Electrical Switch Lock

           I am electrical intolerant; I know that if I push a light switch up, the room illuminates, and vice versa. I like simplicity when it comes to avionics, and these Electrical Switch Locks have that required characteristic. I only need the switch to reliably arm my avionics when I need it to, and power down to safe the altimeters and pyros without issue. I have used switch locks for years, and I try to tell anyone who asks, that Electric Switch Locks are an excellent and reliable way to arm rocket electronics with just a turn of the key.  As seen in the photo, the switch lock is a simple barrel type lock. Keying can come in many forms, what is pictured is a single bitted barrel key, which fits a lock mechanism that rotates ¼ turn for actuation. This type of switch lock, and all of the ones that I currently use came standard issue on many computers prior to year 2000.  I managed to scarf mine from old dilapidated Gateway 2000 computers that were being scrapped at work.

            Typically, Electrical Switch Locks are rated 10 amps @ 240V and were single pole – single throw.  Now a simple search will net many different variations of this design, but this is typical of the locks that I currently use on all of my rockets.

            Most switch locks are panel mount, and are held in place with a retaining nut.  Obviously, the switch lock is designed for a flush mount, so a little RTV sealant can be used to seal the lock to the rocket airframe. The wire and lug assemblies are removable for repairs or modifications, for as I found out, the internals of the switch locks cannot tolerate the high temperatures of the soldering process, and will become easily damaged.

            I mount these locks directly to the mid-point of the electronics coupler of the rocket, and the two halves of the airframe are relieved to make for a nice clean fit. For simple projects up to and including 4″ diameter airframes, I use a single switch, or rather one switch per altimeter. 

Pros & Cons 

Pros: 

• Cheap
• Reliable
• Simple to use
• Mounts cleanly in airframe
• Comes in many variations to suit most amateur rocketry avionic needs
• Requires key to arm, no throw levers or knobs to bump 

Cons: 

• Sensitive to soldering processes
• Replacement wire lugs can be tough to come by without having to purchase a new switch lock
• Must have key to arm, don’t loose the key 

            Is this the only method for arming avionics? Most certainly not, just one of many possible variations as I am sure that there are better and cheaper ideas out there. One thing for sure, it is much safer than twisting paired wires together. Other than rummaging old computer shells for their switch locks, I have not found a local source for the device. However, the internet is full of websites that sell them. There are far to many venders, and variations of locks to list them here, so I bid you happy hunting!

See you on the field, 

Johnnie