Dr.EM
New Member
Hello, i'm looking at building one of these;
**broken link removed**
I actually don't have a proper power supply around, and am using 12 AA bateries at the moment :shock: . I like the look of this because it has a wide voltage range which I frequently need. I don't need very much current either, so this should be quite substantial. I'll need to build version 2, as those 2k pots are indeed very illusive as dual gang.
Anyhow, i'm wondering about the transformer. There are 2 i'm looking at;
**broken link removed**
(last item, 20-0-20)
**broken link removed**
(50VA 25-0-25)
I see that the transformer requires earthing of the core, presumably to prevent the secondaries going live in the event of a serious failure. What i'm wondering is how to do this on product one. Is it simply a case of earthing that metal bracket? Is that in contact with the iron core directly or not?
I see that the toroidal type has the double insulation safety rating on the primary, which presumably exemplifies it from requiring an earth? But, I also hear that toroids have high inrush current and require a slow blow fuse, is that likely to have any side effects in this application?
I intend to install this into a plastic box, I see no point in making it metal, and I will have all the mains parts completely untouchable. The earthing (or not) is only to prevent the secondaries becoming dangerous in the extremely unlikely event of a transformer failure.
Also, the fuse is suggested as 2A. Should I lower this to my chosen transformers rating (ie, 1A)?
Thanks for any help
**broken link removed**
I actually don't have a proper power supply around, and am using 12 AA bateries at the moment :shock: . I like the look of this because it has a wide voltage range which I frequently need. I don't need very much current either, so this should be quite substantial. I'll need to build version 2, as those 2k pots are indeed very illusive as dual gang.
Anyhow, i'm wondering about the transformer. There are 2 i'm looking at;
**broken link removed**
(last item, 20-0-20)
**broken link removed**
(50VA 25-0-25)
I see that the transformer requires earthing of the core, presumably to prevent the secondaries going live in the event of a serious failure. What i'm wondering is how to do this on product one. Is it simply a case of earthing that metal bracket? Is that in contact with the iron core directly or not?
I see that the toroidal type has the double insulation safety rating on the primary, which presumably exemplifies it from requiring an earth? But, I also hear that toroids have high inrush current and require a slow blow fuse, is that likely to have any side effects in this application?
I intend to install this into a plastic box, I see no point in making it metal, and I will have all the mains parts completely untouchable. The earthing (or not) is only to prevent the secondaries becoming dangerous in the extremely unlikely event of a transformer failure.
Also, the fuse is suggested as 2A. Should I lower this to my chosen transformers rating (ie, 1A)?
Thanks for any help