LED blinkers

Hi Guys

Could the electrickery gurus give me some info / input please ?

I've got to shift the mount point of the rear blinkers because the
ventura rack is getting in the way (it's currently bending them down at
about 30 degrees which can't be good for them, even if they are the
flexi mount ones), so I've bought a pair of LED blinkers (which I've not
fitted yet), I seem to recall however something about they flash faster
because they draw less current ? The accessories mob at Berowra were
keen to sell me a $120 "relay" to fix the issue but I figured I'd throw
it to the brains trust here first. Shouldn't I be able to just wire up
some resistors to up the current drain to slow them down - given as I
understand it the problem is the LEDs don't suck much power ?

Am I on the right track here or off the planet ? What's the best solution ?

If I need to insert resistors, do I do it inline, or parallel , and what
ohms should I get ?

Thanks.

JL

 

Of course they were: $120.00 for three dollars worth of parts
is an excellent profit margin!

It's not quite that simple. LEDs only suck a poofteenth of a microamp
of power (they'll suck more if you let them, but they won't be any
brighter).

Yes, you are. A system with appropriate voltage regulation (7805
regulator for example, Dick Smith Z6545, Jaycar ZV1505) and a 555
timer (DSE Z6145, Jaycar ZL3555) and a couple of resistors and
capacitors to get the timing you want/need would do it. I'd get
ultra high brightness LEDs and switch those with some sort of
transistor - don't let the 555 power/sink them directly, you'll
blow up the 555 in fairly short order with higher current HB LEDs.

The best solution from a safety and visibility point of view is to
fit original equipment or similar-to-OEM large incandescant light
globes/fittings/filters. The small ones simply are not visible from
more than about 12 feet away. (I had occasion to be following someone
on a bike up to Berowra a little while ago, at first I thought the
bike had no indicators, but when I got closer I realised that I
just had to watch closely at the point where I thought indicators
should be, and occasionally I'd get a glimpse of a flasher. I didn't
realise they'd be so bad, but they were, at least in this case).

If you *must* go the trendy route, use several high brightness LEDs
and pay careful attention to positioning them so that they shine
where viewers eyes should be - LEDs are quite directional with their
light output.

More complex than that 'cos, as I said, LEDs draw **** all power,
and a percentage of **** all is still **** all. A circuit to turn
the LEDs off and on as required, and an effectively seperate circuit
to deliver the right amount of power to the LEDs independant of
timing is more likely to work more proper like.


A google will likely turn up a hundred different (but all the same)
circuits. The application notes for the 555 will also turn up some
good ideas if you design from scratch. The 555 timer is the mainstay
of timing (and learning electronics) applications, and they're very
very widely used. Google for things like 555 and 'flasher',
'indicator', etc, and you'll probably find a circuit that works as
a plug-in replacement for an existing flasher can or something like
that.


If you don't find what you need and/or need help to build something,
giz a yell.


You should go the original equipment route of large/bright lights
though.


GB

 

But doesn't it already have a device turning on and off the current to
them - isn't that what the blinker can does ?

Given a choice between the same size indicators with globe and with a
dozen high intensity LED I think the LEDs should be more visible,no ?
They certainly claim to be putting out more light, and they seem
brighter to me.

Shit the ones I bought have a DOZ high brightness leds on the board.

OK, ta.

Too late !! I've already bought the aftermarket (large and extra
bright) led indicators, I just haven't fitted them yet (they're
definitely brighter than stock globes when connected to power though -
retina burning !).

I've found a couple of options that are a bit less exxy - the mob in
Castle Hill have a black box like the above mentioned one for $60,
there's also a mob in the US advertising "resistors" (could be a combo
of components in there) to be plugged inline with the blinkers for $8
US (plus P&h), there's another mob in Europe with advertised a similar
option with a heatsink (i forget the specs something like 6ohm and
50watt or something ?) for about 30 euros

and maybe a capacitor or am I dumbing it down to meet my knowledge too
far ?

I'll send you the URLs I've dug up via email, and maybe you can tell me
what I'm missing.

JL

 

www.amcmotorcycles.com sell a 'Dual Load Equaliser 01008' for LED turn
indicators for $59.40.

This is pretty easy. Take a look at the original bulb and note its
power rating. With the new LED indicator note its power or current
rating (convert current to power rating by Power = Voltage * Current).

Simply subtract the power rating of the LED indicators from the power
rating of the original bulb. Use the formula R = (V * V)/P to
determine the resistance value required.

Example
System voltage 12Vdc
Original indicator bulb power rating 25W
LED indicator current draw rating 83mA = 12 * 0.083 = ~1W

Power(resistor load) = 25W - 1W = 24W
Resistance required = (12Vdc * 12Vdc) / 24W = 6ohms

In this case you can use 2 x 22ohm and 2 x 27ohm 10W resistors in
parallel as the shunt load (resistors are about $1.50 each) - if all
are connected in series the total resistance is ~6ohms. These will get
hot so take care where they are mounted.
(Total resistance of n * parallel resistors = 1 / (1/r1 + 1/r2 + 1/rx
....+ 1/rn)

Cheers
Conrad

 

Edit - typoif
"all are connected in series the total resistance is ~6ohms" should
read
all are connected in parallel the total resistance is ~6ohms

 

You wanna know the "cheap-arsed dodgy brothers solution"?

Wire your existing incandescent globes in parallel with the bling new
led indicators, and hide the globes under the seat or somewhere...

big

 

The 'flash faster' thing is probably a warning from your bike's highly
sophistimicated relay unit that your blinker has blown. Simpler ones
tend to go slow (well, they're on for a long time then off for a short
time) when a bulb blows, instead.

Easiest thing is to replace your sophistimicated relay unit with a $10
electronic one from a servo or Kmart. You're looking for a clear plastic
can with some bits inside and two terminals.

Which wire is which on your bike depends a lot on the bike ... have
you got a wiring diagram?

You could do that if you wanted ... a 6 ohm resistor will draw 30W from
your 13.5V electrics (P = V^2/R), so putting one in parallel with each
LED indicator would do it. Bit of a wasteful approach though, and
resistors which can dissipate 30W are pretty expensive and bulky.

-----sharks

 

It's quite possible, however the bike shop fitted them not me, hmm I
must admit I didn't think of that, and I'm not sure if I got given the
instructions so I can check whether they fitted them correctly - good
thought Coney. I'll investigate it further.

Naah that's OK, any one can stuff up, and it is certainly a
possibility, however if a mistake has been made fitting it, it wasn't
mine

JL

 

Thanks very much Conrad, very helpful.

....snip
The accessories mob at Berowra were

Yeah, that's the mob at castle hill I mentioned in the other post.

OK just to confirm, all 4 resistors are wired in parallel, this gives a
resistance equivalent to 6 ohms, yes ? For the slower members of the
class, why not just use a 6 ohm resistor ?

Hmm...interesting problem of where to mount them now to deal with the
heat. A heat sink may be called for.

Thanks very much, that's brilliant.

JL

 

hehehe, I love it, that's great. Or I could go down the route of those
scooters on sunday and have the globe blinker mounted above the led
blinker, and maybe mount 2 or 3 more led blinkers on there as well

JL

 

Supercheap are selling Led clusters that have a bayonet fitting. ~$20 IIRC

Moike

 

Oooh ta ! That'll do nicely for the front blinkers (couldn't get
anything to replace them with as they're built into the mini fairing.

JL

 

Yeah manual has a wiring diagram marked up in Italish, can be very
difficult to work out but it's there.

OK, so step one is to fit them and see whether I have a sophistimacated
relay or a low rent one, if they haven't fitted a cheap arse one, go
source one from Kmart and see if that fixes it. If it doesn't then
pursue other routes re resistors already discussed.

Kewl, we have a plan !

JL

 

Yes - wire all resistors in parallel and then connect them up in
parallel to the LED. If you can find a 30W 6ohm resistor then you can
just use one - else you need to use a bunch of 10W resistors in
parallel to stop them from reaching infinite resistance as all the
smoke escapes.

I wouldn't bother with a heatsink, resistors can take the heat, maybe
just mount them with some space between them on some ally plate and
then to the frame - I was more concerned if they are touching things
that will melt or burn.

Using the original bulb as the parallel load is a great idea. Also
lets you go for the undercarriage illumination look option like some of
the boyracer cars The LED units don't tend to draw much current so
the flash rate should be about the same.

Cheers
Conrad

 

Ooh good thing I checked, I would have wired the cluster of resistors
in series before the blinker (proving once again a little knowledge is
a dangerous thing). Thanks.

Ahhh light dawns on marble head ! Of course you've got to get the
wattage right. Obvious when someone points it out...

OK, no worries.

Hehehe yeah pass. I'd have just relocated the original blinkers except
they're the "generic square bike rear blinkers" and they look out of
place on the bike, the new ones look a bit nicer.

JL

 

Feel free to scan and email (yeah, that's a real address) if you'd
like some advice on it ... but in general[*] you're looking for a
circuit something like (bad ascii art follows):

Battery+
|
Fuse Box
|
Ignition switch
|
Flasher Can
|
Indicator Switch
| |
Left Inds Right Inds
| |
ground

.... the side from the ignition switch is then the positive
side, and the side to the indicator switch the negative side.
Some flasher relays also have a (third) ground terminal.

Yep.

-----sharks

[*] Eg: not on BMWs.

 

wrote in

Not that you're not incompetant or anything <grin>!

Had a bit more of a thunk about this on the way back from the
bottle-o with a case of beer on the tank tonight, and thunk to
myself that somewhere way back when I'd read about an alernative
magic flasher can that doesn't suck.

(Bear in mind that they generally dumb-down things in 'hobbyist
electronics' magazines to a level where even blind freddy can
get pretty worked up about the level of 'technology' that isn't
displayed therein!)

Generic 'mechanical' flasher cans rely on a certain amount of
current being drawn for a given, er, rate-of-flash. Suck less,
flash more, and vice-versa.

I do remember reading various articles in electronics magazines
with circuits that offer 'current independant' flasher cans.
Assorted 'kits' from DSE and Jaycar and Altronics are likely
available, and I'll build it for you if required. the new cans
should work (as in give an acceptable rate-of-flash) regardless
of what the load is. Should take a whole crapload less of effort
than many of the afore-discussed solutions.

HTH, HAND, WTF, OMFG, GAGF, LOL,

GB

 

remember that they're directional though John, if the LED 'bulbs' are facing
forward, you'll be fine, if they are mounted sideways thats where the light
will be going.

Al

 

yer...wot he said

use wire wound resistors

try it first tho...there may already be compensation built in...measure
it with yer meter...without will be about 330 ohms

if not the extra resistor(s) will go across the load so it draws the
same as a bulb

also...it's not really that critical, a 10 ohm 10W resistor should do
the trick

 

also...it's not really that critical, a 10 ohm 10W resistor should do

cos;

original current draw = 12/8 ish = ~1.5A

12/10 = 1.2A...close enough, + a bit for the LED lamp

10W cos 10 ohms at 12V is only 14.5W and its not on 100% duty cycle so
it'll have time to cool down a bit!