Another LED thread? Really?

theclerk74

Active Member
Simple question I think I know the answer to...

If I find 12v LED's, can they be wired in to both a CR 820 and CR 1040 without resistors?

I've been looking through some old threads and like the bluish color from white LED's. I've got a crap-ton of different resistors, and can use them if needed. But after helping my daughter with learning fractions, I feel my math skills have regressed to 6th grade levels. So trying to get the proper resistance is a little daunting.
 
i don't think there is such a thing as 12v led,s ..most likely around 3v .
they all need resistors to limit the current and lower the voltage ..well unless you already have a suitable supply that likely includes resistors anyway .
 
Well, I guess I misunderstood what I was reading. I'll go back and look. In my defense, it was after two in the morning.

I found a couple of LED's that say 12v forward voltage at 250ma. Of course I don't think the couple I found would fit in either receiver.

Is there anyone on AK that still makes the LED/resistors? The last thread I saw that mentions anyone is a couple years old.
 
Thanks for the link. Those are really cool LED's and an even cooler AK'er. Fuse style lights won't work in a CR though, will they?
 
Most cr units take a 14v bi pin lamp with a rubber sleeve over them to achieve the green , never seen fuse lamps in them. You will need a 360 degree led , the straight emitting leds don't light up the meters properly.
 
I'm thinking I'll go pick up some led's and try them with 120ohm 2 watt (?) resistors. I don't really understand everything... But I'm hoping that it doesn't have to be exact.
 
1/4 resistors should be fine .. try your 120 ohm resistor and measure voltage across the diode to see if its under the rated voltage ..
i am betting you might need something like 600 ohm or 1k .
 
If I understood it correctly, I'm assuming a voltage drop of 3.5v across the LED (white) and 12v supplied to the original bulbs. The calculator shows I should use a 470ohm resistor.

As soon as the wife rolls out of bed, I'll head over to the electronics supply store and see what they have for LED's.

I'll take pictures for documentation... Either for insurance purposes or to update this thread.
 
At some point when I have spare time (ha!) I need to do my Yamaha. My guess is that sanding the front of the LEDs will diffuse things enough- I hope. I'm really fussy about the intensity, and I usually use a resistance decade box to get the exact intensity I want, then solder in that value resistor.
 
Been there done that- it doesn't work well. The housing for the meters expects a 360 degree light spread, sticking a led in doesn't achieve that unless it's a 360 LED.
 
Well, I already bought the led's and resistors. According to the packaging, I got 5.1k 1/4 watt resistors, so it will be interesting to see how it goes. As far as narrow beam goes, I'll mess around with it. Maybe foil as a reflector? I'm curious about scuffing as well. I got some extra led's so I won't have to worry about screwing one up in the name of science.
 
i find putting led.s on the side rather than facing forward helps . can take a few attempts to set them just right .
 
Most cr units take a 14v bi pin lamp with a rubber sleeve over them to achieve the green , never seen fuse lamps in them. You will need a 360 degree led , the straight emitting leds don't light up the meters properly.

12volt
 
Okay, so I started with the CR 820. Good news is, nothing caught fire. Bad news is, the led's I got weren't nearly as bright as I'd hoped AND I believe they're only 20 degree viewing angle so the illumination is pretty dim.

I just finished ordering some 360 degree led's so when they show up, I'll give it another go.

a1d186af019067cb2d16e427d47058a5.jpg


It looks a little more blue than I had hoped for, but I'm hoping that it will improve with more light.
 
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Okay, got the 360 degree led's, found some 470 ohm resistors in my parts bin, did some soldering and this is what I got:

fecb42e1b716244e1b1a4364406df62c.jpg


67fc027760736c5dd240453ca7c49599.jpg


Time to close it up and work on the CR 1040.
 
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