12V AC to 6.3v DC simple supply for idiots

[DrewP]

Originally I was planning to slightly under heat the tubes in my 6CG7 and EL84 PP amp using a 12v AC supply, but I've been advised that I'd be much better off using a 6.3v DC supply instead.

Given that throwing another 12v AC toroid into the chassis is no drama, has anyone got a childs play circuit for giving a smooth 6.3v DC supply capable of feeding the heaters of 4EL84's and 2 6CG7's.

Rather have it regulated with a bit of spare current capacity so that a change in draw won't cause the voltage to droop than do it unregulated with a Pi filter.

Looking for cheap simple and pretty idiot proof.

An old HiFi World DIY supplement for their phono stage uses a bridge rectifier feeding a 4700uF cap into a 78S05 regulator with a pair of 1N4001's under its ground terminal outputting into a 100u cap.

This arrangement is only feeding a trio of ECC83's and a pair of 6922.s though.

[aardvarkash10]

check out the application notes for the LM3705. They show a current enhanced option using a basic transistor (can't remember which) to carry the main current.

[SpreadSpectrum]

There is an NJR 2396 6.3V fixed regulator that Mouser sells if you want something simpler. Current capability is not a problem if you split the load and use several of them, running them off of the same filter cap.

[Wavebourn]

Use 5.6V D5 for 6.3V

http://wavebourn.com/forum/download.php?id=116&f=7

[Bandersnatch]

Originally Posted by DrewP

Rather have it regulated with a bit of spare current capacity so that a change in draw won't cause the voltage to droop than do it unregulated with a Pi filter.

Looking for cheap simple and pretty idiot proof.

hey-Hey!!!,
The heaters are not going to change load demand. I'd suggest a full bridge and an LC-RC filter. You won't need much inductance, and 16V caps are available in low-esr in 15,000 uF about the size of my thumb.
cheers,
Douglas

[serph1nia]

You can use a CRC filter to make 12,6 volt and put two tubes in series.

EDIT:

12AC -> Bridge -> C (10000uf) -> R (adjust this one so you get 12,6VDC, use ohm's law) C- (10000uf) to one of the heater pins of a tube, then from the other heater pin to the heater pin of an other tube and then from the heater pin left to ground.

I'm a newbie myself so correct me if I''m wrong.

[Gorgomat]

12V AC - bridge rectifier - 4700µF 16-25V capacitor - 100nF 63V capacitor - LM317 regulator - 2k resistor adjust-output - 10k variable resistor adjust-ground.

[nigelwright7557]

I use a large capacitor, dropper resistor and a zener.

[pointy]

Bandsnatcher...............as far as I understand you will get some change due to electron emission in times of higher usage

something to do with cooling via electron emission

but don't ask me about it too much as it's just something I have heard of.

[pointy]

As a side thought could this effect be the reason why 2a3 valve like to go for a walk in usage?