| 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 |
| Topic | Author | Date |
| 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 |



