Running many LED's of alarm

Hi, continuing VW Golf custom alarm.....

we are running 6 blue LED's off the 'passive' immobilsor we added. Due to the unit not capable of running more than 2 LED's, we have added a small 'chip' style relay. The units LED output feeds the two coil pins and the LEDs are feed off the contact outputs. We use a chip relay because it is very low current (no battery draining problems) and almost completely silent.

Problem is the chip relay fails after 8 days or so. It doesn't seem to like opening / closing continually for this length of time. Understandable- these chip relays aren't really designed for this application.

What I want: a transister based circuit that will handle continual 'switching' and the current draw of 6 + bright LEDs. And be reliable.

We need to run 'normal' LEDs (as opposed to standard 12volt flashing) due to the LEDs showing diagonistics- variable flashing rates depending on status of immobilsor.

The immobilsor LED output is : 12volt continuous on one wire with a switching 9 volt on other: i.e. 2~3 volt difference.

The 'extra' blue LEDs are currently wired with resistors individually in-line- to run off 12volts. Obviously this can be changed if need be.

Thanks in advance,

Glynn

you dont have to do that. since you have a good alarm this is simple take one relay and what you are going to do is tap off the negative when armed output of alarm it is usually orange and used for starter kill .  tap off of that and connect it to pin 85 of a normal 5 pin 40 amp relay

after that take pin 87 and pin 86 connect the two together and run a fused 10 amp constant wire to them .

after that pin 30 is your output to the leds this is a possitive output so all you have to do is ground the leds and you only need to run the possitive to the leds . you have to make sure the leds are 12 volts  if not here is the run down of resistors you will have to use on each positive line to each l.e.d .  

6 volt leds   you need a 100 ohm resistor with 5 % tollerance,

with anything under 6 volts you need a 230 ohm resistor .

i custom did my alarm and i have 13 leds flaching blue ones . in dash, on doors, one screws for licience plates. etc.

both kinds of resistors should be 1/2 watt/ 5 % tollereance.

Sorry Jon, that is not what I am after.

That won't give me variable flashing. 85 to ground when armed and 86 to 12volts gives me constantly on LED's. I don't want that.

I want the LED's to be able to flash fast while the immobliser is 'arming', then at their regular rate when its armed. Plus able to give the diagonistic codes when its disarmed (if activated in our absence).

Plus, our standard LED's are 2volt-needing around a 560ohm resistor for a 12volt feed.

I definatly require the circuit I originally wrote about.

It basicly needs to act as a DC current / voltage amplifier.

anyone else???

Cheers,

Glynn

hello,

glen & jon,

can i use the starter kill wire to run 2 varad leds and the relay for the ignition kill?

thankss

Anyone , any ideas ?

Cheers,

Glynn

Thanks Karl,

The output from the alarm on the two led wires is : one at 12volt + , other at a switching 9volt+.

I do require a tranistor circuit, but won't it require limiting resistors etc as part of the circuit ? Surely its not just a case of alarm on one transistor leg, 12volt on other and LED on third ? If so, easy.

The LED's are standard 2.6volt, 20mA . 

Hope this helps,

Cheers,

Glynn

ok, i had to redraw it, so its on my previous post, no sense and having it picture twice. Well given that you have 6 leds, you would get about 120ma current draw if you wired them in parallel on a 12v supply from the transistor. Use ohms law to figure out the resistor value.

I know you can use one transistor but i believe you will get a max of 5v out of the transistor and not 12v. I can't remember, but i know the diagram above will work.