Question for the LED knowlageable

[POPEYE]

on a diff note can i pop down saturday,lunchtime ish to pick up?on way thru to rods?if so can u pm addy,many thanks!

Course you can Andy i'll pm ya in a minuite

[POPEYE]

Nowt like being awkward.

Tail lights 12V ---|diode|--|resistor|--[BL connection point]--|resistor|--|L.E.D's


Brake lights 12V ---|diode|-----[connected to BL connection point]


That should do the business with a single bank. Both resistors would want to be around 1K, or possibly slightly less. I think 560ohm is about the lowest safe value. I think I used 680ohm on my L.E.D's.

Yup!! i'm awkward Matt!! sorry Diode's thats the thingy's, i thought there was summat that only allowed current one way, and after a quick google i feel much better i think it's general purpose diode's i want, (there are so many) i have to go to maplins tomorrow for some heatshrink so it may be worth while asking there (or am i being silly)
I was confused when you say you used 680ohm resistors! the ones i got with most of the leds i've bought are 470ohm, mostly ultra bright's, dont know if you remember but you sent me a pack of resistors, they are 620's and i had a play with em last night, hooked up to a blue ultra bright i got a very dim light, to a red, no light at all and same with a red defused (which you also sent me,) so 620 seems to high to me, let alone 680, or am i missing, something,

[MattF]

I was working on standard L.E.D's. Ultra types have a higher current requirement, so drop the resistor values accordingly. If the L.E.D goes pop, you know you went too low. Diode wise, 1N400* series will do the job nicely. They are pretty much a cover all. 1N4001's should be ample for 12V, but just get whichever they have in stock if they don't have those. (They are the most common power diode though, so they should have some of that range in stock, even at Maplin's). The final number only denotes the max voltage it can cope with, so any of the 400* series is fine. Remember that the silver/white band goes at the resistor end, not the 12V supply end.

[POPEYE]

Cheer's Matt, thats all noted, this is all at the planning stage as i first need to find suitable encloseures for em, or make some, more looking round B&Q and hardware shops, once i have a few led's and selection of resistors/diode's etc i'll have a play around with a small array till i find the best option and just multiply that set up to suit the bar(s),
Thanks again mate

[Vultch]

Not at all sure i'm with ya on this but i think any way you connected your feed and neg would only light some of them where ever you connected it, not sure tho, i think all anodes have to connect to anodes and cathodes to cathodes when in paralel, series its like a daisy chain, cathode to anode and so on with a + &- each end,
i was thinking if i connect a line of leds in paralell feed through high value resistors to reduce their brightness this would give me tail lights, then if i could feed then with higher voltage (lower value resistors) they would go brighter giveing me break lights, only thing wrong with this that i can see is the current from tail lights circuit would feed back through the low value resistors causeing the break light to come on (all of em) as current flows through a resistor both ways, think it'll be easier to go matts way and have two seperate circuits,
my head hurts now

Put a diode in each circuit. ( a diode is a one way valve for elecy) they are cheap and small

[POPEYE]

Cheer's Vulch, matt suggested the same thing, got half a doz to pratice with from maplitz, only 66p

[gnash13]

LED help

i found this last week, let us know if its what your after , am planning on using it myself.

http://www.myra-simon.com/bike/LEDlight.html

have a look at this link.

good luck

[POPEYE]

Cheer's Nick, looks interesting, just printed it so i can have a good read, the parts list is very handy!

[SURFerRob]

It seems you blokes are trying to re-invent the led tail light

check this out..
http://www.narva.com.au/LEDLighting_22.html

[MattF]

It seems you blokes are trying to re-invent the led tail light

Not reinvent. Merely make ones own. Some of us do still prefer to make our own equipment where possible and practical.

[POPEYE]

Not reinvent. Merely make ones own. Some of us do still prefer to make our own equipment where possible and practical.

Well said matt, where's the fun in just buying what you want when you can spend twice as much and get a week of sleepless nights as well

[MattF]

Well said matt, where's the fun in just buying what you want when you can spend twice as much and get a week of sleepless nights as well

Ah, how true.

[SURFerRob]

I can see where you blokes are coming from... gotta get in the shed away from the missus and kids.... BUT... dont worry... point taken...

why not only light up say 1/4 of the lights for tail light duty and then ALL of em for brakes...

How many LED's are you going to use? if you were to use a 6x6 grid and light up the outside ones only for tail lighting and ALL 36 for brakes..... just a thought...

[Robmatthews]

just to make it a little more confusing you need to take into account two main things leds ARE affected by temperature change and you need to reduce your forward current as the temperature rises,if you dont it goes POP.2nd you need to take into account the varying voltages from 12 volts(ish) with engine off and 13.9(ish) volts when engine running as this affects the current, see below on an example of led that is 3.4 volt rated

3.4 volts LEDs will Draw:
3mA @ 12 volts
10mA @ 13 volts
20mA @ 14 volts
30mA @ 15 volts
40mA @ 16 volts
But four 3.2 volt LEDs will draw 50mA at 16 volts. Four 3.6 volt LEDs will draw only 0.8mA at 12 volts.

[POPEYE]

Still aint got round to trying these out yet, being a bit borasic i have'nt ordered the leds yet, so not sure what rateing the leds will be, probably i'll do what i always do and use a resistor for each one, mega fafing about but i'll at least know their covered,
not a bad idea Rob, i dont know how many i'll be useing till i find a suitable caseing to stick em in, but i'm hopeing for about 4 deep X just under the width (or lenght i should perhaps say) of the bumper,