led flasher connection

[cwah]

hello there,

I received recently my led flasher but there was no instruction at all on the wiring:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300697693259#ht_2874wt_1396

Does anyone has an idea on what these numberes mean to make my hobbyking led flash?

 

[Ricky_nz]

Heres a link to a datasheet of a similar device. likley same pinout. It gives a wiring diagram.
http://ledstuff.co.nz/datasheets/LED-RLY02.pdf
Its not the best diagram but it might give you some clues.
Also make sure you waterproof everything well because these flasher units for LEDS start switching when the connections get even slightly damp due to being designed for low current.

Edit: pretty sure this is the correct datasheet as its identical to the first google hit for the CF13JL02 unit shown in the linked auction.

 

[cwah]

Ok, going to try that. Thanks

 

[cwah]

Receive this picture from the ebay seller:

So the + of the led on the 'L' and the ground to the '-IE'?

 

[Ricky_nz]

So the + of the led on the 'L' and the ground to the '-IE'?

Yes, matches the circuit from the datasheet I linked with similar names, although the datasheet is wrong and shows diodes reverse polarity.
+12V to BI
0V(GND) to -IE
LED+ connected to L
LED- to GND.

 

[cwah]

That's great. Can safely plug it then.

Thanks Ricky

 

[cwah]

So the + of the led on the 'L' and the ground to the '-IE'?

Yes, matches the circuit from the datasheet I linked with similar names, although the datasheet is wrong and shows diodes reverse polarity.
+12V to BI
0V(GND) to -IE
LED+ connected to L
LED- to GND.

hmm.. tried this combination, it doesn't work

 

[Ricky_nz]

What LEDs were you using? I think these need a minimum current to start switching but it is pretty low like 20mA.
On my bike I'm using motercycle arrow indicators front and rear and I think they draw a coupleof hundred mA on the one I have.
I believe its a pretty standard pinout so not sure what else is wrong.

I'm assuming the one you brought is rated for driving LEDs. if not it might require amps to start switching.

To eliminate variables you could replace the LEDs with a brake light bulb for a test.
If I remember I will check my wiring tonight.

Edit: Just reread your using a hobbyking LED. That might not be drawing enough current at 12V to start the unit flashing.

 

[cwah]

Hmmm.. Thanks ricky.

So I either have to change the flasher to something that have higher amps and change my leds?

 

[NeilP]

That is standard flasher pinout numbers

ignore the hazard bit
49 positive
31 ground
49a to the switch

any automotive store should have a selection, you want an electronic one and not a mechanical one for LED's as the mechanical ones will not work with low current LED's as I think you have found.
They tend to be rated as for the current or wattage of the lamps in use. You may find you need to put a low value resistor across the LED to draw some more current to cause the flasher unit to work.

 

[cwah]

You mean I go to a n automotive shop and buy a new led flasher?

 

[NeilP]

yes, why not...
the issue will be finding someone in the store that is actually knowledgable and not just a 'salesperson'.
Trouble is that most places can only find parts by knowing vehicle make and model number type info..they know absolutely nothing about the parts they are selling. it is just a part to them that fits one model of car/motorbike etc

I suggest googling around a bit to find spec of various units and then get a part number from a manufacturer.

Going in with a spec is almost useless

or build something your self.

parts are going to be cheap so you can afford to experiment

http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html

 

[NeilP]

Either build your own that you can change the flash rate yourself, as per this instructables
http://www.instructables.com/id/LED-Flasher-automotive-or-motorcycle/

Or as I said earlier, a resistor maybe the answer..they sell them specifically on ebay

http://www.ebay.co.uk/itm/LED-bulb-turn-signal-blinker-flasher-fix-load-resistor-/310112444051?pt=UK_Motorcycle_Parts&hash=item4834245e93#ht_500wt_1243

 

[cwah]

Hmm.. going to an automotive shop won't probably get much result. Most of the time when I try to find any knowledgeable seller they are actually not.

So if I buy this resistor and plug it in series between the led and the flasher, it should work?

 

[NeilP]

Hmm.. going to an automotive shop won't probably get much result. Most of the time when I try to find any knowledgeable seller they are actually not.

Yep that is as I said earlier

So if I buy this resistor and plug it in series between the led and the flasher, it should work?

think it goes in parallel, to pass extra current 'around the side' of the LED

 

[cwah]

Thanks Neil. Going to buy the resistor then

 

[NeilP]

I am sure for a trial it does not need to be a big heat sink finned one like that..OK for constant use, yes, to save it burning out, but to test out the theory, you need to know what the actual value the flasher you have is designed for,
As the e-bay advert says,,that value resistor is OK for a system designed for 12volt 21 Watt bulbs.
Assuming two bulbs in the original system, that would be 42 watt
P=IV
42 = I x 12
so current = 42/12 = 3.5 amp current through the the relay flasher, and this is what the resistor must draw to make that flasher unit work

V=IR
or in this case R=V/I = 12 /3.5 =3.4 so I reckon that resistor they are selling is a 3.4 Ohm resistor rated at 50 Watt

But that resistor is only suitable for a flasher that was designed for those particular wattage bulbs.

Need to know what value YOUR actual flasher unit was designed for.

if you do not know, then I suggest finding a variable resistor (potentiometer) of probably ...umm I don't know...say 47 Ohm..something liek that.
put that across the LED, and with it started at max resistance, slowly reduce resistance till the flasher unit starts flashing...
if it is a low power pot, then it probably will get hot quickly, as I could be drawing a lot of current, 2 , 3 4 amps...till it burns up..So so not leave it running. Just see that the flasher works and flashes the LED.
Stop then measure the resistance of the pot and ONLY then buy a resistor of a suitable value.
Of if you have old scrap PSU's kicking around,scavenge old resistors off them,and parallel up as many as needed to get resistance down so the flasher works

 

[NeilP]

I just re read your first post..You state it is an LED flasher..so if it is designed for LED's then using the resistor that was designed for a bulb system will probably be a bad idea. I am only guessing buyt it may well draw too much current and may damage the flasher.
if you are going to try a resistor, i would now have to suggest going with something of much higher resistance..Maybe start with a 5kpot across the LED and see what happens as you reduce its value.
Remember I am not EE, I am just telling you what I would do to try and get it all working

 

[Ricky_nz]

I just re read your first post..You state it is an LED flasher..so if it is designed for LED's then using the resistor that was designed for a bulb system will probably be a bad idea. I am only guessing buyt it may well draw too much current and may damage the flasher.
if you are going to try a resistor, i would now have to suggest going with something of much higher resistance..Maybe start with a 5kpot across the LED and see what happens as you reduce its value.
Remember I am not EE, I am just telling you what I would do to try and get it all working

It shouldn't need too much current through a resistor. it appears to be similar to the one I used in that the ebay page states 12V, 0.02-20A. That means as long as your LED draws 20mA it should work but it could be used in the place of a normal flasher as well.

Have you measured the current the LED draws when connected directly to your 12V supply (Assuming the led has a dropper resistor included in its wiring)? If its less that 20mA you would need a resistor in parallel that can bring it just above that level.

For 20mA through the resistor:
R =V/I = 12V / 0.02A = 600R
P = I^2R = 0.02^2*600 = 0.24W
The resistor wouldn't be too critical. Go a little lower in value to be sure. maybe a 560R

 

[cwah]

Thanks. Going to check how much current my led is drawing.

NeilP, thanks for your suggestion. It's better to try something rather than not doing anything

 

[NeilP]

good luck

 

[Sacman]

All the info NeilP has said regarding using an automotive flasher and increasing/decreasing resistanc is generally correct. You can use it to flash any circuit load (LED lights, halogen lights, horns, etc.) I used to install car alarms over 20 years ago and using an automotive flasher is something regularly done by car stereo install shops. You can use a standard automotive flasher or a flasher that is microprocessor controlled.

The standard automotive flasher (like the ones used for turn signals) has a flash rate that is dependent on the circuit load (resistance). It has a heating filament inside that heats up and cools down at a cyclic rate of about half a second. This flasher is initially NC (normally closed) and when you hook it up to a load the filament heats up and after half a second the circuit OPENS. While open the filament will cool down after another half second and CLOSE the circuit ... hence the flashing cycle. If you place it in series with a lower resistive load it will flash faster. Conversely, it will flash slower if you put it in a higher resistive load. Don't get the "heavy duty" flashers because it will take a long time to heat the filament and you'll get a very slow flash rate. You will need to know the resistance of your LEDs and add the appropriate resistor in series with it to get the desired flash rate.

You can also use the solid-state flashers that many alarm install shops carry. They are about 3 or 4 times the cost of a standard automotive flasher but they have adjustable flash rates and some have built-in relays to flash a circuit that has higher current draw (like the air compressor of an air horn).

 

[cwah]

Thanks Sacman et Neilp

I also think that Neilp is very knowledgeable. What I mean is that even if he may not be completely sure, it's always best to try.

How do I measure the resistance of my led?

 

[Ricky_nz]

How do I measure the resistance of my led?

You don't need to measure the resistance of your LED and its not directly measurable with a meter.
If your LED came pre-wired to run off 12V then it will have a resistor in series with it but you don't
need to care about its value either. If your LED didn't come pre-wired for 12V then I would guess it would be dead by now. If the LED came prewired for another voltage then you would likely need to add some resistance to reduce the current to safe levels to run off 12V.

If you measure the current it draws at 12V with a multimeter you can calculate its effective resistance using ohms law by dividing 12V by the number of amps to get ohms. You might even be able to look on the hobbyking site and find out how much current it is intended to draw at 12V.

The auction said it was for an LED flasher so it should be electronic but they still have effectively a relay internally or at least the one I have does as I can hear it clicking.
Since the flasher has a rated current range it should be good enough to just know the current your LED draws at 12V.

 

[cwah]

On hobbyking it was written 400mA current draw. On eBay the flasher works from 0.02A to 20A, so it should be ok?

ps: I can also use my multimeter to measure the current draw. I suppose I just plug it in parallel with the light and turn the multimeter to amps measure.