Re: Transformer wiring (for CNC controller, of course)

OK -

I figured it out. It all made sense once I realized that the 12V
wallwart I used was actually outputting 14.3V from 118.7V at the
outlet. It looks like each of the 2 120V primaries is tapped at
20V, thus the extra leads. (why?? Is this incase I have 220V
mains?)

Thanks for the help,

Carlos Guillermo
VERVE Engineering & Design

-----Original Message-----
From: mariss92705 [mailto:mariss92705@...]
Sent: Friday, February 22, 2002 4:11 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Transformer wiring (for CNC
controller, of course)

Carlos,

Here's what you can do with a small transformer and a digital
multimeter to identify what you have:

(1) Set the meter to Ohms and have a note pad and pencil handy.
Use
the ohmmeter to find continuity for all your wires. Write down
which
connect to which.

(2) Take a very small transformer (6VAC "wall-wart") and apply its
6
VAC to any winding pair.

(3) Set your multimeter to Volts AC and start measuring the
voltages
on the other winding pairs. The highest reading one will be the
primary. You already know the voltage ratios (120, 240, 86, 12,
etc)
so it should take very little time to puzzle out what is what.

(4) After you have identified the primaries, hook them in series.
Measure the voltage again. If you read "0" then you need to swap
the
wire making the series connection. If the voltage is twice what
you
had before, you got it right the first time.

You probably have a pair of 120VAC primaries (series = 240,
parallel
= 120). The 46VAC CT is probably what you need for CNC work. Wire
the
primary in series (240) and run it on 120. The 86VAC will turn
into
43VAC and give you 60VDC @ 20A. Nice supply.

Mariss


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