A-Z of car ignition systems

  • ok so in this thread I would like to put together an A-Z of building your own car ignition system
    im writing this for all the people like me who really struggle with looking at wiring diagrams and such.....

    follow on from previous topic HERE

  • ok so work in process ......
    currently working off @lokki design he gave me at the following link here!
    following is the shopping list so far

    breadboard type stuff to put board on
    1 x arduino Nano
    1 x elechouse PN532 v3 Reader (cant substitute from all ive read...not worth the trouble)
    2 x 1N4001 diodes
    2 x resistor (50k)
    2 x resistor (100k)
    2 x NPN transistors (size doesn't matter?)
    2 x 10 uF Electrolytic capacitors
    2 x relays
    ◦Panasonic DS2E-SL2-DC5V latching relay
    ◦LZ-12H-K momentary relay

    computer IDE power leads will be sufficient for connecting external devices such as cabled to colum and cables to reader. probably main power in as well...clean and secure connection

  • so thanks to the listed page

    I found the following information
    Here are some rules of thumb when guessing at a good pullup/down resistor value:
    •For most things, 3.3k to 10k ohms works just fine.
    •For power sensitive circuits, use a higher value. 50k or even 100k ohms can work for many applications (but not all).
    •For speed sensitive circuits, use a lower value. 1k ohms is quite common, while values as low as 200 ohms are not unheard of.
    •Sometimes, like with I2C, the "standard" specifies a specific value to use. Other times the chips application notes might recommend a value.

  • based on the above information ive changed the shopping list two show two 50k Ohm and 2 100k Ohm resistors
    ill start with the 100's and if that is too much resistance I will switch to the 50's

  • Community Helper

    @MarkGabb said:

    im writing this for all the people like me who really struggle with looking at wiring diagrams and such.....

    Sorry... I find schematics far easier to use. ;-)

  • @Lokki lucky you....
    Is the some way to turn on a insert photo feature? I see it used to be done or is it restricted to certain users?

  • Community Helper

    There is, the same way you were doing links earlier just with an exclamation mark leading. I think it's down to the google drive link being unfriendly - I use imgur instead.

  • Board design to make everything fit..
    not having bought parts yet im unsure as to how big this puppy is

    Prototype board

  • from www.digikey.com.au

    2 X 497-2595-5-ND TRANS NPN 30V 800MA TO-39 AU$3.94
    2 x P10316-ND CAP ALUM 10UF 50V 20% RADIAL AU$0.78
    1 x Z2775-ND RELAY GEN PURPOSE SPST 5A 12V AU$1.50
    1 x 255-1066-ND RELAY GENERAL PURPOSE DPDT 2A 5V AU$7.57
    2 x PPC47.5KYCT-ND RES 47.5K OHM 0.4W 1% AXIAL AU$0.62
    2 x PPC82.5KYCT-ND RES 82.5K OHM 0.4W 1% AXIAL AU$0.62

    From elechouse.com
    1 x PN532 NFC RFID module V3 kit Approx au$30.00

    from core.electronics.com.au
    Nano 3.0 Atmel Atmega328P Mini-USB Board w/ USB Cable for Arduino AU $8.99

    anyone able to throw in opinions or perhaps ways to drop the price down a bit? i notice the main price is simply from the arduino, and not knowing anything about them am unsure if this is normal pricing or a rip
    yes i am aware im mostly using australian sites, but i have tried to include manfacturers codes to make it easier for international search

  • @lokki you are correct i do have an OBD port just didnt realize it was there untill now

  • Community Helper

    Personally I'd grab a clone nano off ebay or dx.com or similar. Don't get a clone of the reader though.
    Something like this perhaps.
    I've edited one of your posts to show the picture, you can have a look in edit yourself to see how to embed images. I used a different link address from imgur that's specifically for that purpose.

  • @lokki good call, ive altered my shopping list appropriatly....at the cost a genuine it just didnt seems like it would be a viable option if i need a genuine for every product.....

    ok so if all parts look good ill be ordering tonight....
    after much debate im going to give a standard ring a go and see what happens

    @lokki your a treasure chest of wisdom in here. would have already given up on understanding otherwise...
    Keep up the great work

  • Community Helper

    Genuine is nice if you can afford it, but clones are excusable as long as they're not using the arduino name to promote themselves. Arduino is open source but the name is a different thing.
    You're doing well here, it's good.

  • would be nice if a single site sold everything

  • @Lokki im a bit worried about this part

    i dont know why but it just doesnt seem right

  • Community Helper

    That link isn't showing up for me, are you able to give me a part number?

  • @lokki 255-1066-ND on digikey.com.au

  • Community Helper

    @MarkGabb said:


    ok, my bad. The diagram I knocked together for you was related to a motorbike project I was asked about... so while it's relevant it's not as relevant as it could have been in a better world.
    The Panasonic relay is a latching type, what it does differently is that when you trigger one side of the relay coil it locks in position one way, then you trigger the other side of the coil and it releases. This is what you'll use to set the car OFF or ON. We use this one so that if power is lost to the arduino for whatever reason then we don't suddenly lose power to the car while driving.

    Again, my fault entirely. This makes the following change - you have three outputs from the arduino instead of only two. All three are basically the same, transistor/resistor/diode, and two of them go to the same relay.
    I haven't got a picture of the latching relay for a fritzing diagram unfortunately.

  • @lokki all cool good sir. So if I just add another transistor and resistor with a diode in between. But put it to the second part of the relay? So does that mean I did select the correct part?