??? 12/03/09 20:44 Read: times |
#171448 - a rose by any other name ... Responding to: ???'s previous message |
If you believe that a constant current can be generated without any sort of regulated voltage at some point in the circuit then it is you who needs to rethink his position.
Whether the thing is external or internal, it is necessary. If that weren't so, then you could easily generate a constant current from the mains without any rectification or voltage control at all! I challenge you to provide a schematic ... even one ... for a current source that is in no way dependent on some form of voltage control. That's been my entire point all along. First of all, Chico doensn't, nor has ever, in the course of this effort, required a current source, though you insisted that a voltage regulator was irrelevant. Secondly, you suggested that that shift-register-based LED driver was a current source suitable for his application ... which it is not! Third, you interjected yourself and your inane comment about current sources and laser diodes, where neither is germane to the discussion, when I suggested that Chico consider an adjustable voltage regulator because he was having trouble generating the required voltage. Not only was that particular voltage regulator very suitable for Chico's task, but in the event he should ultimately happen to want to generate a current source, it is quite suitable for that purpose as well. Moreover, it's a part he's likely to be able not only to afford but also to be able to find in his part of the world. Further, the LM317 is sufficiently useful that he'll undoubtedly benefit considerably from simply having worked with it a few times. Finally, you insist that you can produce a constant, regulated current, without any form of voltage control whatsoever, what it's called doesn't matter, and I simply invite you to produce it. Remember, though, it must be totally without external or internal voltage control, and not just some IC that hides it from you as does that LED driver, which, BTW, still doesn't function without a regulated voltage input, since the logic controls its outputs. RE |