Schematic and parts list for DC heater supply?

[dehughes]

So, I heard back from that Glass Ware guy regarding that H-PS-1. It can produce 6.3vdc from either a 5, 7, or 12VCT secondary. He recommends a 12.6vac PT in either 2A or 3A rating. That works for me, as I was planning on trying the "brute force" DC generation with a 12VCT filament tranny, so I could always use that same tranny to power his H-PS-1 board should I find that my DC isn't clean enough.

As well, he uses two 10k uf caps for the filtering...I was planning on only using one, but I'll get a few just in case. That H-PS-1 is pretty sweet, though....

[paulster]

You're basically good to go then.

I think you'll find you need 2x 10,000uF caps if you're trying brute force regulation as the ripple will be a bit high with just one. It kind of depends on whether you want to minimise AC hum or eradicate it!

[dehughes]

You're basically good to go then.

I think you'll find you need 2x 10,000uF caps if you're trying brute force regulation as the ripple will be a bit high with just one. It kind of depends on whether you want to minimise AC hum or eradicate it!

Eradicate it....like the plague. I assume there is essentially no AC hum on a 6v lantern battery, huh.

[paulster]

I assume there is essentially no AC hum on a 6v lantern battery, huh.

It's about as good as DC can get.

[dehughes]

Right on. The parts are on their way... I'll get to putting the amp back together and preparing for the new components.

BTW, I can probably hook up the filament transformer to the AC input in the same way as I did the PT, yes? That way I can use the mains switch to turn on both the filament tranny and the PT, right?

[Structo]

Correct

[drz400]

Well I missed the need for 6.3
For 12V you can use this
http://search.digikey.com/scripts/DkSea ... 02-1336-ND
There is a 5V version at 8A you can adjust up to 5.25V

[fishski13]

lurker, first post...hi. wonderful community here!

i put together a rectifier from this schematic (the top one), using a Hammond 269EX without a heater center tap:
http://www.diyaudio.com/forums/attachme ... 1202152318

i just finished it. it's a High Octane - has some tricked out LEDs, powered from the rectified DC heater supply. i don't play guitar - this amp is for an old buddy. i've been plucking out notes from a bass guitar into a 81 dB full-range test speaker.

i'm getting 6.0V with 0.33R x2 in series to the final smoothing cap per the schematic. the ground connection is directly to star-ground. any issues you guys can see?

my DIY background is hi-fi - 6.0V is kosher for filaments. should i shoot higher for a guitar amp?

thanks! :

http://i23.photobucket.com/albums/b353/ ... ild035.jpg

http://i23.photobucket.com/albums/b353/ ... ild036.jpg

http://i23.photobucket.com/albums/b353/ ... ild005.jpg

[Structo]

What do the led's above each knob do?

[fishski13]

What do the led's above each knob do?

provide a reference point for the for the knobs. they are intentionally dimmer - i'll let my friend decide how bright he wants them.

[dehughes]

Parts are in! Can't wait to get them installed (but I have to sleep...).

A couple of questions:

1) Filament tranny placement: Could I sandwich this in between the PT and OT, or would I be better served placing it away from the trannies (like on the side of the chassis on the PT end)?

2) Diode setup/voltage dropping: Now, my thought was to initially run one diode (MUR410G) on each side of the secondary, but then I've been told that if my voltages are too high that I could either run two in series off each side, or tack one on after the + side of the caps. Is one of those methods preferable? Does one drop more voltage than the other? Will those MUR410G diodes work fine for this?

3) Connected with the diode question...should I avoid using 1N4007 or UF4007 diodes for voltage dropping purposes, being as I'd be drawing .9A? Might I be better off using a larger diode (like a 5A/30v Shottky) instead?

Thanks! I'll get started tomorrow afternoon...

[paulster]

You'll need to be very careful about induced hum into the OT if you squeeze the filament transformer between the PT and the OT.

If you're familiar with the headphone trick then you could always try and see if it'll be an issue for you. Pull the output tubes, wire a pair of headphones to a mono jack and plug in to the speaker output of the amp, set it to 16ohm and then, with the amp off but the filament transformer powered (and the wires safely insulated), move it into position and see how much hum you hear through the headphones. That's noise being induced by magnetic coupling between the transformers. Once you've got a quiet spot, replace the headphones with a cabinet and see how it'll work in the real world.

As regards the diode, it'll make very little difference between putting a pair of diodes before the cap and a single one afterwards. In theory you'd be reducing your peak voltage before the cap and your rms voltage afterwards, so reducing the rms voltage would have a greater effect, but this would only be relevant to a regulated supply, so I'd go for whatever is most convenient in your layout. The MUR410G diodes look good as they're ultra-fast and 4A rated whereas 1N4007/UF4007 diodes will be running at their limit and won't enjoy the inrush current of cold heaters and then running right on the edge constantly. I'd use another one of these or similar as a voltage dropper.

Good to hear it's all coming together.

[Wayne]

If you've got lots of diodes, I would use one in each leg rather than using just one after the filter cap. With one diode in each leg, each diode passes the full current, but for only half the time. This means the average current in each diode is only half your total current draw = cooler, happier diodes. If you use one after the cap, it'll have to pass the whole current, the whole time.

W

[dehughes]

Thanks Paulster. I think I'll just put the filament tranny on the side of the chassis, away from the OT, and off-axis to the PT. It keeps it super close to the terminal strip with the diodes and caps that way, so it should be fine.

Wayne, I was intending to put one diode on each side of the filament tranny's secondary, but my options to reduce voltage are: 1) putting TWO in series on each side, and/or 2) putting another diode AFTER the cap(s). I was just curious if one was a "better" method...

Thanks!

[dehughes]

So, I've wired in the tranny, two 10000uf caps (in series), and one MUR410G on each side of the tranny secondary. The two diodes connect to the + of the caps. The - side of the caps is grounded close to the PT. The diodes are connected (correctly, I hope...), with the white side (cathode?) to the + of the caps.

Off the secondary, before the diodes, I'm measuring just under 7.00VAC on each side. However, after the diodes, I'm measuring about .002VDC. Something isn't right, huh.... Anyone care to show me the error of my ways?

THANKS!

[IMG768]http://i452.photobucket.com/albums/qq24 ... CF4533.jpg[/img]