# LED Tester Box.. (A Must Have TooL)..



## ED-RRR (Jun 4, 2015)

This is the "Best Tool" to check actual "Brightness" of a LED.. 
This is a must have when requiring actual wanted LED brightness..
Some different colored LED's have different brightness values (MCD)..
When looking at LED's brightness values (MCD) the "Green LED's" is (x2) much brighter than "Red LED's" and "Yellow LED's"..

I have 3.MM (.118") Dia. round clear (foggy) LED's for my NJ track signals and NJ railroad crossing signals..
My biggest problem was to have the "Same" LED brightness for different colored LED's..









I used this "LED Tester Box" to change the LED (mA) "Input" to change the LED "Brightness"..
"LED Tester Box" indicates what (mA) I want for this LED "Brightness"..
Required resistor..
- http://led.linear1.org/1led.wiz
Source Voltage = V-DC power supply input..
Diode Voltage = V-DC required for the LED..
Diode Current = mA value from your LED "Testing"..









......


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## wvgca (Jan 21, 2013)

I had gotten a similar one, worked okay for approximate testing of brightness levels ... for closer matching I use a breadboard with resistors, the tester / driver I have just has six fixed current levels ..


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## T-Man (May 16, 2008)

I use 470 omhs for yellow and green and 1 k for red. Never thought it needed a gizmo.


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## ED-RRR (Jun 4, 2015)

*Different LED's (mA) Values..*



T-Man said:


> I use 470 omhs for yellow and green and 1 k for red.
> Never thought it needed a gizmo.


These resistors will work for *"Most"* (20mA) LED's..
*- But - *
I use 3.MM "Clear Foggy" colored LED's (With Different mA) (My Wanted - MCD Brightness) for each different colored LED for my *"Track Signals"..*
*- But -*
I use 3.MM "Warm White" colored LED's (With Different mA) (My Wanted - MCD Brightness) for my *"Street Lights"..*
*- But -*
I use 5.MM "Warm White" colored LED's (With Different mA) (My Wanted - MCD Brightness) for my *"Internal Structure Lighting"..*

*Fact:*
- Every "Different" LED "Application" will require a different "Calculated V-DC" power supply and the required "Resistor"..
......


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## gunrunnerjohn (Nov 10, 2010)

If you look closely inside that tester in the first post, you'll find that the currents depicted on the faceplate don't match the resistors inside. There are only three or four value resistors for the whole row, not what you'd expect to actually test at the current indicated.


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## wvgca (Jan 21, 2013)

gunrunnerjohn said:


> If you look closely inside that tester in the first post, you'll find that the currents depicted on the faceplate don't match the resistors inside. There are only three or four value resistors for the whole row, not what you'd expect to actually test at the current indicated.


John, I just looked up the OP's testers on fleabay, and most run only two and a half bucks [with free shipping], for that price it may be easier for many users to get one even just for testing to see if led's are good before install ...pretty good value .. I normally use a resistor of higher value, I model old era, and like the yellowish glow, and even coat them with Tamiya yellow to get the old kerosene light appearance .. the main reason that I got the one that I had pictured was that the socket would take the 4 pin style of led used in auto tail lights , sometimes sold as a "piranha' led .. it was around $20 or so, but used it a few times and cost was billed out to the repair jobs


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## gunrunnerjohn (Nov 10, 2010)

I bought one, that's why I know what's inside.  It's not bad, and I pull it out to check LED's, but it's also important to know what it isn't. I rarely run LED's anywhere close to their ratings, I prefer to let them loaf. The only place I get close is headlights, I love the look of the focused beam down the tracks, just like the real thing.


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## ED-RRR (Jun 4, 2015)

*LED Tester Box (Different Versions)..*



gunrunnerjohn said:


> If you look closely inside that tester in the first post, you'll find that the currents depicted on the faceplate don't match the resistors inside..
> There are only three or four value resistors for the whole row, not what you'd expect to actually test at the current indicated.


*[gunrunnerjohn]*
I am surprised that your "LED Tester" has only (x3 / x4) "Resistors" inside the unit..
You must have an *"Older"* version "LED Tester" with only (x4) resistance variables..

Facts: (Newer Advanced Version)
- There is now advanced electronic circuit board technology..
- There is a newer advanced version (LED Tester Box) with "Electronic Resistors"..










......


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## gunrunnerjohn (Nov 10, 2010)

Well, those are standard ceramic "surface mount" resistors, I have no idea what "electronic resistors" are. 

You obviously totally missed my point, I suggest you look a little closer, perhaps I can enlighten you as to what you're really looking at. BTW, I said *three or four value resistors*, and the correct answer is four.

R2 thru R4 are all 1.5k resistors
R5 thru R7 are all 680 ohm resistors
R8 thru R12 are all 360 ohm resistors
R13 & R14 are 240 ohm resistors.

There are only four values of dropping resistors, so there can only be four current levels for the top row.

The bottom row has only three values of dropping resistors.

R15 is a 51 ohm resistor
R16 & R17 are 120 ohm resistors
R18, R19, & R21 are 360 ohm resistors.
R20 is a zero ohm resistor, aka a jumper.

When you follow the PCB traces, it's obvious that the legends on the front don't match the resistor values on the back.

Now, it would have been possible for them to do a better job on the top row by actually using the proper resistor values, but they didn't do that.


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## wvgca (Jan 21, 2013)

nice photo of the pcb, I don't get that kind of close up clarity with my fuji S700


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## gunrunnerjohn (Nov 10, 2010)

WOW, I did it with my Samsung Note 4 phone, didn't feel like looking for the real camera.


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## BrokeCurmudgeon (Feb 8, 2016)

Gunrunnerjohn, could you please explain what the bottom two rows are and how they are used? My electronics training, courtesy of USAF, was well over 50 years ago. I appreciate your expertise. Thanks!


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## fcwilt (Sep 27, 2013)

gunrunnerjohn said:


> .
> 
> There are only four values of dropping resistors, so there can only be four current levels for the top row.


I am not familiar with that unit and I cannot see how the resistors are switched in/out.

Having said that it appears that perhaps any combination of those resistors can be placed in parallel - giving a wide range of current selection.

Yes? No?


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## gunrunnerjohn (Nov 10, 2010)

Switching the resistors would be a task for a soldering iron, you'd just use the proper value of SMT 805 sized resistors in place of all the duplicate values. That takes care of the top row. 

The bottom row only has a single resistor for multiple pins, so those are probably not all that flexible. 

My basic point was the legends on the front don't match what's in side the box.


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## fcwilt (Sep 27, 2013)

gunrunnerjohn said:


> Switching the resistors would be a task for a soldering iron, you'd just use the proper value of SMT 805 sized resistors in place of all the duplicate values. That takes care of the top row.
> 
> The bottom row only has a single resistor for multiple pins, so those are probably not all that flexible.
> 
> My basic point was the legends on the front don't match what's in side the box.


Below the row of resistors you can see a double row of solder pads.

I'm guess that the black thing on the front is a device for accepting jumpers (or something) to switch the associated resistor in/out of the circuit. 

This would explain why the label above the black thing appears to be marked for different currents.


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## gunrunnerjohn (Nov 10, 2010)

It's not clear what they were trying to accomplish with the bottom row, suffice to say it isn't "user friendly".


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## Mark R. (Jan 26, 2013)

I go even simpler .... clip a 5000 ohm potentiometer in series with the LED. Start the pot at the high end (5000 ohms) and turn it down until I reach the desired light level, remove the pot and measure the resistance across the pots terminals, use the closest value resistor available.

Mark.


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## wvgca (Jan 21, 2013)

Mark R. said:


> I go even simpler .... clip a 5000 ohm potentiometer in series with the LED.
> Mark.


too easy, lol ...


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## redman88 (Nov 25, 2015)

Mark R. said:


> I go even simpler .... clip a 5000 ohm potentiometer in series with the LED. Start the pot at the high end (5000 ohms) and turn it down until I reach the desired light level, remove the pot and measure the resistance across the pots terminals, use the closest value resistor available.
> 
> Mark.



Put it in a small project box with alligator clips on the top to hold the led. Then after you have found the brightness you want pull the led and test at the alligator clips. Less chance of changing the pot this way.


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## johnfl68 (Feb 1, 2015)

You would think that an *engineer* would have a proper *resister decade box* to use for this?


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## redman88 (Nov 25, 2015)

johnfl68 said:


> You would think that an *engineer* would have a proper *resister decade box* to use for this?


if i ever get around to going back to school for an Electrical Engineering degree like i want i will keep this in mind.


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## gunrunnerjohn (Nov 10, 2010)

Even us old engineers have test equipment, it's just a bit older.  I'll bet your test bench doesn't have these.


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## gregc (Apr 25, 2015)

gunrunnerjohn said:


> Even us old engineers have test equipment, it's just a bit older.


you must have worked for Thomas Edison or Marconi


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## gunrunnerjohn (Nov 10, 2010)

I confess, it was Marconi.


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## Lemonhawk (Sep 24, 2013)

Marconi, that explains a lot And I thought I was old. As an electrical engineering student I liked to use the meters that had mirrors. We also only had slide rules, always at our belts.

Chuck ONU '66


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## johnfl68 (Feb 1, 2015)

gunrunnerjohn said:


> I confess, it was Marconi.


I was hoping it was Nikola Tesla.


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## gunrunnerjohn (Nov 10, 2010)

I used to have a 6 foot Tesla coil that I made in high school shop. When I went off to the Navy, my brother traded it off.  They're not really that hard to build if you have a lathe, winding the secondary is most of the work. 

That actually looks more like a Van Der Graaf Generator.


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## wvgca (Jan 21, 2013)

Glad to see that you have moved up to the newer style of test equipment that actually has knobs instead of knife switches ... takes up a lot less room on the workbench .. 
speaking of workbenches, found this image on the net, if that's kinda like your workbench, I'm definitely jealous ..


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## gunrunnerjohn (Nov 10, 2010)

I'm afraid that my everyday test equipment looks nothing like that.


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