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Power Supply - Anode/Cathode

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andrewbutler(at)ireland.c
Guest

Posted: Wed Dec 31, 2008 2:52 am Post subject: Power Supply - Anode/Cathode

Hello,



I have no clue how to determine which is which. Can someone help? I have an electronic meter.



I bought a low rate power supply some time back to use to power non polarity sensitive flap motors and the like. I cut off the attached 12V socket connector and attached crocodile clips. I didn't take note which wire was anode or cathode.



Now I want to use it to power some of my avionics for testing etc. They are polarity sensitive.



Thanks,



Andrew.

 [quote][b]

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dale.r(at)cox.net
Guest

Posted: Wed Dec 31, 2008 5:03 am Post subject: Power Supply - Anode/Cathode

Andrew,



   I hope I'm understanding what you are asking.  To review: you

have a power supply that has unmarked terminals, and you have

a digital multi-meter or maybe just a DVM.  You want to know

how to determine - with the meter - the polarity of your power

supply?



   Your meter should have a black probe and a red probe.  With

the red probe's lead plugged into the Volt/Ohm jack and the

black probe's lead plugged into the "COMmon" jack, and the

range set to, say, 50vDC, attach your power supply's alligator

clamps to your probes. 



   If the reading is negative, then your probes are cross-wired,

so the clip on the black probe is the B+. If the reading is not

negative, then the leads are connected correctly and the clip

on the red lead is the B+.  Have some red electrical tape handy

to mark your power supply's  B+ lead.  Replace, when

convenient, with red heat shrink.



HTH,

Dale R

COZY MkIV #0497

Mesa, AZ

Andrew Butler wrote:

 	  Quote: 	
		   Hello,



 I have no clue how to determine which is which. Can someone help? I 

 have an electronic meter.



 I bought a low rate power supply some time back to use to power non 

 polarity sensitive flap motors and the like. I cut off the attached 

 12V socket connector and attached crocodile clips. I didn't take note 

 which wire was anode or cathode.



 Now I want to use it to power some of my avionics for testing etc. 

 They are polarity sensitive.



 Thanks,

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jaybannist(at)cs.com
Guest

Posted: Wed Dec 31, 2008 5:07 am Post subject: Power Supply - Anode/Cathode

Andrew,

 

 If I understand your question correctly, the answer is an easy one.  Use a mulitmeter.  If you have the wrong polarity, it will peg negative.  If you have it right, it will show 12V.

 

 Jay in Dallas

 

 

   

 

   

 

 --

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nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 31, 2008 8:00 am Post subject: Power Supply - Anode/Cathode

At 04:49 AM 12/31/2008, you wrote:

  	  Quote: 	
		  Hello,



 I have no clue how to determine which is which. Can someone help? I have an electronic meter.



 I bought a low rate power supply some time back to use to power non polarity sensitive flap motors and the like. I cut off the attached 12V socket connector and attached crocodile clips. I didn't take note which wire was anode or cathode.



 Now I want to use it to power some of my avionics for testing etc. They are polarity sensitive. 	


    Generally, the terms anode and cathode are used

    when referring to vacuum tubes, and chemical systems

    such as plating baths, batteries and dissimilar

    metals on boats. The source connections from a

    battery or power supply are more commonly referred

    to as (+) and (-) source connections.



    Most multi-meters don't identify their leads as

   (+) or (-) connections. For example:



  http://aeroelectric.com/Pictures/Tools/Test_Equipment/tenma1.jpg



   This instrument has a COMmmon jack with a black

   ring around it suggesting the black lead be plugged

   in here. There are two jacks for the red lead. One

   dedicated to high current measurements (20A full scale)

   and the other marked Volts-Ohms-mA for voltage,

   resistance and low current measurements.



   The instrument will indicate positive readings when

   the red lead is positive. Conversely, when the red

   lead is negative, the reading on the instrument will

   be preceded by a (-) sign.



   Not all instruments are set up exactly the same

   way . . . it's useful to study the manual that comes

   with it and then do some experimental measurements

   on your car, with a battery and light bulbs on the

   bench, etc. Become familiar with the instruments

   unique characteristics.



   Therefore, when set up as described above, probing

   the output leads for your power supply will no doubt

   produce a voltage reading . . . with polarity sign

   indicating which of the two test leads is positive.



   Your question suggests that you're just getting

   your feet wet in this electronic stuff. May I suggest

   a number of supplemental sources of information

   on the simple-ideas from which this craft is built?



   I recommend you acquire a copy of Electonics

   Fundamentals by T. Floyd. Don't get a new one. In fact

   get the cheapest one you can. The older editions are

   VERY reasonable.  See:



  http://tinyurl.com/94g8gb 



   Also, take a look at the first five books of a Navy

   electronics course that I've posted at my website.



  http://www.aeroelectric.com/Reference_Docs/Navy_Electroinics_Manuals/ 



   Finally, keep talking with us here on the List.

   You'll be hard pressed to find a more willing and

   able bunch of folks to help you out.



   Bob . . .

     [quote][b]

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andrewbutler(at)ireland.c
Guest

Posted: Thu Jan 01, 2009 5:32 am Post subject: Power Supply - Anode/Cathode

Very good. Thanks all.



Andrew.



---

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