Timeline for Hardware solution to fade LED on/off with digital output
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Mar 4, 2013 at 18:29 | vote | accept | rom | ||
| Feb 20, 2013 at 16:43 | history | edited | Oli Glaser | CC BY-SA 3.0 |
added 264 characters in body
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| Feb 20, 2013 at 16:38 | comment | added | Oli Glaser | @rom - I altered the circuits for more stable versions. Any of these should be suitable. The series options would be the best option if you have the supply headroom, but the parallel current source will be fine as long as you use the same transistors will reasonably well matched gains (if you have a transistor tester, you can hand pick them if you wish, but the current difference will be small anyway, and likely not enough to be visible) I added an IC example - you might want to have a look through all the other options too. | |
| Feb 20, 2013 at 16:33 | history | edited | Oli Glaser | CC BY-SA 3.0 |
Altered circuits and added IC option
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| Feb 20, 2013 at 15:23 | comment | added | Oli Glaser | @rom - as long as the transistors are of the same type and matched pretty well, the circuit should function okay. However, if you are worried about this give me a little while and I'll post a similar option that won't suffer from this problem, and controlled by a variable resistor for fading time (we can make the fade linear also). | |
| Feb 20, 2013 at 11:41 | comment | added | rom | Comprehensive answer, thank you. The RC setup is the closest to what I'm looking for, however LEDs fading out of sync with odd brightness levels doesn't sound promising. If I've got this right, would it not be possible to manufacture a self-contained IC with a variable resistor to change the RC value and ultimately adjust the fading time? | |
| Feb 20, 2013 at 4:05 | history | edited | Oli Glaser | CC BY-SA 3.0 |
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| Feb 20, 2013 at 3:35 | history | edited | Oli Glaser | CC BY-SA 3.0 |
Mentioned shortcomings of circuit
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| Feb 20, 2013 at 3:02 | history | edited | Oli Glaser | CC BY-SA 3.0 |
Fixed collector resistors
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| Feb 20, 2013 at 2:08 | history | edited | Oli Glaser | CC BY-SA 3.0 |
added 211 characters in body
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| Feb 20, 2013 at 1:54 | history | answered | Oli Glaser | CC BY-SA 3.0 |