I built this ignitor to launch rockets for the school club which I co-founded.
Before I built this, we were plugging in a battery to a wire when we were counting down for the launch but with this system, launching is both safer(having 2 toggle switches that need to be flipped and LED indication on whether it is armed or not) and easier, no longer requiring us fiddling with a wire and a battery before a launch.
The frame of the controller is 3D printed with orange Ayce filament on a Wanhao i3 duplicator. The files for the print are available on Thingiverse.
The parts for this are mostly off of Aliexpress but the switches were lying around and to be honest I dont really know where they are from, however I found some that are very similar which I will link below.
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Step 1: Designing the Frame
I used fusion 360 to design this frame. Before starting, I used a caliper to measure all the parts I was using.
This step was relativly easy as all of it took place on my computor and it only took about an hour to complete start to finish including measuring the parts.
Linked above is a link to the thingiverse file with the STL for this frame.
Once I had designed the frame I printed both it and the lid.
Step 2: Assembly
1. To assemble, first clear all support material from the 3D printed frame.
2. Next, screw both of the toggle switches into the alloted holes and secure them with a hexnut.
3. Then solder the 220 ohm resistors to the cathods of the LEDs. Once this is done, stick the heads of the LED's into the holes at the top of the case.
4. Determine which legs of the switches are needed using a multimeter. When the switch is in a neutral position, they shouldnt be connected.
5. Make sure that you are connecting the correct ends of the XT60 connecters to the circuit, the angled side is the anode and the flat side is the cathode.
6. Follow the circuit diagram to assemble the electronics. The circuit is quite simple but the connectors on the switches are close so when soldering, be careful not to use to much solder to prevent causing a short circuit.
7. When all the components are soldered together, use hot glue on the components to prevent a shortcircuit in the future, then use superglue on the XT60 connecters to make sure they stay in place as batterys are being inserted and taken out.
8. Clean up the print of the lid and smooth out any rough edges, then using any screw that fits, close the lid of the igniter. Once this is done and all the glue has dried, it is ready to use.
Step 3: Using the Igniter
Plugging in a battery to the XT60 connecter on the back of the device will prime the igniter. This will be indicated by one of the LED's lighting up. In my case, I chose green. Next, if I flip the switch in the center of the device, a second LED will light up, indicating that the device is armed and ready to fire. If the third toggle switch is pulled, a current will flow directly from the battery to the XT60 connecter at the front of the device. If a fuse(or a wire connected to a fuse for safety) is connected, it will blow generating heat and igniting whatever needs to be ignited. I tested both an Estes rocket igniting fuse and a 10 ohm resister and when fired, both would ignite.