Remote Start using Cell Phone: Part 2

With shutoff relay.

It works!  Not to spoil the punchline, but yeah, all the tests so far have worked out.

I received my breadboard from SparkFun and started assemblage.  I used one of the two optoisolators I found in an old board I scavenged from- something.  The optoisolator seems to be a good fit, at least for testing.  The input voltage (datasheet) for the IL203 is 1.2v – 1.5v, which nails my averaging output of 1.35v perfectly.  However, I do have some concern about the long-term operation of the optoisolator, as that voltage is rated at 20 mA and I measured the phone output peaking at just over 420 mA!  That kind of continued current may damage the optoisolator in the long term, but as far as I know that datasheet could be telling me how long to cook eggs, so you tell me?

Anyway, here is what I got hooked up and working:

Breadboard with IL203 hooked up.

All hooked up.

With that setup, I was able to kick off the vibrate on the phone by going to the menu and selecting the volume and get a nice tone out of my multimeter.  Further tests by calling my phone and setting the alarm revealed that all of the vibrate functions on the phone resulted in nice *fairly* steady, long pulses out of the vibrate circuit.  I took the setup outside and hooked the collector and emitter side of the transistor up to the part of the remote start that I wanted grounded.  Adjusting the volume twice (to make it ‘vibrate’ twice) resulted in the accessories kicking on and my car starting right up.  I was even able to repeat the process and shut my car back down!  (YES! *pumps fist*)

Here is a closer look at the whole setup so far:

Closer look at IL203.

Closer look at IL203.

Now the next part of the project was the part I was holding my breath on… Making the phone not shut down the remote start with consecutive pulses.  Again, a TON of thanks has to go to beegbie over at for his suggestion for this part of the circuit.  Brother, it works like a CHARM!

The idea was that certain parts of the remote start circuit are only active once the startup sequence is activated.  I chose to use the accessory circuit as it would remain on and keep the remote start from sensing any more inputs the entire time the car was running. (I am not worried, at this time, about being able to shut the car down since the remote start only runs for approx 15 minutes then shuts down on its own.)  I achieved this by splicing into the collector side of the circuit on the optoisolator (the vibrate output) and installing a relay.  This is your typical Bosch style automotive relay, and the idea was to have it triggered by the Accessory output on the remote start to open the circuit.  Besides the fact that I bought the wrong kind of relay (I bought a NO relay and I needed a NC relay, see how I modded it to be a NC in my other entry) and had to modify it, it worked PERFECTLY (YES! *pumps fist again*)

Here is a pic of the clustersuck setup I had for that:

With shutoff relay.

Circuit with shutoff relay.

With this all in place, a call to my car started it, and letting the phone continue to ring did not shut it off.  I killed the car at this point, and set an alarm on the phone for 5 minutes.  5 minutes later, VROOM!  Final test, I set an event on the calendar.  Later that morning, I was presented with the beautiful sounds of my broken exhaust springing to life!  I’d call that a success, wouldn’t you.

The next step in this whole shebang is to put the whole package into, well, a nicer package.  I have ordered a board, matching project box, jumper wires and automotive relays  from Parts-Express, and some low-current relays from Digi-Key.  These low current, solid-state relays should be able to handle the higher mA current better than the opto-isolators, and might even last longer.  I will say that the operating temperature of the optoisolators is better than that of the relays, which is of concern being jammed in a car in KY, where the weather can be anywhere from 0°F to 105°F.  This I don’t get (the operating temps, not the weather…well, I don’t get that either, but…) as the general operation of the opto and the solid state relay are basically the same, except the opto has a transistor on it’s output side?  (This I don’t really get either?)

So to conclude Part 2 of this mod, I am eagerly awaiting my orders from Digi-Key and Parts-Express (the coolest places have hyphens in their names).  Hopefully soon I will have Part 3 up and have a nice little packaged unit.  In the mean time, look for my post on how I modded a relay because I am too lazy to go drive around town hunting for the correct one.

Part 3

40 Responses to “Remote Start using Cell Phone: Part 2”

  1. [...] application where safety or reliability were a concern.  I used this particular relay for testing another project, but am going to purchase appropriate relays for the final [...]

  2. [...] out Part 2 to see if I can actually pull it [...]

  3. Ryan says:

    I think that’s awesome. I’ve always thought it would be cool to use a programmed thermostat to program times to turn the car on and off, but this WAY beats that idea. Great idea man.

  4. Gdogg says:

    VERY good. I like your implementation. Despite it being more hack-ish than the other method (on hack a day) it actually has more features. Using the stereo port is awesome.

    • admin says:

      Cool, thanks. I used the stereo port because I wanted to be able to disconnect the phone easily and program it and whatnot.

  5. silvio says:

    so how much does it cost altogether?

    how much for you to build me one???

    • admin says:

      Total cost is $71. To build you one. Uh, this system is not without bugs, and has a few security holes. I’m working on a better, easier solution already.

      • Ants says:

        Could you give me better part numbers of the relays you used? and where to buy, —until you get a kit together.
        Very exciting stuff! Great to see someone else thinks like me.

        • admin says:

          The relays (optoisolators) were actually from a scavenged circuit board from an industrial scale. The part numbers are listed in the writeup, I can’t remember them off hand.

  6. Brandon says:

    Hey man, what part of KY do you live in, im here in louisville and thats an awesome idea, would love to see how it looks mounted

  7. ttosbt says:

    Very nice! Let’s hope you don’t get any wrong callers at 2 in the morning, or ya might wake up to an empty tank.

    Maybe some sort of authentication could be built by decoding the tones from the output-speaker for an extra layer of security. That is if you could get the phone to auto-answer…

  8. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  9. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  10. TSwain says:

    Generally I do not post on blogs, but I would like to say that this post really forced me to do so, Excellent post!

  11. Aaron Anderson says:

    I’m also in Louisville…

    About security and the phone: I’ve never used one of those throw away style phones, but generally speaking phones have a way to have a different ring depending on who is calling. So you could kill the ringer for everyone (silent) except for your actual cellphone, where you could make it vibrate. Just a thought.

  12. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  13. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  14. [...] know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  15. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  16. Mr. O says:

    sorry bad grammar
    Maybe I am thinking to simply, but wouldn’t a ring tone (ding, ding) do the same thing??

    • admin says:

      I thought so too, but I think that the signal varies too much depending on the volume and duration of the (ding, ding), so I wanted something more consistent.

  17. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  18. tristan says:

    you could give your self a custom ring tone to fix any security issues.. only your phone would activate the phone thats modded.. would you know how to make a cheap thermostat run 1000 watt fan?

  19. [...] and know-how on your part, the end result is pretty cool. Remote Start using Cell Phone: Part 1; Part 2; Part 3 [Dave Hacks via [...]

  20. JC says:

    About the optoisolator current, that is not a max rating as in do not exceed it, that is a max rating as-in if you give it the voltage it needs, it might consume that much current.

    In other words, you could be using a 1.35V supply capable of 20 million amps (ok, it’s just an example nobody has a million amp 1.35V supply in reality) and it wouldn’t make a difference.

  21. Kai says:

    can u build one for, ill pay u. thanks

    • admin says:

      Sorry, this version is not THAT great. Slowly working on another version that should be “plug-n-play” for the average person.

      • Kai says:

        when u should be done with another version??

        • admin says:

          Sheeeit…My wife changed jobs and I watch my 4 year old and my 9 month old 4 days a week and I work nights. I barely have time or energy to keep the house/yard under control.

          The concept is still brewing, however. Thank for your interest.

  22. ikea says:

    have you looked into DTMF tones to trigger relays?
    this way, it wouldn’t matter who called, they would have to know the pin code in order to trip the relays. rainbowkits has a few dtmf circuits…

    nice work though. wish i had one!!

  23. matt says:

    what did you use for a remote starter?

  24. I went over this website and I conceive you have a lot of superb information, bookmarked (:.

  25. Cyberguy says:

    Thats an excellent idea! I work at a Airport in Ky (CVG) and here lately its a pain to wait in a freezing cold car. Thanks!!

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