Calling All 'Lectronicians !
in [Harley-Davidson]
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From: spacecriter (Bill C) on 8 Jun 2010 07:04 Snag wrote: > Windstream wrote: >> Okay, each LED draws about 20ma of current and needs 2 volts. You >> need to use a resistor to drop the voltage down 10 volts. > > Nope , they make solid state regulator units . Got two of 'em on the > PCB of the DRO I built from a kit . One does +1.5v for chinese scales > , the other +5v for quadrature scales > >> 40 bulbs, >> wired in parallel, at 20ma each comes to 800ma. > > Lessee here , current is common in series , volts in parallet . So > I'm going to be pulling 20 ma per string of 5 LED's , and 8 strings > for brakes . Sounds more like 160 ma ... and 20 ma for tail lights . > Snag, I agree with you on the parallel/series part. However, you don't have to use a voltage regulator in this application. Another solution is to put in a current limiting resistor. That is, use the resistor in series with the LEDs to drop the voltage down to 10 volts. Pick the highest current you want through the LED and use this calculator to pick a value. http://www.quickar.com/noqbestledcalc.htm I don't believe you need to use one R per string, but I would use more than one for the whole circuit. Maybe one R per 3 strings? Just a guess on my part. Remember, the more strings conneted through one R drives more current through the resistor, and it will have to be rated for more power dissipation. Also, you may want to put in a ceramic capacitor around the whole thing (paralle to all of it) to cut down voltage spikes (ignition noise). -- Bill C. "I am NOT lost... I'm *exploring*"
From: Snag on 8 Jun 2010 07:27 Old Crow wrote: > "Snag" <snag_one(a)comcast.net> wrote in message > news:0qfPn.140038$0M5.112264(a)newsfe07.iad... >> I've had comp er comments about my brake lights not being bright >> enough ... so I thought I'd try my hand at fabricating an LED unit . >> Wow , those things want a really narrow range of voltages ! So I've >> got a hundred (less 7 , how do ya think I found out how finicky they >> are ?) of these wide angle "top hat" red LED's that want between 1.8 >> and 2.2 volts, and I wanna use them to make a light panel to go in >> my tourpak lid . Actually, to replace the bulb that's in the fixture >> now . I'm thinkin' (see the steam ?) that I can use a voltage >> regulator to drop the supply volts to 10 and wire them in series >> ckts of 5 each , for a nominal voltage drop of 2 volts each . I'll >> need 2 regs if I want to do taillight too ... it'll have to be >> breadboarded inside the fixture , but there's plenty of room in >> there . Insights , oversights , am I crazy for wanting to do this ? >> I'll probably run about 40 bulbs (@20 ma/ea , IIRC) for brake and 10 >> for runnin' lights , reckon I'll need a heatsink for the brakes ? >> -- >> Snag >> "90 FLHTCU "Strider" >> '39 WLDD "PopCycle" >> BS 132/SENS/DOF >> > > > I noticed Sat when we followed you to lunch that you either weren't > using your turn signals, or they aren't very bright either. Have you > checked the grounds back to the lights? Even Dave's tail light is > brighter than yours. > -- > Old Crow > '82 FLTC(P) 92" > '87 FLTC > '61 F-100 302/C-6 > BS#133, SENS, TOMKAT, SLOB#13, MAMBM They were not operable ... something that I thought was in the bar control pod , but turns out it is more likely in the module inside the fairing , or in the wiring to it . I juggled that module around while installing the new cable . Had that damn control apart 3 times yesterday tryin' to figger it out . Then when I wiggled the module they came back ... Oh , and the brake light wasn't working from the front because the solder connection broke , once I got that soldered back on it was OK . I've checked , and there is zero voltage drop to ground when I turn the lights on , the problem is in the supply wiring - the voltage drops when I hit the lights , just like it does on the dash voltmeter . I suspect there's a dirty/bad connection in one or more of the plugs in the harness , most likely in the ignition switch wiring - because I've checked almost all the rest . Fairing has to come apart to get at those connectors , and I just haven't felt up to tackling that yet . -- Snag "90 FLHTCU "Strider" '39 WLDD "PopCycle" BS 132/SENS/DOF
From: 73Sportster on 8 Jun 2010 07:56 "spacecriter \(Bill C\)" <spacecriter(a)sysmatrix.net.yercrank> wrote in news:zp6dnR-z-7RbvpPRnZ2dnUVZ_sKdnZ2d(a)sysmatrix.net: <a buncha stuff that I snipped> Wanted to let you know that ya'll were missed this weekend. Talked about you too! That's what you get for not showing up. Rosie, tell the missus I said "Hi!"
From: spacecriter (Bill C) on 8 Jun 2010 20:01 73Sportster wrote: > "spacecriter \(Bill C\)" <spacecriter(a)sysmatrix.net.yercrank> wrote in > news:zp6dnR-z-7RbvpPRnZ2dnUVZ_sKdnZ2d(a)sysmatrix.net: > > <a buncha stuff that I snipped> > > Wanted to let you know that ya'll were missed this weekend. Talked > about you too! That's what you get for not showing up. > > Rosie, tell the missus I said "Hi!" heh, shoulda known...Was wondering why my ears were ringin' Missed all you folks too. I bet nobody had any fun either <g> Don't know if you saw my post across the street, but one of our cabana boys was graduating Saturday. We now have a Dentist in the family woo hoo! I'll tell Lisa "Hi" for you if you'll pass along my "howdy" to Kenny. -- Bill C. "I am NOT lost... I'm *exploring*"
From: Old Crow on 9 Jun 2010 05:48
"Snag" <snag_one(a)comcast.net> wrote in message news:3PpPn.46280$Ak3.32180(a)newsfe16.iad... > Old Crow wrote: >> "Snag" <snag_one(a)comcast.net> wrote in message >> news:0qfPn.140038$0M5.112264(a)newsfe07.iad... >>> I've had comp er comments about my brake lights not being bright >>> enough ... so I thought I'd try my hand at fabricating an LED unit . >>> Wow , those things want a really narrow range of voltages ! So I've >>> got a hundred (less 7 , how do ya think I found out how finicky they >>> are ?) of these wide angle "top hat" red LED's that want between 1.8 >>> and 2.2 volts, and I wanna use them to make a light panel to go in >>> my tourpak lid . Actually, to replace the bulb that's in the fixture >>> now . I'm thinkin' (see the steam ?) that I can use a voltage >>> regulator to drop the supply volts to 10 and wire them in series >>> ckts of 5 each , for a nominal voltage drop of 2 volts each . I'll >>> need 2 regs if I want to do taillight too ... it'll have to be >>> breadboarded inside the fixture , but there's plenty of room in >>> there . Insights , oversights , am I crazy for wanting to do this ? >>> I'll probably run about 40 bulbs (@20 ma/ea , IIRC) for brake and 10 >>> for runnin' lights , reckon I'll need a heatsink for the brakes ? >>> -- >>> Snag >>> "90 FLHTCU "Strider" >>> '39 WLDD "PopCycle" >>> BS 132/SENS/DOF >>> >> >> >> I noticed Sat when we followed you to lunch that you either weren't >> using your turn signals, or they aren't very bright either. Have you >> checked the grounds back to the lights? Even Dave's tail light is >> brighter than yours. >> -- >> Old Crow >> '82 FLTC(P) 92" >> '87 FLTC >> '61 F-100 302/C-6 >> BS#133, SENS, TOMKAT, SLOB#13, MAMBM > > They were not operable ... something that I thought was in the bar control > pod , but turns out it is more likely in the module inside the fairing , > or in the wiring to it . I juggled that module around while installing the > new cable . Had that damn control apart 3 times yesterday tryin' to figger > it out . Then when I wiggled the module they came back ... Oh , and the > brake light wasn't working from the front because the solder connection > broke , once I got that soldered back on it was OK . > I've checked , and there is zero voltage drop to ground when I turn the > lights on , the problem is in the supply wiring - the voltage drops when I > hit the lights , just like it does on the dash voltmeter . I suspect > there's a dirty/bad connection in one or more of the plugs in the harness > , most likely in the ignition switch wiring - because I've checked almost > all the rest . Fairing has to come apart to get at those connectors , and > I just haven't felt up to tackling that yet . > -- > Snag > "90 FLHTCU "Strider" > '39 WLDD "PopCycle" > BS 132/SENS/DOF > Yeah, but living where you do, I'd fix it soon. Might try some 2057 bulbs in the taillight. Made mine brighter. -- Old Crow '82 FLTC(P) 92" '87 FLTC '61 F-100 302/C-6 BS#133, SENS, TOMKAT, SLOB#13, MAMBM |