


Thanks so much.