Good cap reformer

[Bushbaby]

Hi All,
I'm keen for my next project to build a good cap reformer. I'm aware that there are several designs around but has anyone got a design that is a straightforward build, relatively low cost and all the components can be sought fairly easily?

Many thanks

Rob

[Ed_Dinning]

Hi Rob, come and find me if you are at Golbourne and I'll talk you through the design of mine.

Ed

[Yorkie]

I think this one is as straightforward a design as you are likely to find Rob, of which many have been built:

http://www.vintage-radio.com/projects/ca...ormer.html

I built the one that was in Jun/July 2008 Radio Bygones, and later in the BVWS Bulletin, which is a little more involved. I wrote it up on this forum back in May 2011. You'll find the thread here:

http://golbornevintageradio.co.uk/forum/...hp?tid=620&highlight=Capacitor+Reformer

I've updated that thread to highlight the error in the original circuit as to the wiring of the digital panel meter and have also attached to the thread a diagram of the correct way to wire the meter so that it does not share a common ground with the rest of the circuitry. I've also added the link to the RS site where the MOSFET can be obtained, presently at a price of 67p + VAT etc. The price of the digital panel meter back in May 2011 was £6.69, but is presently only £4.69 post free.

The reformer has proved most useful and more than paid for itself.

Hope that helps a bit.

[Bushbaby]

Hi David,
I was interested in the unit that you built but you did indicate at the time that the IRFBE20PBF MOSFET was problematic to get a hold of. It will be interesting to see if this is the case (probably worse) now?

Best Regards

Rob

[Bushbaby]

Hi David

do you have the original article that you can upload at please?

Best Regards

Rob

[Yorkie]

The MOSFET is available and in stock from RS for 67p Rob at this link: http://uk.rs-online.com/web/p/mosfet-tra...s/5429535/

As to the original article, both in Radio Bygones and the BVWS Bulletin, it is protected by copyright and can't be republished in the public domain without consent, but that isn't to say that it may not mysteriously find its way into your inbox from some anonymous source or another

If the occasional copying of BVWS Bulletin articles from past issues onto the forum with acknowledgement of the source is permissible (if only to show non-members what they're missing!), I'll be happy to do so.

Anyone care to comment on the latter point?

Incidentally, though I used two back to back transformers for the HT, there's no reason why a small mains transformer from a scrap radio can't be used. The 6.3V heater winding (rectified) could provide the power for the digital meter, most types of which must not share the same ground as the rest of the circuitry.

Hope that helps.

[Refugee]

The FET looks like a regular computer power supply type and could be substituted with a pull.

[Joe]

Incidentally, though I used two back to back transformers for the HT, there's no reason why a small mains transformer from a scrap radio can't be used. The 6.3V heater winding (rectified) could provide the power for the digital meter, most types of which must not share the same ground as the rest of the circuitry.

Another source for isolated HT would be transformer from a shaver socket. The other, direct-mains, design could also be fed from one.

- Joe

[Yorkie]

The FET looks like a regular computer power supply type and could be substituted with a pull.

It's described as an 'N-Channel MOSFET Transistor, 1.8A 800V' and states that it is used in a wide range of industrial applications, so I guess it could well find its way into PC PSUs.

[Yorkie]

Note: I've updated my original 2011 post, adding two attachments to it to highlight the the errors in the RB and BVWS Bulletin articles as to wiring the digital panel meter to make it clear that the meter must not share a common ground with the rest of the circuitry. (In fairness, the author's original meter may not have called for an isolated ground, but most on offer do).