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110VAC in 12vDC/2amp out

H

happyhobit

Jan 1, 1970
0
Hi Shawn,

Digikey has 12 VDC 2 amp wallwarts for $15 each

Jay
 
Shawn said:
Im looking to build a few power supplies that are able to put out 12vDC
at 2amps from a standard wall outlet (N.A 110vAC). I need 3 12v/2amps
power supplies to run three stepper motors. Any ideas or help would be
great.

thanks


If you are SURE you need only 2 amps, read on.
Below I describe building a 3 amp supply, or buying
one. Building a 2 amp supply would cost you only
a dollar less, not worth the savings.

Allelectronics sells a 3 amp 12 volt ac transformer
for $6.00 each. Catalog part number is CAT# TX-123
http://www.allelectronics.com/

Add a diode bridge rectifier (CAT# FWB-604) at 2 for $1.00,
a couple of filter caps in parallel) catalog # 4700/25VR
at $1.25 each and an LM350T regulator CAT# LM350T at $3.50
plus a couple of resistors and a diode, and you're done.
See the schematic at (watch the wrap):
http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm#317.gif
or Google on Bowden Hobby Circuits and click on
LM317 Variable Voltage Regulator. The LM317 is replaced
by the LM350T, which is a 3 amp regulator - the LM317 is
good for only 1.5 amps. I don't think you need the 22000 uf
cap - I'm betting the 2 4700's will be plenty.

You will need to heat sink the LM350T. Worst case, it will
dissipate about 10 watts, but with intermittent duty a small
sink will do - you can make on out of a small piece of
aluminum, say 2" x 2". (Bigger is better.)

The price tag per supply comes to $12.50, not including the
resistors, diode, enclosure, hardware, line cord etc.

Or you can buy CAT# PS-1242 for $18.00 - its a regulated
3.5 amp 12 v supply. That's probably cheaper.
 
S

Stu

Jan 1, 1970
0
Thanks for that timely info....was just about to send in an order to
them. ps...anyone in ontario know where to find atlest 3 (5 topes)
20.0mhz ceramic resonators....I dont want to order from the US ( I hate
duty charges) and I rather not just order one little part else were.
Digikey said they are out til the end of Febuary and well...I hope to
have toys to play with sooner then that lol
 
S

Shawn

Jan 1, 1970
0
Im looking to build a few power supplies that are able to put out 12vDC
at 2amps from a standard wall outlet (N.A 110vAC). I need 3 12v/2amps
power supplies to run three stepper motors. Any ideas or help would be
great.

thanks
 
D

Dave Cole

Jan 1, 1970
0
Im looking to build a few power supplies that are able to put out 12vDC
at 2amps from a standard wall outlet (N.A 110vAC). I need 3 12v/2amps
power supplies to run three stepper motors. Any ideas or help would be
great.

How well regulated do you want? You could want anything from a simple
12volt transformer and bridge rectifier on up to a switchmode regulated
supply. Many outfits (Digikey, ratShack, etc.) sell components or complete
supplies, depending on your requirements, budget, etc. Please specify.
Also, do you insist on separate supplies, or would one (12volt 6amp) do the
job?
Dave Cole
 
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