In this instructable I will Show you how I put together my controller that you can use as an alternative to the Estes box. This box dosen't really save you much over the Estes unit but it looks better and works better.
So why have a controller anyway? As stated by the NAR rocket safety code a controller with a safety interlock should be used. This isn't just to complicate things but it really is for safety. With a controller with a safety it is pretty much impossible to have accidental ignition like it would be with just a simple switch or just connecting it to a battery.
What you will need:
hot glue gun
pliers and wire cutters
xacto / razor
momentary switch, I have two but only one is needed
small bolts with two nuts to fit
battery or battery holder
molex connector or any connector that you have a male a female end to
here's a link to the NAR site for reference
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Step 1: Layout and Install
Once you have found an enclosure that will fit the battery / battery holder you will use you can plan the layout. A note about the batteries, avoid using 9v, sure you can add two of them and have 18v but they have rather crappy battery life and little power output.
Layout your components and mark where you need to cut. After cutting your holes make sure everything fits and mount them in place.
Don't forget to make the holes for your post on the front.
Step 2: Connect
Pretty much all the connections are in series with the exception of the leds if you use them. The schematic shows how things are hooked up. If you use the continuity led use a resistor a little higher then needed, the led should not let enough power flow through to set off the igniter but a higher resistor will help make sure. Two momentary switches are not needed but add a little more saftey. Your power source does not have to be 12v but you will want it to be more than 6v and be able to provide enough current.
All components of the launcher need to closed for the launcher to work.
Step 3: Finishing Up
Solder in the connecting wire on the molex to make the key.
Install your battery and test.
I have added a schematic with a rocker and leds, neither leds are really needed but nice to have and leds always make you project look better. More lights and swithces.
I used two momentary switches on mine for added safety as I have little ones launching with me. Attach a lanyard or something to the key and you can hang it around your neck.
The line going out to the rocket is around 25 to 30 feet, plenty of room.