Step 1: Disassemble + drilling holes
The most important things we need are inside the Original Flash lights. This means we need to disassemble the whole thing.
First we disassemble the lights head, because we will need all the inside components later. We need 1 pen with both sides sending IR light, so we need the light head two times. This means we have to take of the second lights head too and do the steps below.
Second of all we take out the fixing ring. This ring provides a fixation but also conduction (this will be explained later).
After taking out all the parts, we can start with disconnecting the leads from the little PCB with a soldering iron.
Last off all we need to disassemble the back switch. This is a bistable switch that we will need later. (On the picture on the left side, next to the monostable switch on the right side). We only need to do this on one light (we need just one bistable switch).
We need to drill 2 small holes in the tube for the position of the 2 switches. Try to drill with a fixed drilling machine; this makes the hole straight and in the correct position. After drilling, use a Dremel saw to work the edges.
We also need just one tube, so there no need to drill the holes in the second light tube.
Step 2: Solder
The next step is basically just soldering the leads and the ground contact.
With 4 leads we need one color led and one IR led on each side. The position of the IR led is important, the color led may be placed the way you want.
The function of the color leads are to indicate if the IR leads are working.
The IR led (black) must be placed in the middle of the PCB. Otherwise it will not send its infrared light in full capacity. Make sure the leads are connected with the plus and minus in the right way.
After this we need to connect the PCB with the housing (thread). We do this by using two small conducting wires.
We bend a little corner to solder them to one of the four spots on the side of the PCB. Make sure that they make contact with the housing case of the light head.
At last we drill a little hole in the middle of the plastic assurance. This provides a little space for the IR led on that position.
Now that everything is fixed we can return the PCB, along with the other parts, back in the light head.
Step 3: Battery holder & switches
Here comes the hardest part.
We are rebuilding the battery holder to a super compact (with switches) non-slid component.
First we need to take out all the batteries and take one battery holder away (later to fix the switches). We take this holder away by taking away the plastic material with a filing device. Take away just enough material until the bistable switch fits in perfectly (picture 2). The monostable switch can be attached on top of the bistable switch. Make sure that the switches match with the positions of the drilled holes in the tube.
Author: Beackmaniax on Instructables.com