# Ungula Components



## Diatrive (Feb 13, 2019)

Hello all, 

 There is a component labeled "RLED 4.7k"   Can someone help tell me what this is? I get the LED and maybe a red LED but why does it have a specification of 4.7k?
Thanks for any help!


----------



## Dirty_Boogie (Feb 13, 2019)

Diatrive said:


> Hello all,
> 
> There is a component labeled "RLED 4.7k"   Can someone help tell me what this is? I get the LED and maybe a red LED but why does it have a specification of 4.7k?
> Thanks for any help!


 The 4K7 (4.7K) resistor is the current limiting resistor (CLR) that is needed for the LED.  RLED just means "Resistor for LED".  Hope this helps.


----------



## Diatrive (Feb 13, 2019)

Ahh okay. That is just to tone down the light right? So I can leave it out?


----------



## Dirty_Boogie (Feb 13, 2019)

Diatrive said:


> Ahh okay. That is just to tone down the light right? So I can leave it out?


Nooooo!  If you don't use a current limiting resistor (CLR) with an LED, it will burn out within a few (milli)seconds.  It's definitely not optional.   It's also shown in the schematic for this build.  Do a quick Google search on "current limiting resistor LED" for more info.


----------



## Diatrive (Feb 13, 2019)

I am confused. I have never used a CLR and my LED's are ok. /shrug I put the LED in the LED shaped outline at the top of the PCB. 
I see this one in the schematic like you said. But I don't see it in the diagram.


----------



## JetFixxxer (Feb 13, 2019)

Diatrive said:


> I am confused. I have never used a CLR and my LED's are ok. /shrug I put the LED in the LED shaped outline at the top of the PCB.
> I see this one in the schematic like you said. But I don't see it in the diagram.



CLR must be part of the circuit that you used in the past.  Unless you have an LED with an resistor already installed.






						LED Current Limiting Resistors - SparkFun Electronics
					






					www.sparkfun.com


----------



## Dirty_Boogie (Feb 13, 2019)

Diatrive said:


> I am confused. I have never used a CLR and my LED's are ok.


 That's because there's already a 4.7K LED in all the builds - they might be listed as "RLED" (typically they're not). For the Ungula, in the build doc, it's listed as _RLED_:



In the PCB image on the product page, it lists it (in the same place) as a _4K7 _resistor:




If you have a spare LED, put the leads across a 9V battery (without a CLR) and see how long it lasts.


----------



## Diatrive (Feb 13, 2019)

Thanks folks. It makes sense now : )


----------



## Chuck D. Bones (Apr 16, 2019)

4.7K is a guideline.  It works well with red LEDs.  Different color LEDs have different voltage drops.  Red LEDs are about 1.6V, blue LEDs are closer to 4V.  Different LEDs have different brightness and the eye is more sensitive to red & yellow than blue.  I use 400nm violet LEDs (it's my personal trademark) with a 1.5K resistor instead of 4.7K.  Not only does it look cool, but the long-wave UV makes things some things in the room fluoresce AND my hands get tanned whenever I adjust the knobs.  Here's an unretouched photo of my Covert OD.


----------

