Introduction: Scratch Built Launcher Controller for Pyro Model Rockets
WARNING!!! I've used a match (as a igniter) solely for the purpose of this test.
To launch your model rockets use always the electrical ones, made by www.EstesRockets.com
Anyway, I must admit pyro/model rockets are more exciting than water rockets.
In the last Instructable published, I've shown how to convert the water rocket launching pad
into a pyro one...
Browsing for launcher controllers, I've noticed they are big and, honestly, they are a bit expensive $19 to $33. In short words, I've decided to build my own one.
For this Instructable, you need:
1 12V Toggle Switch with Cover
1 12V Momentary Switch with LED
2 Alligator Clips
1 ABS Enclosure/Box
5 Meters (at least 15 foot) of Electrical Wire 18 AWG (22A)
2x 1.5V Battery cases
1x Fuse 10A
1x Fuse Holder (that is going to work as safety pin)
Soldering on iron
Step 1: Wiring Diagram
Basically you are going to create a "controlled" short circuit for the time you press the push button down. The igniter (please always use the electrical ones aka buy ones made by Estes Rockets), is made with a thin metal wire, with a very small section. The short circuit will literally burn the wire, igniting the solid fuel motor (please always use the original ones aka Estes motors).
Again, considering you are going to create a controlled short circuit, be sure 100% that every wire and connector is insulated, using heat shrinks tubes.
Step 2: Preparing the Launcher Controller
Drill 3 holes: the 1st 12mm (toggle switch), the 2nd 15mm for the momentary switch and the 3rd 10mm (for the fuse holder). I've drilled the 3 hole laterally because the front of the panel was already crowded.
Put both switches inside the box, but before remember to remove the nuts they are equipped with.
Tight the nuts quite strongly, to avoid any movement of the switches.
Step 3: Attaching the Battery Cases and the Alligator Clips
You can use 6 battery 1.5V AA to power your launcher.
Attach the back of the cases using some hot glue to the main box.
Using some soldering on iron connect the alligator clips (following the previous wiring diagram) to the other side of the 15 foot cable (Positive/Red - Negative/Black).
These type of connectors are perfect to grasp firmly the legs of the igniter.
Step 4: Testing the Launcher... Again... and Again!
As I previously mentioned, you are going to create a "controlled" short circuit, therefore check that the wiring and the insulation are properly done. Everything has to be assembled in a faultless way.
After all we just want to have some fun, being always safe.
To summarise, when the red cover of the toggle switch is down, the switch is in OFF position (LED off).
Once you lift the cover up, you'll be able to move the toggle to the ON position.
At this stage the LED of the momentary switch will turn on and you'll be ready to launch your rocket,
simply pressing the push button. I've add a fuse holder, so you can use a 10A fuse as a safety pin.
Test it and test it again!
Step 5: Have Fun and Most Important Thing... Be Safe!
Please follow the model rocket safety code, as model rockets may be very dangerous if handle inappropriately.