Reliable ON switch?

[MikeMl]

I am building a beacon transmitter for a high altitude balloon. The beacon needs to be turned-on with a small, light, rugged switch just prior to launch. The battery will likely be a Lithium **broken link removed**.

The switch must have a positive ON indication (visual check of the physical position of the switch handle) or other indication that consumes very little power. This is so it can be checked visually just prior to launch. Launch is in direct sunlight, so I want to avoid an LED indicator...

The switch must be mechanically guarded so it cannot be accidently turned off by being snagged or dragged (the ground, bushes, trees, parachute shrouds, etc) by being recessed and/or by using a positive locking switch with a Lift-over-center handle.

Current/Voltage is 6Vdv at ~100mA

Temperature goes to -50 deg C

I've thought about a NC magnetic reed switches (where the magnet holds the switch open and the magnet is removed just prior to flight)

It could be done by not installing the battery until just prior to flight.

It could be done with an insulating mylar tab that is pulled out from between the battery contact just prior to flight.

Anybody have any other ideas?

 

[Reloadron]

The mylar tab labeled in small print "Remove Before Flight" would likely be my choice. Simple, effective and no weight to speak of.

Ron

 

[JimB]

How about a small jack socket such as those used for connecting external loudspeakers to radios.
The type with a contact which opens to disconnect the internal speaker when the plug is inserted.

Such a scheme may enable a last minute battery check using an external meter.

JimB

 

[KeepItSimpleStupid]

I just don't like the idea of friction battery clips in flight. Is it just me?

You should see all of the contact arrangements available with a 1/4 phone plug. For instance isolated NO or NC contacts are available plus the normal set to check battery voltage. I just bought one a couple with NC isolated contacts.

 

[dougy83]

A slide switch with the stick/lever cut off is pretty robust and hard to accidentally operate. A touch of bright red/yellow nail polish on the sliding bit to show the ON position should make it obvious when it's activated.