Need help on transformer selection!!

[spiderman2812]

I've been researching the westbury w-20. I've got everything I need to build one together except the transformer. I did some research and found this article with RG's input http://archive.ampage.org/threads/1/fxgd/003151/Retrannies_hold_up-1.html So I went to hammonds site to research the transformers he mentioned. Assuming that you can use one to get both the filament voltage and plate voltage. Now here is the real question assuming you can use just one of these to get the plate voltage for the westbury which one? Because according to the westbury diagram you need to have 200vac before going into the 4 diode rectifier. I am correct for assuming this right? Any help would be greatly appreciated in this matter this is the last step in building this pedal for me thanks. Here is the link to the westbury diagram also I have got some part #'s I think off of an original westbury t-former one of them is E3425 and the other is 42-117.

http://www.freeinfosociety.com/electronics/schemview.php?id=985

[R.G.]

I guess I'm going to have to sic the lawyers on FIS. They've removed my stuff twice now, but it just keeps showing up there.

As for your specific question - it doesn't matter a huge amount. 12AX7 circuits are remarkably resilient about what their plate supply voltage is. Anything between 150 and 300 will work with good results. That's why I did not feel the need to get a transformer with exactly 200Vac on a plate winding. You can practically drive a truck through the necessary specs on this one.
Reading the Hammond site,
- the 260A is an exact fit if you use a two-diode full wave rectifier instead of a bridge.
- the 261C6 is an almost exact fit if you use a two-diode full wave rectifier instead of a bridge.
- 262B12, 262B24, 262D6, 262D12, 262E6 and 262E12 all work fine if you use a doubler rectifier instead of a full wave bridge, and connect the filament voltages correctly (that is, 6V to filaments in parallel or 12V to filaments in series.)

Just from a quick look, Parts Connexion has the Hammond 262B12 for $20.88. Angela has the Hammond 262E6 for $18.99 and the 261E6 for $30.

You have made a serious mistake in your building process. As I pointed out over a decade ago in the Tube Amp FAQ, the thing you do first for any tube amp building project is to FIND THE TRANSFORMERS FIRST. Transformers have a huge effect on how something gets built, as they are relatively big and heavy, as well as expensive. If you build the rest of it first, you may well have to either give up the project entirely when you can't get transformers or rebuild it from scratch when you do get transformers.

[spiderman2812]

Thanks for the help RG. I haven't built it yet. I've just been working on the layout and figured I'd better find out about the transformer 1st. When I couldn't find any cross reference I stumbled on that archive on ampage. So now I can continue thanks to you. I'll let you know how the build turns out. Thanks again.

[R.G.]

Thanks for the help RG. I haven't built it yet. I've just been working on the layout and figured I'd better find out about the transformer 1st. When I couldn't find any cross reference I stumbled on that archive on ampage. So now I can continue thanks to you. I'll let you know how the build turns out. Thanks again.

Good man. I hate to get something all built and then find out I can't get some important part.

Some of the transformer options have different arrangements of rectifiers and heater connections. Yell if any of that is mysterious.

[spiderman2812]

I definetly will hit you up if I have any questions. Thanks RG you are a lifesaver!! I'm glad you're a part of this forum!!

[spiderman2812]

Would this work in the w-20 schematic if I just substitute it for the rectifier circuit using a hammond 262E12 transformer? Thanks

Here's the link to the doubler circuit I found 

http://people.seas.harvard.edu/~jones/es154/lectures/lecture_2/diode_circuits/doubler_2a.gif