I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks

--
Bart D. Hull

Tempe, Arizona

Check http://www.inficad.com/~bdhull/engine.html
for my Subaru Engine Conversion
Check http://www.inficad.com/~bdhull/fuselage.html
for Tango II I'm building.

Remove -nospam to reply via email.

On Fri, 19 May 2006 20:12:04 -0700, Bart D. Hull wrote:
I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Is that 6.3 v between these wires and the third wire?

Then likely the voltage between the hot wires themselves is 12.5v,
what you need.

i

On Fri, 19 May 2006 20:12:04 -0700, the renowned "Bart D. Hull"
wrote:

I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks


If it has three wires on the output side, one (typically the one that
is a different color) is a center-tap. You ignore that (put tape or a
wire nut on it) and use the other two for your 12V. If you connect any
of those three wires directly to any another the transformer will show
its extreme displeasure by getting very hot, smoking etc.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Fri, 19 May 2006 20:12:04 -0700, "Bart D. Hull"
wrote:

I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks
You have a center tapped secondary, for use with a 2 diode full wave
rectification circuit(not a bridge). You have 6.3 volts from common to
each end of the coil, and 12 volts from end to end. If you tie the 2
6.3 volt "ends" together you short out the secondary and get 0 volts,
and a lot of smoke.The two ends of the coil are phased in such a way
as to cancell each other.

*** Posted via a free Usenet account from http://www.teranews.com ***

On Fri, 19 May 2006 23:35:45 -0400, Spehro Pefhany
wrote:

On Fri, 19 May 2006 20:12:04 -0700, the renowned "Bart D. Hull"
wrote:

I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks


If it has three wires on the output side, one (typically the one that
is a different color) is a center-tap. You ignore that (put tape or a
wire nut on it) and use the other two for your 12V. If you connect any
of those three wires directly to any another the transformer will show
its extreme displeasure by getting very hot, smoking etc.


You most definitely do NOT want to let the "magic smoke" out!!!!!
Best regards,
Spehro Pefhany


*** Posted via a free Usenet account from http://www.teranews.com ***

Gentlemen,
Good thing I had a 1 amp fuse in the circuit so things didn't get too hot!

What is the "center tap" wire used for? I used the two similar colored
wires and got the 12v AC I wanted then used a single diode to get 12v DC
to run a fan motor. I don't imagine the left a extra wire to just put a
wire nut on. Should it be grounded?

How can I get some more speed out of the motor? Better rectifier setup?
Different transformer for more voltage?

The transformer is a 3amp 12v bare unit. (Not a power brick.)

Thanks for your help.

Bart


Bart D. Hull

Tempe, Arizona

Check http://www.inficad.com/~bdhull/engine.html
for my Subaru Engine Conversion
Check http://www.inficad.com/~bdhull/fuselage.html
for Tango II I'm building.

Remove -nospam to reply via email.

clare at snyder.on.ca wrote:
On Fri, 19 May 2006 23:35:45 -0400, Spehro Pefhany
wrote:

On Fri, 19 May 2006 20:12:04 -0700, the renowned "Bart D. Hull"
wrote:

I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks

If it has three wires on the output side, one (typically the one that
is a different color) is a center-tap. You ignore that (put tape or a
wire nut on it) and use the other two for your 12V. If you connect any
of those three wires directly to any another the transformer will show
its extreme displeasure by getting very hot, smoking etc.


You most definitely do NOT want to let the "magic smoke" out!!!!!
Best regards,
Spehro Pefhany


*** Posted via a free Usenet account from http://www.teranews.com ***

On Fri, 19 May 2006 21:38:43 -0700, Bart D. Hull wrote:
Gentlemen,
Good thing I had a 1 amp fuse in the circuit so things didn't get too hot!

What is the "center tap" wire used for?

As someone else said, could be used for a half wave 6v rectifier.

I used the two similar colored
wires and got the 12v AC I wanted then used a single diode to get 12v DC
to run a fan motor. I don't imagine the left a extra wire to just put a
wire nut on. Should it be grounded?

Does not have to be.

How can I get some more speed out of the motor?

One diode effectively only gives you half the cycles at 12V, sort of
like 6 v equivalent as far as power is concerned.

Better rectifier setup?
Different transformer for more voltage?

A better rectifier could help, yes. You need a full wave
rectifier. They are very cheap in your volt/amp range. I bought twenty
20 amp ones for $2.50 plus minimal shipping, a while ago.

i

The transformer is a 3amp 12v bare unit. (Not a power brick.)

Thanks for your help.

Bart


Bart D. Hull

Tempe, Arizona

Check http://www.inficad.com/~bdhull/engine.html
for my Subaru Engine Conversion
Check http://www.inficad.com/~bdhull/fuselage.html
for Tango II I'm building.

Remove -nospam to reply via email.

clare at snyder.on.ca wrote:
On Fri, 19 May 2006 23:35:45 -0400, Spehro Pefhany
wrote:

On Fri, 19 May 2006 20:12:04 -0700, the renowned "Bart D. Hull"
wrote:

I bought a 12v transformer from Radio Shack for my Powder Coater
project. It has two wires for the 120v input but three wires on the
output side of the transformer.

I show 6.3v on each of the "hot" wires on the output side. Do I just
twist the two wires together to get my 12V? Is this done to get more
AMPS out of a thinner wire winding?

I just know y'all have the answers I'm looking for.

Thanks

If it has three wires on the output side, one (typically the one that
is a different color) is a center-tap. You ignore that (put tape or a
wire nut on it) and use the other two for your 12V. If you connect any
of those three wires directly to any another the transformer will show
its extreme displeasure by getting very hot, smoking etc.


You most definitely do NOT want to let the "magic smoke" out!!!!!
Best regards,
Spehro Pefhany


*** Posted via a free Usenet account from http://www.teranews.com ***

Ignoramus23298 wrote:

On Fri, 19 May 2006 21:38:43 -0700, Bart D. Hull wrote:

Gentlemen,
Good thing I had a 1 amp fuse in the circuit so things didn't get too hot!

What is the "center tap" wire used for?


As someone else said, could be used for a half wave 6v rectifier.

You mean full-wave 6V. With the center-tapped transformer you only need
to use two diodes to get full-wave rectification -- which means you only
have one diode drop to contend with.


I used the two similar colored
wires and got the 12v AC I wanted then used a single diode to get 12v DC
to run a fan motor. I don't imagine the left a extra wire to just put a
wire nut on. Should it be grounded?


Does not have to be.


How can I get some more speed out of the motor?


One diode effectively only gives you half the cycles at 12V, sort of
like 6 v equivalent as far as power is concerned.


Better rectifier setup?
Different transformer for more voltage?


A better rectifier could help, yes. You need a full wave
rectifier. They are very cheap in your volt/amp range. I bought twenty
20 amp ones for $2.50 plus minimal shipping, a while ago.

More accurately known as a 'bridge rectifier'.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

"Bart D. Hull"

Do I just twist the two wires together to get my 12V?

Be very carefull...if you do it wrong that it will rip a hole in the
space/time continum and the universe will be sucked away! (But, where will
it go?)

On Fri, 19 May 2006 21:38:43 -0700, the renowned "Bart D. Hull"
wrote:

Gentlemen,
Good thing I had a 1 amp fuse in the circuit so things didn't get too hot!

What is the "center tap" wire used for?

It can be used for a rectifier as some suggest (although the voltage
is too low to reliably get 5VDC regulated out of it and it doesn't use
the core to full advantage), so that's not all that useful. The next
standard voltage up in the old days was double, so that was way too
much voltage for 5VDC (linear) regulated and wasted a lot of power,
but I digress..

The original reason was to operate vacuum tube filaments (it's called
a 'filament transformer' for that reason) and the center tap would be
grounded so the filament ends 'see' 6.3VAC relative to ground on each
side and line voltage hum is minimized. Kind of like the single-phase
120-0-120 system in US and Canadian houses*, but 1/20 the voltage. The
'neutral' (center tap) is grounded. Also, as in the house example,
it's flexible. You could power 6.3VAC and 12.6VAC loads with the same
transformer, and you don't lose any capacity if the loads are
more-or-less balanced. It's not an extra winding.. just a connection
to the middle of the 12V winding, so it doesn't add much cost to the
transformer.

* or the 55-0-55 system reportedly used on construction sites in Old
Blighty.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

"Bart D. Hull" wrote: (clip)I used the two similar colored wires and got
the 12v AC I wanted then used a single diode to get 12v DC to run a fan
motor (clip) How can I get some more speed out of the motor? Better
rectifier setup?
Different transformer for more voltage?
^^^^^^^^^^^^^^^^^
Chances are your fan motor is AC/DC. By using a diode, you are giving it
half-wave rectified DC, which means that 50% of the time the motor is
getting nothing. Try taking out the diode, and running the motor on AC,
which will give it twice as much power input. (If it uses permanent magnets
for the field, that won't work.)

That transformer is setup to be used in several different ways. Two common
setups for full wave rectification (what you want) is to use 2 diodes, both
pointed towards or away from the transformer, depending upon wheter you want
to have plus or minus relative to the center tap of the transformer or to
use a bridge rectifer setup (4 diodes and that can be had in a pack) to get
12V (actually you'll probably be getting about 18v or so if you use a
rectifier and no load) from the two end wires of the transformer. If you do
the bridge diode setup, insulate the center tap wire so that it doesn't
touch anything or you may pop the diodes and that is sad.
Most of the larger bridge rectifiers have markings on them to indicate the
use of the pins. There will be two marked with a sine wave (~) or AC whch
go to the transformerr and a Plus sign which is the pjositive pin and a
Minus sigh which is the negative pin of the bridge.

--
Why do penguins walk so far to get to their nesting grounds?