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Total 8 documents matching your query.

1. [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: Kevan Nason <knason00@gmail.com>; Date: Tue, 8 Jun 2021 09:42:14 -0400; Thought Id try to save some people some frustration. Apparently, optocoupler LEDs have a lifetime. As they get old the light generated by the internal LEDs weakens and can reach the point where it is; /archives//html/CQ-Contest/2021-06/msg00081.html (9,440 bytes)
2. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Tue, 8 Jun 2021 11:22:34 -0700; This is an interesting situation to me since back in the 1970's I was the optocoupler product engineer at Motorola Semiconductor ... now OnSemi, and of course OnSemi acquired Fairchild several years; /archives//html/CQ-Contest/2021-06/msg00082.html (12,770 bytes)
3. [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: Kevan Nason <knason00@gmail.com>; Date: Tue, 8 Jun 2021 21:24:12 -0400; "It doesn't make sense to me to worry only about the two higher speed positions, since if the LEDS are degrading the slower positions are going to see the same problem soon after the higher speed pos; /archives//html/CQ-Contest/2021-06/msg00084.html (7,565 bytes)
4. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Tue, 8 Jun 2021 20:12:54 -0700; I suspect that the lower frequency ones aren't being driven with as much LED current. If anyone has the schematic they should be able to determine if that is true or not. Faster speed doesn't typic; /archives//html/CQ-Contest/2021-06/msg00085.html (10,348 bytes)
5. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: Ken K6MR <k6mr@outlook.com>; Date: Wed, 9 Jun 2021 05:19:00 +0000; My unit is pretty old and has all Fairchild (white devices). Ken K6MR I suspect that the lower frequency ones aren't being driven with as much LED current. If anyone has the schematic they should be; /archives//html/CQ-Contest/2021-06/msg00088.html (11,323 bytes)
6. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Tue, 8 Jun 2021 23:30:14 -0700; Yeah, that would be 5 milliamps for all of them, which certainly is not an excessive amount of drive current. Most application notes for optocouplers tended to spec about 10 milliamps for a typical; /archives//html/CQ-Contest/2021-06/msg00089.html (13,135 bytes)
7. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 9 Jun 2021 18:34:23 -0700; I was kind of sloppy there. Given the Vf of an infrared LED, the drive current would be less than 4 milliamps. 73, Dave AB7E Yeah, that would be 5 milliamps for all of them, which certainly is not; /archives//html/CQ-Contest/2021-06/msg00095.html (9,769 bytes)
8. Re: [CQ-Contest] Mk2R+ optocouplers (score: 1): Author: Ken K6MR <k6mr@outlook.com>; Date: Thu, 10 Jun 2021 13:21:25 +0000; Vf varies a bit from 1.2 V typical @ If = 10 mA, down to 1.0 V typical @ If = 0.3 mA. Youd think these things would last forever given the absolute max If is 30 mA. Interesting point though. I didnt; /archives//html/CQ-Contest/2021-06/msg00100.html (10,597 bytes)

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