Tired of depressing that silly little button-switch on your laser pointer by using an “O” ring or a piece of dripper hose etc when you want to keep it switched on? These great little ergonomic sighting aids can be a bit of a problem with that hold-down switch when mounted: you’ve got to be able to switch them on and off because they drain their AAA batteries fairly fast; and other folks don’t like you having them on constantly either (eg airline pilots, astro-imagers etc.) – not to mention the possibility of upsetting their alignment in the mount when fiddling to switch it on and off!

My solution was cheap and simple, and like most things I do I immediately saw refinements to the mark 1 version. It consists of a “banana plug socket,” a “banana plug” and a miniature stdp (single throw double pole) switch from Dick Smith’s to solve the problem: total cost $4.75. (Dick Smith P1720 & P1740 & P7673)

These laser pointers have a metal screw-on end cap for battery replacement; and this cap serves to “earth” the positive end of the batteries to the metal body of the “pen” –the circuit is completed internally to the negative via the button switch. By drilling an 8mm hole in this end cap and filing just a tiny smidgin off the outside rim of the plastic insulating sleeve, the threaded section and its insulating sleeve can be inserted into the end cap (from the inside) through this 8mm hole; one then only has to place the spacer sleeve back on the threaded section that protrudes out through the cap and screw up the washer and holding nut to isolate the battery positive from the pointer’s body.

Image 1 shows a dismantled banana plug socket’s components from left to right: nut (not used)  tab terminal (used on pen clip) nut, washer, spacer sleeve, plastic insulating sleeve and threaded section, and above all of these is the drilled laser cap with re-assembled bps. Image 2 shows the finished article.

Click to Enlarge The components of the banana plug socket		Click to Enlarge The finished green laser pointer

This means that now, if the button switch is permanently depressed, you can use one of the wires in some speaker flex etc connected to the banana plug which is plugged into the banana socket (albeit from the rear) and its other end to a switch, and then back from the other side of the switch via the second wire to the pointer body to switch the laser on or off at will: easy operation and no disturbing of the pointer in its’ mount!

I used the washer tab terminal at the end of the second wire so it merely “clips” under the laser pointers “pen clip” feature to provide the return circuit to the pointer body.

The ring/band I use to permanently depress the laser’s button switch in the on position is fashioned from what is called a  “jump ring” in the jewellery trade: other devices such as very close fitting tubing etc slipped/slid (obviously with a bit of force) over the pointer to hold down the button are just as viable. Jump rings can be made by tightly winding a number of turns of reasonable gauge galvanized wire around some dowel etc having a diameter slightly smaller than the lasers: if you then slice longitudinally through the created “tube” of wound wire with a thin blade (hacksaw, angle grinder etc) you end up with a number of circular rings, one of which can be used to slide over the laser to permanently depress the button switch.

Variations of this set-up can be adopted to make more (or less) aesthetically pleasing arrangements.

Article by Darryl Pfitzner Milika (Kokatha man). Discuss this article on the IceInSpace Forum.