Car flicker unit ...

[wee wee]

Hi guys,

Just a little question for general knowledge ...

In a car flicker unit for normal bulb, the blinking action is triggered by the bulb drawing amps.... if i got that right. So if you plug that same unit on a led light the led will just stay on because of the low amp usage.

My question is, is it possible to fit this unit on a led by "cheating" with the amp consomation, I was thinking of if we put a resistor in parallel to the led? will it make it blink ?

Thanx

Cheerz

[stj]

Re: Car flicker unit ...

not always.

there are 3 types of flasher relay.

the oldest type used a bi-metal strip with a heater on it, the current used by the bulbs heated the strip and cut the power, then it cooled and turned on again.
and so-on.
those are designed for a specific wattage and have problems with bad lamps or trailers.

the newer type are electronic and the speed is fixed.

a few of the very newest actually mess with the speed to indicate lamp failure - those are a pain.
there is a thread here where a guy fucked one trying to fool it.
show us the relay you have.

[wee wee]

Re: Car flicker unit ...

Hi STJ,

I have got those two relay;

FR-109
Flasher (mine is electronic brand but look the exact same)
2P, 32CP, MA x 20
12V

and FR-113
Flasher
552
2P, 32CPmax. 6
12V

Ref. http://www.allproducts.com/traffic/maiding/p11.html
http://www.allproducts.com/traffic/maiding/p11-l.jpg

What do you think?

[stj]

Re: Car flicker unit ...

looks like it may be the old thermal type.

put the led bulbs in and see if it works.

[Longbow]

Re: Car flicker unit ...

Maybe a 4th type. Modern cars have a "bulb out" indication on the dash. The ECU looks for some expected current draw, and if the current is below what the bulb is rated for, your bulb out indicator comes on. A good place to get automotive led replacement units is superbrightleds.com. They will sell you a bleeder resistor that will keep your bulb out indicator from tripping when you install an led. But of course that defeats the purpose of using an led in the first place.

[stj]

Re: Car flicker unit ...

if he has a thermal flasher, he'll need 20w resistors!!!!!
for each bulb!!!!!!!!

[wee wee]

Re: Car flicker unit ...

I tried with a 12v 10w bulb witch triggered the unit only once ... think the bulb is too week but don't have a bigger one.

So if I get it right I must put a resistor of 40w since the unit is for two led at the time (+the one on the dash) in parallel with my LED?

[Andrew F. Ali]

Re: Car flicker unit ...

Why not just build a two transistor flip-flop flasher instead???

[wee wee]

Re: Car flicker unit ...

What is a 2 transistor flip flop flasher ?

[wee wee]

Re: Car flicker unit ...

hoo ok will have a look.

This one look simple:

http://homemadecircuitsandschematics...istor-led.html

[wee wee]

Re: Car flicker unit ...

so how many ohms should that resistor be?

[stj]

Re: Car flicker unit ...

forget the resistor, it's a dumb idea that wil be huge and generate stupid heat.
it would need to simulate atleast 42w or lamps, maybe 50w including side-repeaters.

just use the 555 chip to drive a transistor connected to a relay.
or even skip the relay and use the 555 to drive a fet on a small heatsink.

[wee wee]

Re: Car flicker unit ...

do you maybe have sheme for me?

[wee wee]

Re: Car flicker unit ...

for the two transistor flip-flop flasher can i use a irfz44, yg225c2,d718 or k512 ????? I only have those ???

[stj]

Re: Car flicker unit ...

well i dont know.
you need a fet that can handle atleast 100w and have the lowest on-resistance you can find.
the lower the on-resistance, the less heat it will generate.

start by making a 555 circuit that flashes an led at the right speed, we can add the fet part afterwards.
it will be more easy to do this in 2 parts.

[budm]

Re: Car flicker unit ...

You should search for '555 application notes' to learn about 555.
I.E.
http://www.williamson-labs.com/555_apps.htm

It is best to learn how it works than just getting the schematic.

[stj]

Re: Car flicker unit ...

looking at the timing charts i'd say you want a 10uf 50v capacitor and a 220k variable resistor to set the speed across a good range.