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tester for LED signals

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  • Member since
    May, 2004
  • 4,306 posts
tester for LED signals
Posted by 7j43k on Monday, May 15, 2017 10:57 AM

I've got some BLMA signals that I want to start installing.  You know, the ones "they" don't make anymore.

To save up my store of expletives, I want to test the LED's as I go.

That is, I want to test each signal out of the box.  Then test each one during various installation steps.

What I strongly prefer is a battery-powered source to light them up, as opposed to using a VOM.  There is something so reassuring and definite about seeing that.

I figure it's a simple matter of assembling some cells and a resistor.  

I am seeking help on the number of cells (presuming 1 1/2 V) and the resistor.

All of this testing would be independant of the layout electrical--which isn't available at the moment--hence the simple and straightforward concept.

 

 

Thanks, 

 

Ed

  • Member since
    October, 2006
  • From: Western, MA
  • 7,389 posts
Posted by richg1998 on Monday, May 15, 2017 11:14 AM

Nine volt battery and 1k resistor. Many here have done that. Most LED's are 20 ma max. No calculations needed unless you prefer the math method.

You cannot use a ohm meter to check LED's, at least I have never been able to do that. I have used a meter to check diodes but not LED's.

If you want to see the current reading, you can buy a tester off ebay for under ten dollars which ships from China. I was in a DCC forum where some bought a tester like this.

I use a multimeter, 1k resistor and nine volt battery. Slightly lower reading than using twelve volts. With twelve volts I have measure, 9ma.

My first VOM was a Heathkit one I put together in 1954. Lasted thirty years.

Rich

N

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Monday, May 15, 2017 11:32 AM

I don't recall where I got this handy tester:

Yes, I know they're easy to make but this thing was around $10 and it clips onto a 9V battery and the mini gripper wire terminals are especially handy for the tiny signal wires.

Maybe it was Loy's Toys or Tony's Train Exchange? Anyway, I wish I had bought a few moreDunce  

There's a bunch out there shaped like a tombstone. They're OK for testing a new LED with the leads still intact but for something with fine wires already attached they are not suitable to stick the wires into the little sockets.

If you make your own, I suggest you use these mini-grabber type clips. Very handy for all styles of LEDs and small wire.

 I see LogicRail makes a "signal Tester" which could be handy.

https://tonystrains.com/product/logic-rail-st-1-signal-tester/

I would attach the test leads like Rich shows, below, to it. The screw terminals would be :Klutzy" at best.

Good Luck, Ed

  • Member since
    October, 2006
  • From: Western, MA
  • 7,389 posts
Posted by richg1998 on Monday, May 15, 2017 11:55 AM

I bought these many years ago. Cut some off and made my own test leads to use with my multimeters. Nice when working with components, DCC decoder wiring, etc.

http://www.apogeekits.com/images/smd_clip_test_leads.jpg

Rich

N

  • Member since
    December, 2004
  • From: Bedford, MA, USA
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Posted by MisterBeasley on Monday, May 15, 2017 12:37 PM

gmpullman
There's a bunch out there shaped like a tombstone.

Those are for testing Darkness Emitting Diodes, or DEDs, to make sure that they, like Generalissimo Franciso Franco, are still dead.

I use a 9 volt battery, a couple of clip leads and a 1K resistor.

It takes an iron man to play with a toy iron horse. 

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Monday, May 15, 2017 2:14 PM

MisterBeasley
Those are for testing Darkness Emitting Diodes, or DEDs

Oh! I thought they were for Life Extinguishing Die-odes Laugh

...and I have extinguished the life out of some LEDs, too Bang Head

Ed 

  • Member since
    May, 2004
  • 4,306 posts
Posted by 7j43k on Monday, May 15, 2017 2:27 PM

Thanks, all, for some very useful information.

I seriously don't want to keep installing a signal if it's not going to work.

And I am freely admitting that I will likely be the cause of the problem.

 

Ed

  • Member since
    August, 2003
  • From: Collinwood, Ohio, USA
  • 4,579 posts
Posted by gmpullman on Monday, May 15, 2017 8:11 PM

Found it!

http://www.ngineering.com/other_cool_tools.htm

Some signal systems use common anode LEDs while others use common cathode.

http://www.dccwiki.com/Signaling

The tester will help sort that out for you...

Good Luck, Ed

  • Member since
    May, 2004
  • 4,306 posts
Posted by 7j43k on Tuesday, May 16, 2017 12:11 AM

Neat.  

 

Thanks,

 

other Ed

  • Member since
    May, 2004
  • 4,306 posts
Posted by 7j43k on Tuesday, May 16, 2017 8:55 PM

I found another signal tester:  Logic Rail ST-1.

 

https://www.logicrailtech.com/xcart/home.php?cat=274

 

I can connect all four wires to it--there's a slide switch that will light each color.

 

Thanks again for your help,

Ed

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