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Richard Erlacher
12/03/09 14:13
Read: 537 times
Denver, Co
USA


 
#171449 - What are you trying to prove?
Responding to: Per Westermark's previous message
Per Westermark said:
The component I linked to would manage reasonably well with a 11V p-p sine wave with a 24V DC offset.

A suggestion of 11V DC with 24V p-p AC would mean -1V to +23V.

I challenge you to get a 7805 to manage with such input and no cap, coil or other hardware to filter the input.

I didn't say it would. All I did was to mention that an LM317 might provide Chico, the O/P, with a useable 3v3, or whatever, voltage supply.

Now, please stop writing ridiculous posts and return to earth. You are fighting an argument that is silly, and you are trying to smash in open doors - no one has every claimed that a CC regulator can invent current. And no one is really interested in the actual circuitry inside a CC regulator just as people do not care too much about the innards of a 7805 regulator. You aren't scoring any points with your posts. Just making people look for the "ignore poster" button.

I'm not into scoring points, though I submit that apparently, rather than exposing useful information, you and Erik have both taken to shouting "I'm right and you're wrong!" even if the argument is entirely irrelevant to the discussion.

Nobody brought up current sources until Erik jumped in with his foolish remark about laser diodes being current devices. While that might be true, it certainly wasn't relevant to what was under discussion. Then, he went on to suggest that his LED driver would "do the job" without a regulated supply, which it would certainly not.

Rather than wasting more time and bandwidth on this unproductive line of rhetoric, why don't you tell us what it is you want to prove. It's certainly not been stated so far, and it certainly isn't relevant to this thread. Erik made an unsupported claim, probably just because of poor wording, but one that's irrelevant to the thread.

He did make an important point, that being that one shouldn't buy a device for which he needs precise specifications, when it's not possible to get them. That's something he's mentioned before, and people should pay attention! The device in question is apparently a laser pointer ... one that's no longer offered on eBay, and whose seller is no longer offering anything on eBay. I found that none of those similar devices still offered on eBay have specifications available. Those are, after all, commercial off-the-shelf devices that come with instructions but not technical data. It's important to know what you're buying. Erik pointed that out.

I've often had to prod Erik considerably when he's been loath to provide examples of things he believed existed. I recall one instance regarding LCD modules, where, after much prodding, he actually provided a link to an LCD supplier whose bias voltage was positive. While I didn't deny that such things existed, having, in fact, had one on my desk at the time, I challenged him to produce an example. After all, it was his baby! He had made the assertion a that such things were "out there." Ultimately, he produced it.

Now, what have YOU contributed to this thread? Is it possible to generate a constant current source, irrelevant though it may be, that in no way utilizes, at any stage in its operation, a controlled, precise, regulated, or whatever you choose to call it, voltage supply/bandgap/reference/zener? If so, why not simply show it to us? Why go on and on saying "there are such things" when you have no example? Someone, somewhere, might benefit from seeing such a thing!

RE








List of 168 messages in thread
TopicAuthorDate
Trouble with a simple project with ULN2803      Chico Magalhães      10/06/09 16:38      
   Start to search step by step      Per Westermark      10/06/09 17:18      
      back to breadboard      Chico Magalhães      10/06/09 17:53      
         No surprise...      Kai Klaas      10/06/09 19:40      
            Thanks Kai      Chico Magalhães      10/06/09 21:00      
               In short      Neil Kurzman      10/06/09 22:17      
               Then have a look at the datasheet!      Kai Klaas      10/07/09 10:14      
                  Don't think so      Per Westermark      10/07/09 11:09      
                     No, Per, the actual reason is...      Kai Klaas      10/07/09 16:59      
                        'working' again      Erik Malund      10/08/09 05:08      
                           But why?      Kai Klaas      10/08/09 09:39      
                              Lack of knowledge of the unknown      Per Westermark      10/08/09 12:29      
                                 Ah yes      Steve M. Taylor      10/08/09 13:01      
                                 I think people don't just realize how much they do not know.      Andy Neil      10/08/09 14:17      
                              There is a reason ...      Richard Erlacher      10/08/09 23:47      
         why was working with the other microcontroller      Andy Neil      10/07/09 01:41      
            Keep in mind it's on a "breadboard"      Richard Erlacher      10/07/09 14:05      
               Infinite Improbability Drive?      Andy Neil      10/08/09 01:01      
                  re: Infinite Improbability Drive      Andy Peters      10/08/09 11:06      
                     Pah      Steve M. Taylor      10/08/09 11:36      
                        Vote: Offensive/Flame!      Andy Neil      10/09/09 00:33      
                           ;-)      Steve M. Taylor      10/09/09 00:40      
                              Reference for the uninitiated      Andy Neil      10/09/09 02:49      
         Without pull-up???        Per Westermark      10/07/09 02:06      
         because it was not working, but 'working'      Erik Malund      10/07/09 07:58      
   What else is on your board...      Andy Neil      10/06/09 17:23      
   It's a transistor array ... not a magic box      Richard Erlacher      10/07/09 08:35      
   AGAIN!!! =(      Chico Magalhães      11/10/09 19:52      
      What are you connecting to outputs?        Daniel Contarino      11/11/09 01:09      
         Yes...!      Kai Klaas      11/11/09 08:57      
            new measures with load      Chico Magalhães      11/11/09 09:37      
               How?        Kai Klaas      11/11/09 09:45      
               Can use an oscilloscope?      Daniel Contarino      11/11/09 09:55      
                  Laser and oscilloscope      Chico Magalhães      11/11/09 10:20      
                     Need current control, not voltage control      Per Westermark      11/11/09 11:26      
                        re Per      Erik Malund      11/11/09 11:43      
                           Definitely a good way go let out the magic smoke      Per Westermark      11/11/09 12:03      
                              not even then      Erik Malund      11/11/09 12:34      
                                 The problem is not the laser.      Chico Magalhães      11/11/09 13:45      
                                    Drive the ULN harder.      Per Westermark      11/11/09 14:22      
                                    Factor 10 off?      Per Westermark      11/11/09 15:55      
                                    I guess, you forgot the Ucesat of ULN2803...      Kai Klaas      11/11/09 19:00      
                                       74HC04      Chico Magalhães      11/11/09 20:38      
                                          Better to have them..      Kai Klaas      11/12/09 08:52      
                                             up the garden path      Erik Malund      11/12/09 12:24      
                                                Definitely consider min/max values from datasheet      Per Westermark      11/12/09 18:15      
                                                   Nothing more instructive than...      Kai Klaas      11/12/09 18:50      
                                                      but he won't      Erik Malund      11/13/09 07:04      
                                                         Yes, that's true...      Kai Klaas      11/13/09 08:06      
                                                            a better way      Erik Malund      11/13/09 11:40      
                                                               Datasheet      Chico Magalhães      11/13/09 12:44      
                                                                  OH BOY      Erik Malund      11/13/09 14:23      
                                                                  Logic level MOSFET...      Kai Klaas      11/13/09 15:11      
                                                                  A new test I made, bizarre...      Chico Magalhães      11/14/09 00:00      
                                                                     It seems the power supply...      Daniel Contarino      11/14/09 00:17      
                                                                     Lack of information      Per Westermark      11/14/09 03:04      
                                                                     yep. It IS very much!      Daniel Contarino      11/14/09 03:44      
                                                                        Laser and peltier      Chico Magalhães      11/14/09 07:38      
                                                                           Dont konw wich regulator you use.      Daniel Contarino      11/14/09 08:12      
                                                                              well... no regulator at all...      Chico Magalhães      11/14/09 11:09      
                                                                                 PC supplies are not very well regulated      Richard Erlacher      11/23/09 22:35      
                                                                           For 3V you should have a 3V regulator      Per Westermark      11/14/09 08:23      
                                                                     That's the explanation!      Kai Klaas      11/14/09 08:56      
                                                                        3v      Chico Magalhães      11/14/09 11:20      
                                                                           Minimum load      Per Westermark      11/14/09 11:40      
                                                                              Supply and 7805      Chico Magalhães      11/23/09 15:16      
                                                                                 you want help??      Erik Malund      11/23/09 16:35      
                                                                                    No laser Datasheet      Chico Magalhães      11/23/09 22:52      
                                                                                       then return it and DEMAND one with a datasheet      Erik Malund      11/24/09 06:28      
                                                                                          Already mentioned lack of datasheet      Per Westermark      11/24/09 06:40      
                                                                                             suggested as first step      Erik Malund      11/24/09 07:11      
                                                                                             laser      Chico Magalhães      11/24/09 07:13      
                                                                                                Hard to tell but I think you should mind the voltage      Per Westermark      11/24/09 07:40      
                                                                                 Perhaps you should use an adjustable regulator      Richard Erlacher      11/23/09 17:27      
                                                                                    I do not think so      Erik Malund      11/23/09 19:36      
                                                                                       and how would YOU build a current source?      Richard Erlacher      11/23/09 22:30      
                                                                                          line anyone else - a 'cookbook' design      Erik Malund      11/24/09 06:29      
                                                                                             can you do that without a regulated voltage source?      Richard Erlacher      11/24/09 07:16      
                                                                                                yes      Erik Malund      11/24/09 08:11      
                                                                                                   Guys, Chico has a Laser modul, already...      Kai Klaas      11/24/09 08:52      
                                                                                                      two possibilities      Erik Malund      11/24/09 09:15      
                                                                                                         assumptions are dangerous      Per Westermark      11/24/09 09:25      
                                                                                                            But I didn't assume, that it has a good current control!      Kai Klaas      11/24/09 10:32      
                                                                                                               Stable is one thing - what voltage is another      Per Westermark      11/24/09 11:50      
                                                                                                                  If only Chico had sent us a link to his Laser modul...      Kai Klaas      11/24/09 12:25      
                                                                                                                     probably highly unstable      Erik Malund      11/24/09 12:54      
                                                                                                         Yes, and a good linear regulator can supply that!      Richard Erlacher      11/24/09 22:56      
                                                                                                      That was my point!      Richard Erlacher      11/24/09 22:56      
                                                                                                      we can't know for certain, but ...      Richard Erlacher      11/25/09 23:52      
                                                                                                   What is an ST2221      Richard Erlacher      11/24/09 22:53      
                                                                                                      ST2221a != ST2221      Per Westermark      11/24/09 23:18      
                                                                                                         didn't you notice the reference to an earlier post?      Richard Erlacher      11/24/09 23:32      
                                                                                                            you will need one of these      Erik Malund      11/25/09 06:04      
                                                                                                               Yes, if you have a good, stabile supply without much noise      Richard Erlacher      11/25/09 23:46      
                                                                                                                  A current source isn't a magic beast      Per Westermark      11/26/09 02:57      
                                                                                                                     ... but only if ...      Richard Erlacher      11/26/09 15:59      
                                                                                                                        and I thought this was turkey day      Erik Malund      11/26/09 18:33      
                                                                                                                        Are you assuming CC has to be passive?      Per Westermark      11/26/09 18:52      
                                                                                                                           that would be ridiculous      Erik Malund      11/27/09 06:41      
                                                                                                                              Ask Richard.      Per Westermark      11/27/09 06:50      
                                                                                                                                 other than Richard?      Erik Malund      11/27/09 07:08      
                                                                                                                                    Now define "constant"      Richard Erlacher      11/27/09 16:22      
                                                                                                                                    Consider this ...      Richard Erlacher      11/28/09 16:02      
                                                                                                                                       Of course, it is...      Kai Klaas      11/28/09 19:30      
                                                                                                                                       Current control != Constant Current      Per Westermark      11/28/09 22:05      
                                                                                                                                       irrelevant      Erik Malund      11/30/09 08:43      
                                                                                                                                          Why do you continue in this way, Erik?      Richard Erlacher      11/30/09 16:30      
                                                                                                                                             Minimalistic const current regulator      Per Westermark      11/30/09 19:23      
                                                                                                                                                It's a matter of definition      Richard Erlacher      12/01/09 09:07      
                                                                                                                                                   Ideal constant current source...        Kai Klaas      12/01/09 09:30      
                                                                                                                                                      That's where this whole thing began ...      Richard Erlacher      12/01/09 17:28      
                                                                                                                                                         Don't jump around wildly when cornered      Per Westermark      12/01/09 23:43      
                                                                                                                                                            That's not what was said      Richard Erlacher      12/03/09 14:26      
                                                                                                                                                               That's why we should avoid to offend each other...        Kai Klaas      12/03/09 15:00      
                                                                                                                                                               Still trying to smash in open doors      Per Westermark      12/04/09 01:44      
                                                                                                                                                                  The world is flat!      Andy Neil      12/04/09 02:11      
                                                                                                                                                               VERY "poor choice of wording"      Erik Malund      12/04/09 16:17      
                                                                                                                                                                  It wasn't MY wording to which I referred, Erik      Richard Erlacher      12/05/09 09:21      
                                                                                                                                                                     Memory lapse?      Per Westermark      12/05/09 14:49      
                                                                                                                                                                        You missed the point, Per      Richard Erlacher      12/05/09 22:16      
                                                                                                                                                                     I didn't even bother ....      Erik Malund      12/05/09 18:06      
                                                                                                                                                                        Why, then did you mention it?      Richard Erlacher      12/05/09 22:18      
                                                                                                                                                                           Lots of ridiculous claims later...      Per Westermark      12/06/09 04:00      
                                                                                                                                                                              ABSOLUTELY NOT      Erik Malund      12/06/09 06:20      
                                                                                                                                                                              Cunning ?      Steve M. Taylor      12/06/09 14:14      
                                                                                                                                                                                 Perhaps, but ...      Richard Erlacher      12/07/09 10:56      
                                                                                                                                                   What definition? CC/CV both have line regulation tolerances      Per Westermark      12/01/09 09:56      
                                                                                                                                                   same old, same old, same old      Erik Malund      12/01/09 12:48      
                                                                                                                                                      There you go again ... waving your hands ...      Richard Erlacher      12/01/09 17:34      
                                                                                                                                             already answered      Erik Malund      12/01/09 12:45      
                                                                                                                                                is that what you think?      Richard Erlacher      12/01/09 17:47      
                                                                                                                                                   language, language, language      Erik Malund      12/02/09 14:42      
                                                                                                                                                      a rose by any other name ...      Richard Erlacher      12/03/09 13:44      
                                                                                                                                 nearly any linear regulator can do that      Richard Erlacher      11/27/09 14:19      
                                                                                                                              Yes, indeed      Richard Erlacher      11/27/09 12:53      
                                                                                                                                 confound it!!!      Erik Malund      11/27/09 14:21      
                                                                                                                                    Will an AC supply be adequate for you?      Richard Erlacher      11/27/09 16:21      
                                                                                                                                       that does not deserve an answer      Erik Malund      11/27/09 16:37      
                                                                                                                                          If not, then show us what is adequate!      Richard Erlacher      11/27/09 16:53      
                                                                                                                                    Now see here ...      Richard Erlacher      11/27/09 16:46      
                                                                                                   Not according to the datasheet I have ...      Richard Erlacher      11/27/09 16:29      
                                                                                                      of course it does      Erik Malund      11/27/09 16:40      
                                                                                                         So what does that schematic mean?      Richard Erlacher      11/27/09 17:09      
                                                                                                            re your babble about a constant supply voltage      Erik Malund      11/27/09 17:21      
                                                                                                               If that were the case ...      Richard Erlacher      12/02/09 19:30      
                                                                                                                  Time to return to earth.      Per Westermark      12/03/09 00:59      
                                                                                                                     What are you trying to prove?      Richard Erlacher      12/03/09 14:13      
                                                                                             Perhaps, but one with no supply?      Richard Erlacher      11/27/09 16:26      
                                                                           NOBODY, NOBODY can make this work ....      Erik Malund      11/14/09 11:53      
                                                                           How about LM317? Look it up!      Richard Erlacher      11/14/09 12:46      
                                                                           As I said here...      Kai Klaas      11/14/09 16:04      
                                    Just a minute, Chico ...      Richard Erlacher      11/11/09 23:05      
                     Double check      Daniel Contarino      11/11/09 11:34      
      I see no pullups      Erik Malund      11/11/09 06:23      
         "The commom of the resistor array is connected to +5v"      Chico Magalhães      11/11/09 08:55      
            Not what I mean!      Daniel Contarino      11/11/09 09:17      
               He probably needs pullups on both inputs and outputs.      Richard Erlacher      11/13/09 12:55      
                  be specific!!!      Erik Malund      11/13/09 14:27      
                     Now I understand ...      Richard Erlacher      11/13/09 17:33      
                        au contraire      Erik Malund      11/13/09 19:10      
   Gate Threshold Voltage, what is?      Chico Magalhães      11/26/09 05:54      
      Did you really try Google?      Per Westermark      11/26/09 06:04      
         I tried google...      Chico Magalhães      11/26/09 06:38      
            Vgs > Vgs(th)!      Kai Klaas      11/26/09 08:46      
   I GAVE UP!      Chico Magalhães      01/12/10 22:55      
      Don't give up!      Andy Neil      01/13/10 01:30      
      Yes, don't give up!      Kai Klaas      01/13/10 07:41      
      DONT GIVE UP, did you try ...      Erik Malund      01/13/10 08:17      

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