Re: [CAD_CAM_EDM_DRO] twin transformer ?

Hi Dave,

Sounds like an old ferro-resonant (sp) transformer. The 440V cap and
it's coil help to regulate the supply (more wires? might be also setup
for 50/60 Hz).

You've already identified the primary (115V, right?), and the secondary
with a bridge, filter, and bleeder resistor. Should be nothing else
connected? Assuming you're familiar with applicable ***SAFETY*** and
some electronics, I'd suggest you connect up the primary to 115VAC
through a 5A or so fuze, and meter the secondary (across the cap) and
see what you get!

Please don't proceed unless you are sure what you're doing! We'd like
to see you again! (no insult intended).

Should be fine for some Gecko's!

Alan KM6VV


dave_ace_me wrote:

>
> Hi,
>
> I was lucky enough to get a junk yard transformer/cap/set of diodes
> from what I think was some sort of telecommunications unit. It is
> marked ROLM Corporation on the enclosure and is dated 1983.
>
> There are two large transformers, some model or part numbers, but
> unfortunately no manufacturer name.
>
> One transformer has a 7" x 8" steel square frame and it has two sets
> of coils inside. One is a little over 5 inches in diameter and one
> and a half inches long, the other is also about 5 in dia and about
> 3.5 inches long.
>
> The main power is on the small coil and the output is on the larger
> one. The output goes to 4 diodes to get DC, and to a 68,000 uf / 75
> volt cap and above the cap is a label 48 Volts RMS. There is also a
> 100 ohm 55 watt resistor across the cap.
>
> The smaller coil has 5 leads, 2 are connected to input power and the
> large coil had 4 leads. 2 go to a set of diodes, I am sure to
> rectify the AC to DC. the other 2 leads on the large coil go to a
> small cap, 20uF 440 VAC. There is no connection between the two
> coils so one must feed the other thru the frame.
>
> Can anybody shed light on this thing ?
> Obviously, my first question is how much power would such a large
> transformer have ?
> and my second question is can I use it to drive a herd of Gecko's ?
> (a gaggle of Geckos?, flock...pack...)
>
> Then why the 100 ohm across the cap ?
>
> The other transformer is just a large unit, 5" x 6" on the frame and
> 4 inches dia on the coil and th coil is about 3.5 inches long. I
> think I should be able to figure this one out. Just keep adding load
> until it gets hot (?) 8 wires so I will have some fun figuring the
> combinations out.
>
> If anyone would like to see a pic, I could post some or e-mail.
>
> Dave