Cellphone Triggered FireworksWith this tutorial you will be able to create cellphone triggered fireworks. Initially this was designed for a hobby rocket launch, but I found it was just as practical with fireworks . You call the cell phone, and it will auto ignite the firework/rocket for you with a fuse. I already built this a couple of months back, so you might see all the wires already soldered, as with this tutorial I went back and took apart the phone to take pictures for this tutorial. For the record, I did not come up with this idea, props go to a fellow by the name of John that attends my university for the idea and first build.
Note: I'm not responsible for what you do with this, or if you accidentally harm yourself. Only do this with fireworks/rockets if legal according to your state law.
Intellectual Copyright: I do not want to see this tutorial copied on any other website without my written permission.
- Disposable cell phone - $10 from Walmart (I used this model in this tutorial)
- Thyristor - $1.15 (I used the 2N6400G thyristor in this tutorial)
- Electrical Wire (STG) - $5/spindle
- Hobby Rocket Fuses - ~$5
- (Optional) AA Battery Holder Case - ~$4
- (Optional) Electrical Tape
The contraption is devised into 3 components. The Phone, the AA battery pack (or possibly a 9V battery taped to the back of the phone), and the the lead wires connected to alligator clips that will hook on to your fuse. I suggest using alligator clips as it makes it easy to take apart your contraption, and pop in a new fuse in place of the old one.
Lets first take a look at the phone.
The phone is a cheap $10 disposable phone that I got at Walmart. For our purpose, we will only need the phone to ring when called, so you don't have to buy any minutes for it. Basically when the phone rings, the phone sends out a pulse to the speakers. The phone has both a small speaker for the ear head, and one in the back for the speakerphone. The speakerphone receives a higher voltage, so we will be using that one for our leads. We're going to pop out the speakerphone speaker and take 2 wires and solder them to the leads where the speakerphone speaker was, and connect them to the trigger pin of a thyristor, which once it receives the trigger voltage, it will allow current to flow freely between the anode and the cathode. The kicker is that with the thyristor, current will still flow even once the speakerphone stops sending voltage, so I would highly recommend purchasing a AA battery pack holder that has an on/off switch to open and close the circuit. Once the thyristor allows current to flow from the anode and cathode, current will flow freely throughout the entire circuit, and most importantly, our lead wires connected to our rocket fuse (or LED for testing purposes).
Lets take a quick glance at the schematic here.
As a quick recap, current flows from the phone to the thyristor, which sends a steady flow of current throw our lead wires to the fuse/LED.
Go ahead and flip the phone over and slide off battery door, the SIM card and remove all 6 screws.
Getting the phone case apart is a bit tricky, as there are 2 latches on the sides, and one on the very top of the phone. I recommend lodging a screwdriver on both sides of the phone, and then popping open the case with a 3rd screwdriver wedged from the top.
Once you get the plastic case off, you will see the inside of the phone. The speakerphone speaker is inside the large rectangular-like metallic protective enclosure at the top, which just snaps right off. Once you pop the protective brick off, you will see the speakerphone. You can just pop off the speakerphone speaker as we won't be needing it, we'll be soldering our wires onto the leads where the speaker springs were previously connected to.
Go ahead and solder 2 wires onto the leads, one is positive and the other one is the negative lead. You can figure out which one is which by using either a voltmeter or a multimeter, and be sure to mark the ends of the wires with a plus (+) and minus (-), so you know which way to connect them with the thyristor/battery pack. Below is a photo of the speakerphone speaker that we pulled right out, which you can salvage for any future projects.
You can now snap the protective speakerphone brick back on, and string the wires through the hole in the middle. The more efficient way I found to have the wires come out the phone is to remove the headset jack from the side of the phone, and string the 2 wires through that hole.
I will not go through the process of describing how to solder the thyristor with the battery, as it's pretty self-explanatory from the schematic. I'd recommend trying it out on a breadboard before soldering the mini-circuit together. In the image below, I soldered the thyristor with the appropriate wires on a small PCB, that I covered in electrical tape, and taped to the top of the AA battery pack holder. There are 2 sets of wires with alligator clips coming from the battery pack/PCB, one to the phone, and the other to our rocket fuse (or LED).
Here is me testing out the phone with an LED to make sure it works correctly.
Once you know that your circuit works correctly, you can replace it with a rocket fuse. Once a certain current & voltage flows through the 2 ends of the fuse, the combustible power at the tip will ignite, which you will stick into the rocket or to a firework fuse. Even once the power ignites, the fuse will still work for a couple of more trials, as the thin metal at the end glows red.
Below is a video of me testing out the contraption by calling the disposable cellphone from my home phone.
A simple explanation of how the cellphone sends the signal pulse
- Replace the rocket fuse with a PIC/Arduino microprocessor and analyze the signal, and create a touch-tone signal analyzer, which you can implement into a cell-phone controlled RC car.
All the images should be back up now!