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| Thread ID: 116907 | 2011-03-25 02:13:00 | 'Technical' But NOT About Puters! | SurferJoe46 (51) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1189250 | 2011-03-25 02:13:00 | . . . so I put it in the 'GENERAL-CHAT' area . . . . here goes . . . . . . . . . . . . . . I need a brainy person to tell me what I'm doing wrong - but I don't want to admit the sheer number of failures I've had so far (NO - this is NOT a LINUX installation!) I would really appreciate it if SOMEONE can give me the right resistor values for running LEDs in my dashboard (NZ = head stopper) lights instead of incandescent bulbs . I can and have worked out the physical mounting of them - they just burn out in a few days and this is getting tiresome . The voltage I am dealing with is at a MAX = 14 . 2 VDC, and the lower voltages are somewhere near 10 . 5 VDC if I should crank (NZ = spin) the engine (NZ = powerplant) with the lights still ON (NZ = lit) . Any takers on this electrical voyage with me? |
SurferJoe46 (51) | ||
| 1189251 | 2011-03-25 03:15:00 | If I recall my physics at Uni, it appears Ohms law, either in series or parallel, (V= IR need be applied). But I think you need to calculate/know current, and LED voltage/supply voltage difference to apply Ohm's law. See example for Rover dashboard (forums.mg-rover.org) and power/current formula (www.sengpielaudio.com) |
kahawai chaser (3545) | ||
| 1189252 | 2011-03-25 03:30:00 | Are the leds for illuminating the gauges in the instrument panel | prefect (6291) | ||
| 1189253 | 2011-03-25 03:45:00 | I've found this led.linear1.org Seems to be what you're looking for. I think normal 5mm LEDs are 3V usually, so you need a resistor that will drop the voltage going through the LED to around that. |
ryanjames.powell (13554) | ||
| 1189254 | 2011-03-25 03:54:00 | If I recall my physics at Uni, it appears Ohms law, either in series or parallel, (V= IR need be applied). But I think you need to calculate/know current, and LED voltage/supply voltage difference to apply Ohm's law. See example for Rover dashboard (forums.mg-rover.org) and power/current formula (www.sengpielaudio.com) Isn't ROVER a LUCAS thing-y? Are the leds for illuminating the gauges in the instrument panel Yes. I've found this led.linear1.org Seems to be what you're looking for. I think normal 5mm LEDs are 3V usually, so you need a resistor that will drop the voltage going through the LED to around that. OK youse guys. I will buy some MORE LEDs for the dashboard and then we can all sit down together with the various values and try to plug them in and see if they all go POOF again or not. They aren't very expensive by a long shot - and I surely like the brightness of them - at least for a few moments. Here's my thought: I believe (unless corrected by youse) that running them in parallel is better than in series since they individually have a somewhat broader tolerance to voltages that peak and null in a vehicle voltage system - and wired in series they may be collectively less tolerant of surges or changes that are inherent with a car electrical system. I know the current draw of them is infinitely small, so I was gonna try a linear taper 500KΩ potentiometer to see if I could get them to work for longer that a night or two. Make that ONE, SHORT night. |
SurferJoe46 (51) | ||
| 1189255 | 2011-03-25 04:01:00 | First of all SJ ... go have a look at this site .... www.chemistry.co.nz ... :D | SP8's (9836) | ||
| 1189256 | 2011-03-25 04:06:00 | Hey - I just like twistin' tails a little. I know youse guys almost speak English - but some of the words are - well, never mind. I also watch Top Gear trying to understand UK: mylipsaren'tmoving-speak. |
SurferJoe46 (51) | ||
| 1189257 | 2011-03-25 05:42:00 | The only advice I can give is: Get the polarity on all of them right. Otherwise, consider the rest of this a very amateur opinion. Wiring in series means if one blows they all go out. Wiring in parallell means if one blows the others stay lit. I believe LED brightness is typically adjusted by the rate at which power is pulsed to them, rather than by adjusting volts / amps. Dunno if they'd like a circuit with a restor style dimmer. Starter motor drain can do very strange things to other circuits. Dunno, but you may need to consider some inbuilt protection in this regard. Maybe even a small relay to cut the power to the LEDs when the starter is engaged. |
Paul.Cov (425) | ||
| 1189258 | 2011-03-25 06:07:00 | The only advice I can give is: Get the polarity on all of them right . Otherwise, consider the rest of this a very amateur opinion . Wiring in series means if one blows they all go out . Wiring in parallell means if one blows the others stay lit . I believe LED brightness is typically adjusted by the rate at which power is pulsed to them, rather than by adjusting volts / amps . Dunno if they'd like a circuit with a restor style dimmer . Starter motor drain can do very strange things to other circuits . Dunno, but you may need to consider some inbuilt protection in this regard . Maybe even a small relay to cut the power to the LEDs when the starter is engaged . That's kinda what I thought too . The relay is a very good idea for cranking time . I wasn't thinking so much about a dimmer resistor - as I was just going to try for the best voltage to get them lit and read the value and solve for the resistor I needed from there . It might take a few kamikaze volunteer LEDs to get the voltage right though . Trial and error is fun . Smoke in colors is not . |
SurferJoe46 (51) | ||
| 1189259 | 2011-03-25 09:11:00 | Try 1/4W 820 ohm for a single LED across the battery. Ground >---0---/\/\/\---> positive supply, "0" represents an LED, colour (or color) it in manually to suit your application Better is to put 3 LEDs in series plus a series 1/8W 220 ohm resistor, not so much heat wasted. So, Ground >--0---0---0---/\/\/\---> positive supply. Avoid anything from Rover, Lucas or any other Eurotrash. Leave the LED out to simulate their efforts. |
R2x1 (4628) | ||
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