Timeline for Timed LED circuit with ATX PSU, help
Current License: CC BY-SA 3.0
9 events
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| Jul 27, 2014 at 15:05 | comment | added | George Herold | @NeddThehead, OK I've gotta run soon anyway. Do you have a DMM, 'scope or other test equipment? I suggest you make the lm317 current source (maybe low current at first, 1-10mA) and hook up some resistors and see how it works. V=IR and all that. | |
| Jul 27, 2014 at 14:56 | comment | added | NeddThehead | Not enough reputation. :/ | |
| Jul 27, 2014 at 14:38 | comment | added | NeddThehead | Yeah, sure. (I guess I'll delete this when you've read it). | |
| Jul 27, 2014 at 14:27 | comment | added | NeddThehead | So if I understand it right there will always be a circuit compensating for the voltage and current changes that must accur, because neither of them can be truly constant while the other is variable? Something is just making an output thats constant in both voltage and current? Eg. voltage always changes with current and resistance according to Kirchhoff's laws (except eg. AC circuits)? Why is it even called a current source if the voltage of the output also must be constant to deliver/draw that current? Sorry for all the questions, but I think I'm confusing myself with these questions. | |
| Jul 27, 2014 at 14:17 | comment | added | George Herold | Well a current source keeps the current constant for any load. (up to it maximum voltage which is called the compliance voltage of the current source, the converse of the maximum current that a voltage source can output.) A current source is "happiest" when it's driving a small impedance, and a voltage source is "happiest" driving a large impedance. | |
| Jul 27, 2014 at 14:09 | comment | added | NeddThehead | That's what I thought, but when this "current source" and non-linear current characteristics came about I kinda got a bit confused. I always thought that no matter what, you couldn't change the current itself, just voltage, which then directly affected current. "Current limitating" and "current source" is really confusing. I think I'll ask this in it's own question. | |
| Jul 26, 2014 at 20:41 | comment | added | NeddThehead | Nice part indeed. :) But my power supply is a current source for that exact voltage since it's a switched-mode type, or is it not? And a regular (linear?) power supply is not a current source? | |
| Jul 25, 2014 at 21:48 | comment | added | NeddThehead | Thanks! I thought that this power supply was a "current source" itself, as it is a switched-mode PSU (maybe I misunderstood it). But I either way need to lower the voltage. The LM317 looks great for this use. :) Then I'll add those to the list. I'll get back to this tomorrow. | |
| Jul 25, 2014 at 21:39 | history | answered | George Herold | CC BY-SA 3.0 |