PDA

View Full Version : Summary: Regulated Power Sources



Loren Chiu
01-03-2002, 02:12 AM
Thanks to all who replied. Most responses listed websites selling the
units, but there were also some detailing how to build the power supply.

After searching through the sites, it appears that the power supply
units are very cheap, and unfortunately the cost is less than the
"minimum purchase order." My inclination now is to scrounge through our
old computers (as suggested Kevin McQuade) for the power source, before
purchasing a new unit.

Below is my original request, followed by the websites selling the
units, and lastly the instructions how to build it.

Regards,

Loren Chiu
Graduate Assistant
Exercise Biochemistry Laboratory
Human Performance Laboratories
The University of Memphis

***Original Request***
I am looking for a 5vdc 150mA (min.) regulated power source for a linear
position transducer. The LPT manufacturer sells one for ~$80US,
however, I was informed that cheaper units were available. I've checked
the local electronics stores including Radio Shack (and their online
store) but have had no success finding one. It would be appreciated if
anyone could provide a low-cost source for this unit.

Commercial Sources:
http://www.power-one.com/
http://www.mpja.com/
http://www.jameco.com/
http://www.alliedelec.com
http://Digikey.com
http://www.flw.com/powerone.htm

Replies from:
Joe Hidler
Wafa Tawackoli
Jill Shea
Thomas Burkholder
Scott Tashman, Ph.D.
Chris Poletto

Building a Regulated Power Supply

Arthur Magill
If you're looking for a cheap, one-off solution, buy the cheapest
wall-wart type power supply you can find, outputing something over 8V
DC.
You should be able to find something for around $10. These devices are
notoriously noisy, but that's okay because you've got at least a 3V
margin. You can knock this down to a (clean) 5V using a regulator. A
regulator is a three pin device, looking like a transistor, designed for
cleaning up power supplies. You put in some volts, and get out an
accurate lower voltage. Try something like a 7805 (a couple of dollars
from Radio Shack). As you only need a small current, you won't even
need
to worry about a heat sink.

Kevin McQuade
Find an old computer and take out the power supply. The computer has a
regulated 5-10 v power supply (usually 5v). You will have to pull out
the unit and the switch and just splice out the wires to hook up to your
transducer - (also the position transducer probably does not need
exactly a 5 v power supply but usually can do well with a 7 v or 9 or
even a 10 v if that is all you can find) - just check the input voltage
range specs on the transducer - the only important key is that the DC
voltage not fluctuate (hence the term regulated) . You then just
calibrate the transducer to any voltage range that you have selected.

Second option - It is very easy to construct a regulated voltage supply
with simple radio shack parts and a battery. The circuits can be found
in most basic electronics books. if you are so inclined or know someone
with basic electronics knowledge it's easy. ( a 9v battery will give you
a regulated 5v output for a few months depending on how much you use it)

---------------------------------------------------------------
To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
---------------------------------------------------------------