Like any any item attached to a helmet, the unit described below may compromise it's performance to some extent. Anyone choosing to fit a unit such as that described below has to take the responsibility of deciding for themselves whether it is safe enough.

Decent headsets for paragliding seem very hard to come by and it is difficult to make one both practical and robust enough for our use. This unit was originally made to fit inside a Kiwi helmet which had large internal spaces but has since been adapted to fit some other types. Without ordering and carriage charges the components should come to less than about £15 and it is fairly tough and easily repairable. Mail ordering components for a single unit would probably put up the cost by a further £5. It would have been nice to have been able to disconnect the lead from the helmet when not in use but I have not yet found a way of securing cables to connectors which resists pulling out well enough. Note that a large area of the board is devoted to anchoring the cables. A key component is the curly lead and earphone which I obtained from a speaker/mike costing £9.95. The microphone from this unit could certainly be made to work with this headset but the specified unit was chosen to be compact and robust.

Although not particularly complicated, the unit is quite fiddly to make and the following description assumes the constructor has some experience building electronic devices.

The larger of the two jack plugs connects to the earphone via the red and black wires of the curly lead. The speaker used as an earpiece is rather sensitive and this can make adjusting the volume rather difficult. A 47R resistor reduces the sensitivity and 'spreads' the volume settings. If the volume obtainable is too low it can be reduced to about 10R or replaced with a wire link.

The original unit was built on epoxy glass stripboard but SRBP stripboard should be OK even though it is not quite as strong. The speaker/mic. is easily dismantled to obtain the curly lead and loudspeaker which is then used as an earphone. The cables are anchored by tie wraps inserted from the top side of the board into four slots made by joining up pairs of holes. The earphone is fitted so that the diaphragm faces the veroboard for protection and secured by two wire straps and the two connecting wires made of 0.5mm (24swg) copper wire. Although facing away from the ear it seems to work well. An alternate earphone is listed later which may be more robust.

The PTT switch is mounted on the copper side of the board in a position which places it in the ventilation hole in the side of the helmet. In this well protected position it can be activated by the pilot 'putting his finger in his ear' so no external wiring is required.

Burnt flux can sometimes become conductive, so after assembly be sure to run a screwdriver blade or similar between the tracks to remove any flux or whiskers of solder which might be bridging the tracks. If you expect the unit to be exposed to much damp then clean the board with methylated spirit or similar and apply a coat of protective laquer.

The best way I have found to secure the microphone insert to the cable is to use a short length of adhesive heat shrink sleeving about 3.5mm bore (before shrink) to 'fatten' the cable behind the microphone. A second piece about 6.5mm bore is then used to cover the insert and secure it to the smaller sleeve. Alternatively the insert may be covered with heat shrink sleeving and gaps filled with silicone sealant. The microphone cable needs to be about 240mm long.

The earphone is pressed into the foam and the positions of the components and the cables marked where depressions are left. Recesses can then be cut in the foam to accept these so that the board can be made to sit against it. The board is secured to the foam with two tie wraps passing through holes in the foam (not illustrated) and passing across the copper side of board. The metal plate securing the helmet strap to the helmet is covered with two layers of Duck tape so that it will not short circuit the board. The helmet lining is then partially eased from the inside of the shell to allow the curly cable to pass through. The board unit and foam are then pushed into the ear space and the microphone trapped between the lining and the shell somewhere near the mouth.

The Lazer 'Downhill' helmet to which I was asked to fit a unit differed from the Kiwi in a number of ways which required a different approach. Most importantly the helmet had a circular mesh covered ‘hearing hole’ much larger than the Kiwi and the attachments for the chin straps were above the ears. Firstly the circuit board was made larger and two areas of self adhesive 'hook and loop' ‘hook’ material attached.

This helmet has a curved ear slot at the back of a raised circular area over the ear. The slot is just large enough for the PTT switch to sit in. To make the PTT switch go as far back into the slot as possible the board was made like the Lazer version above but two extra holes longer on the right hand side and shaped as in the drawing below. The switch was fitted two holes farther to the right and an extra wire link fitted to connect it to the original track. On the first one made for this type of helmet the 47R resistor was replaced with 10R to increase the earphone volume.

'Hook and loop' 'hook' strip is fitted to the board as with the Lazer version and 'loop' strip fitted to the foam which covers the strap anchor in the helmet. There seems to be plenty of space behind the internal lining of the helmet. In this helmet the foam inside the chin guard is quite dense and the microphone will not work when fitted between the lining and the shell. It has to be exposed, either by making a hole through the lining and passing the microphone through it. Alternatively the microphone cable may be passed over the top of the lining and the microphone fixed inside.