Two Letters Re: Preparing for Survival Retreat Perimeter Defense

I noticed the comments about using 1960s vintage flash bulbs as tripwire warning devices for a perimeter. Something that I improvised and used successfully on active duty in the Army in the 70s was also based on flash bulbs. Remember the flash cubes from the 1970s? The four-sided flash bulbs that rotated and flashed on the mass market cameras of the era can be turned into effective and non-lethal warning devices. If they are still available, get a flash cube and look at the underside of it. You will notice a tiny ‘hammer’ that when released strikes a [“primer”-like]device which causes the bulb to flash. Place an opened paperclip between the hammer and “primer” to block the full travel of the hammer and then trip the hammer. The paperclip will stop it from going the full distance. Do this for at least one more of the flash ‘stations’ on the flash cube. Use clear mailing tape to bind the armed flash cube to a handy tree trunk, sturdy shrub, poll, or what have you. Run monofilament fishing line from the paper clips across the area that you wish to guard and anchor the far end. When intruders walk through the area at night and snag the line, the paperclip is pulled from the flash cube, it fires and simultaneously signals that an intruder is in the area and temporarily dazzles him! We used these during field exercises against the ‘enemy’ and the devices were highly successful. I imagine the flash cubes can still be purchased. Give it a try and see if it works! Best Regards, – Karl V., USA (ret.)

I wanted to clarify that you can just tape cannon fuse to a flashbulb – there is no need to drill a hole. If your particular bulbs have difficulty with lighting the fuse, then you can shave a little of the jacket from the fuse to expose the gunpowder core – then tape the fuse on, with the core contacting the bulb. This works great. – Matt