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Author Topic: Automotive Flasher Relay  (Read 730 times)
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Hello all, I am new to arduino and this site and haven't done any programming in my life but want to have a go. I have a project in mind and would like to know what you guys thought on feasibility.

Basically I want to make a smart Flasher relay for my vehicle, I would like it to function as follows,

One touch of the column switch 3 indicator flashes,
Latched in position constant flashing ( as normal ),
Hazard warning lights switched one once, normal hazard flashers ( as normal ),
Hazard warning lights switched on off on within 2 seconds, indicator strobe effect ( recovery vehicle etc),
Finally load sensing so when a trailer is attached it flashes the trailer indicator reminder light on the dash ( optional but already does it on the standard relay)

I have already made a basic circuit with a transistor and a relay hooked up to the arduino and can control the flash rate of the relay by changing the time delay on the blink sketch, that is as far as I have got.

The problems with that are the relay is constantly ticking in the dash, and the switches just tell which indicators to light up and also I don't know how to implement a strobe effect with a relay.

Any help with programming or circuit diagrams would be much appreciated, please explain things in very basic terms because I am a complete novice, to explain the wiring of my Landrover better, here is a link to the wiring diagram for the indicators page 70

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/Electrical_Circuit_Diagrams.pdf

Many thanks in advance!
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I would think that in order to control all those functions you would need two relay outputs - one for each side. Then also three inputs (left indicator switch, right indicator switch, hazard switch).

Each input would need to be dropped from nominal 12V to 5V and it would be sensible to buffer it via a transistor to prevent any spikes getting through to your processor. I assume you already know how to drive the outputs via a transistor and flyback diode.

I'm not sure the 'strobe' modes are going to be very useful. Normally, strobe lights use a different type of lamp that is designed to produce a very brief but intense flash. The closest you could get with ordinary indicator lamps would be to flash them at a higher frequency than normal.
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I'm not going to attempt to write your sketch for you...

It looks like you just need some if statements and/or some if-else statments to control what your program is doing.    Conditional execution (if statements, etc.) and loops (doing stuff over-and-over) are the two most important concepts in programming.   They are the things taht make programming worthwhile.

I think you just need to read-through the Programming Language Reference and take a look at a few more examples, and then just start experimenting and learning!     Add a couple more lines of code to your sketch at a time to add features/functions.   

Do NOT try to write the whole program before trying it out!   Add a few lines of code at a time.   That way if there is an error or a bug, you'll know where to look instead of trying to find 100 errors at a time.  smiley-wink

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Hazard warning lights switched on off on within 2 seconds, indicator strobe effect (recovery vehicle etc)...
  That sounds like an if-statement that changes the delay time.

Quote
Finally load sensing so when a trailer is attached it flashes the trailer indicator reminder light on the dash ( optional but already does it on the standard relay).
I don't know how that's wired-up, but the Button Example reads the state of an input pin and with an if-statement, turns an LED on/off.  That should get you started.   ...Don't connect 12V directly to an Arduino input.  Use a voltage divider (2 resistors).
« Last Edit: February 06, 2013, 01:52:45 pm by DVDdoug » Logged

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I forgot to mention that I have a full led kit on my car, all the lights are high intensity LEDs, so the strobe function should work

http://www.mobilecentre.co.uk/index.php?main_page=product_info&cPath=36_37&products_id=440 << lights I have fitted

Please could you explain driving an output with a transistor and fly back diode?

Cheers, George

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The Arduino outputs supply 5V at up to about 20mA which is not enough to operate a typical relay, and they will not cope with the EMF pulse that occurs when the relay is switched off. So, you need a little external circuit between the Arduino and the relay. In its simplest form it would consist of a transistor, resistor and diode. There's a whole section of the forum dedicated to issues relating to driving high powered devices from an Arduino and you will find plenty of explanations there.
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