Even though I don’t even have a Swift yet, I want to find a way to make it talk. Now, before images of Knight Rider start popping into your head, let me explain.
In Slovakia the law states that when you’re driving, you headlights must be on all the time, day or night. Yes, this is often pointless when it’s brilliantly sunny, but regardless it’s the law. The problem is, I have forgotten to turn on my headlights sometimes when driving. I don’t do it often, but I have done it.
Another problem is that Slovakia’s police will stop you for not having your lights on. As I have witnessed, they won’t bother stopping you if you are driving fast and dangerously, but they will stop you if you are driving without headlights. Before you ask, no, I have no idea why.
Therefore if I jumped in the car and started driving without headlights for more than 15 seconds, I wanted to create a system that would say, “Zapnúť svetlomety” (turn on the headlights). Sounds easy, huh? Well, it kinda is, but it takes a little effort.
First, I need a circuit that activates a 15 second timer if the lights are off but the ignition is on. That means if there’s no power going to the lights, a timer will be started. That part is easy, because I can just use a normal €1.50 car relay like this:
So, the lights are off, but the ignition is on. By connecting a wire from the parking/dashboard lights to it, the simple relay above sees if the lights are on or off, and sends power in the direction of a timer circuit that I will make myself.
Now I need to point out that I know how a light bulb works, but I’m not very good at reading circuit diagrams and stuff like that. I blow up more things than fix them.
I had a look on the internet and found that I can make a simple 15 second, 12 volt timer for about €4 with a little patience and luck, using a popular microchip called a “555” chip. To learn more I went to an electronics parts shop and bought three last week to connect stuff to them and figure out how they work.
Fortunately there’s heaps of sites on the internet that teach you how to make simple circuits using this popular 555 chip. This site was very helpful for idiots like me, and I was able to build a flashing LED light in just a few minutes. I didn’t blow anything up either which was a surprise (and the reason I bought three 555 chips just in case!).
The circuit diagram above for example is from this site, where you just type in how long you want the timer to run, and it tells you what parts to use where. For 15 seconds I will need a capacitor rated at 47 uF to go where the letter C is, and a resistor rated at 290.14 Kohms to go where the Ra is. The + and the – is the power from the car’s 12 volt ignition circuit. I reckon I can manage that.
So, the relay is powering the above circuit, and after 15 seconds the above circuit will turn on and supply power to this thing below:
I bought a couple off this ebay seller for only €4 each including shipping. Cheap as, and yet so awesome. When it gets power from the 15 second timer, it will automatically play whatever MP3 is on the SD card (it has an SD card slot as you can see in the photo).
This little circuit above needs only 5 volts, but a car is 12 volts. That’s too much for this little circuit, so I bought a little step-down voltage changer from ebay as well. It looks like this:
So, to recap again, the relay will supply power to the 15 second timer; the 15 second timer will soon power up the sound player (running through the above voltage changer); and the sound player will play an audio recording of “Turn on the headlights” in Slovak.
Come to think of it, I could have it play anything I wanted. Maybe the sound of a dog barking, or the theme tune from the Simpsons – you name it!
Once powered up, the circuit will keep playing “Turn on the headlights” non-stop until you turn it off. And the way to turn it off is to just turn on the headlights. The relay will suddenly get power from the parking/dashboard light, and it will switch power away from the all the above circuits, and it will all go nice and silent.
The next little problem is how to get the sound nice and loud, because I want a decent volume. It doesn’t have to be really loud, but it should be noticeable over the road noise or the stereo.
Maybe I can use a couple of smaller speakers and hide them under the dash, but if the sound is too quiet, or too crappy, I’ll have to amplify it and try pumping it through the existing car speakers.
To do that I’d need a tiny little 12 volt amplifier, but I found out I can actually make one with a few little bits and pieces in a kit. They sell these kits at a lot of hobby electronics shops and off ebay. They look like these:
I can buy these little mono amplifiers at my local electronics shop in a kit for €4 which is nothing. Then I’ll have it connect to the driver’s door speaker and that’s it! I might have to use a diode (a little component that only lets current go in one direction) to protect this circuit above if I’m blasting the stereo. I don’t want the poor thing to go fizzle-pop if power from the stereo is feeding into it while it’s trying to tell me to put the lights on.
So that’s it. All this stuff that I’ve bought is probably still a few weeks away from arriving in my mailbox but it’ll give me a cool project. Now, what else could use a vocal warning in the car? Any ideas?
UPDATE: I’ve just had a brilliant idea. I realised I don’t even need the timer circuit. Instead, when the car turns out without headlights, I’ll just have the MP3 player turn on immediately, but I’ll put 15 seconds of silence at the beginning of the audio file. Genius!
I’m also getting a Raspberry Pi (mini computer board) which I’ll be installing into the car as well at some point in the future. More info on that later… 😉