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pshort

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About pshort

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  • Birthday 01/12/1955

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  • Location
    Pasadena, California, USA
  • Biography
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  • Interests
    Electronics...
  • Occupation
    Engineer
  • About my display
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  1. It also supports various DMX controllers.
  2. I think that this is one of the second batch of samples for the replacements...
  3. Check out last years threads regarding problems that people had with CDI LEDs...
  4. The capacitor may be another possible source of failure in a dimming application. In the static case the input AC voltage going to the string rises smoothly, and there isn't any discontinuity in the voltage on the capacitor. In the usual dimming circuit there may be a huge discontinuity in the voltage applied to the capacitor - either the result of the voltage on the cap decaying between successive AC cycles (if there is much voltage decay on the cap over the course of a cycle), or if the time of the triac firing varies as the result of computer command. The datasheets for electrolytic caps
  5. Play around with the parallel port mode settings in the computer BIOS. Some have found that setting the parallel port to EPP helps with this problem, but ymmv. You will probably get better attention and help for this particular type of problem if you post over on DIYC.
  6. Are you talking about a scheme where you have a long string of lights, where lights 1,5,9,13 come on first, then they go off and lights 2,6,10,14,... come on next, then lights 3,7,11,15, then lights 4,8,12,16, then repeat the sequence? And what type of lights do you really want (C7/C9, mini-lights, etc)? I don't know of any commercial solution, although I think that they do exist. Being a DIY-type of person, I would pick four sets of strings with a relatively large spacing between the lamps (perhaps 24", and twist them together with a 6" offset between each string, so that the resulting
  7. Don't forget that you need SSRs as well, they will end up costing a lot more than the Grinch controller if you are going for 64 channels.
  8. I'm not sure that I've seen anyone recommending the use of 14V with the MR16 lights. If you have the MR16 lights on hand, try them without any resistors at first. The discussions about using 22 Ohm resistors in series with the lamps was in reference to the MR16 lights that were being imported in 2007. The 2008 lamps were supposed to be the same as the 2006 lamps, which apparently worked ok without series resistors, and so you might try the current ones without as well. This is all being written without having any of the later lights on hand, so you should take this is just a starting point
  9. Another way to do it is to use small controllers that don't need much in the way of camouflage. Here is a photo of a prototype DIY controller for use with Vixen that I intend to build and use. It is fairly small (2" x 1.5"), so it can fit in either a small length of PVC pipe or a small project box, and can be potted or otherwise waterproofed. It's only good for about 0.8A per channel, but that is good enough for me. This is small enough that it can be easily hidden in the display (on the backside of a mini-tree, etc). As you can see, it isn't much bigger than the 8-function controller/li
  10. This is something that is relatively easy to add to (almost) any of the DIY controller firmware that I've been working on. The limiting factor is that Vixen doesn't currently support this functionality (and I don't know when or if this would occur).
  11. One way to do it without micros is to modify the venerable 555/4017 chase circuit which you can find everywhere on the web. Instead of driving each LED from one output of the 4017, you drive it from two adjacent outputs, using diodes (e.g. 1N4148) between each LED and the two outputs that it's connected to.
  12. There are some simple, inexpensive chase schematics out on the web that use just a 555 oscillator and CD4017 decimel counter (plus p/s and maybe a transistor buffer). Do a google on chase and CD4017, that should turn up quite a few links.
  13. I tend to agree that the whole UL approval aspect of those light strings is very suspect. I think that Paul would be well advised to get the UL certification information for both the replacement strings and the 2009 coop buy strings, and check them out very carefully to make sure that the information is legitimate and applies to the strings in question.
  14. You should have read a bit more, especially since there are quite a few threads on this topic. Regardless of what you or your friend who repaid (repairs?) power supplies says, those strings can be dimmed. I've seen it with my own eyes. The circuit does not use the caps as dropping elements. It uses the caps as storage or smoothing elements. Sorry, they do dim. Some of the components appear to be improperly rated, but that is a flaw that can be easily corrected (as they have). The problems here doesn't have anything to do with 'over there'. It happens just as often 'over here',
  15. This thread is heading south very quickly. From the other thread, the circuit in the CDI M5 100-ct strings is a voltage doubler circuit, with half of the circuitry in the blob/housing at one end of the string and the other half at the other end of the string. It is not a half-wave circuit, nor even full-wave, but closer to a DC drive for the LEDs. The caps in the circuit are probably not tantalum, because normal (non-wet) tantalum caps do not come with voltage ratings of more than 50V (at least not in the mouser catalog). Each of the capacitors in a voltage doubler circuit see just the o
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