CCS Red LEDs

arduino based linestage using 12B4 tubes

CCS Red LEDs

Postby jwhitmor » Tue Mar 10, 2015 10:07 am

I checked the forward voltage drop of the two red LEDs I grabbed for the 12B4 CCS circuits. The forward voltage drops measured 1.566 on one, and 1.602 on the other. Would there be any advantage to checking some more, and "hand matching" the volatge drops so they are close to the same?
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Re: CCS Red LEDs

Postby Geek » Tue Mar 10, 2015 10:33 am

0.036V is practically moot for a transistor, let alone a tube ;)
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Re: CCS Red LEDs

Postby Shannon Parks » Wed Mar 18, 2015 1:10 pm

Definitely that won't be a problem. Just try to keep them from the same manufacturer and model. A recent bag of Shenzhen red LEDs I purchased had three different types of LED inside, though it was labelled one part number. But I could see different cathode construction, so I could sort them.

The real rabbit hole is when you start testing them for noise. I've made a little low noise jig to test them with my audio analyzer and have tested hundreds of different LEDs lately.

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Re: CCS Red LEDs

Postby EWBrown » Wed Mar 18, 2015 3:57 pm

If you can find them, the HP HLMP6000 red LEDs are ideal for this purpose. Jameco might still carry them. I've checked dozens of them, all seem to fall into the 1.56 to 1.57 volt range. Doc Bottlehead uses the HLMP6000s, in many of his designs. They are a "halfway" between through-hole and SMD devices, the leads are very thin (ribbon-like), and very flexible. The cathode is the "silver" end.

Image "redistributed" from Bottlehead Website:

Image

If Jameco doesn't stock them any more, Bottlehead has them available at $5 for five.

http://bottlehead.com/product/hlmp-6000-leds/

Jameco HLMP6000 info: http://www.jameco.com/webapp/wcs/stores ... llDownView
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Re: CCS Red LEDs

Postby Geek » Wed Mar 18, 2015 8:15 pm

Mouser 630-HLMP-6000 - save yourself a ton of money.
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