W9YA Elegant Launch Controller
The Rocketeer's favorite Launch Controller System
One of the more interesting aspects of this design is that it can be changed easily once understood. One thing I could not find easily at the local stores was a small keyswitch that would fit the Remote Unit's project box size I chose. I could have elected to do without this popular style interlock switch and just use a missile-launch-style switch with a disarming guard cover. If I felt the need to assure the switch isn't operated from the Remote/LCO position when I am at the Pad end of things I can always easily unplug the Remote Panel/Box and carry it out to the pad much like the key from the keyswitch can be hand carried out to the pad area to assure no unexpected launches when working near the rockets. Tom Beach suggested that I use a phone plug as the safety switch, and so I modified one by shorting a 1/4 inch two-conductor one internally and that works quite well.
I elected to use a 12.5 amp/hour gel-cell battery to power the unit so I used 14 gauge wiring and a 15 amp fuse and appropriate holder. If you decide to use a bigger battery to ignite your large clusters, be sure to upgrade the fuse, the wire gauge for the current, and your alligator clips for battery connection. If you need a tremendous amount of current (more than 40 amps,) you will also need a higher current relay and perhaps higher rated toggle and pushbutton switches. Above 60 amps you will need to examine every part in this unit. What you will need to upgrade will depend on how far above 60 amps you want to go.
You can choose to change the size of the boxes, use metal toggle switches for extra long life, and so forth. I recommend not removing the access cover from the arming switch as this can be used as an immediately accessed safety by simply closing the cover. Whatever you decide to do that modifies the parts used or the design itself is your decision, but if you change the design or the parts used YOU assume liability for any resulting loss is safety. Please be careful not to downgrade the ratings on any parts. The high-current safety switch used on the pad/relay box should NOT be replaced as this is a robust and very high current switch and you might run into safety problems by switching this for something smaller. (Fortunately this launcher's design and test procedure will alert you during pre-flight testing if there are welded switch contacts as a result of using an underrated switch !)
I was told that Radio Shack no longer offers the three buzzer parts from their website. However Radio Shack merely changed the numbers associated with these parts. Nonetheless substitutions can be made HOWEVER be sure to get units that do NOT use more than 4 ma current in operation and that will reliably operate over a range of at least 4 to 24 volts. Successful alerts and the low current operational features of this unit are dependent on proper substitution of these critical parts.
Rocket Graphics courtesy of the Crystal Space Community.