Tip: Walter s LED Lighting Project for Faller Hot Air Balloon Date:

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1 Introduction I take great pleasure in introducing Walter s first article to be posted in my Tips section of my web pages. All text and photos are by Walter unless specified. Ross Photo by Ross Walter s Balloon Project Many years ago I bought the hot air balloon kit made by Faller and it has been sitting in a cupboard unassembled. A while ago I had the idea that it would be neat to have it look like the gas burners are flared every now and then. Using LEDs was the obvious solution. Whilst googling possible colours I came across a type of LED I had not heard of before called flickering (as distinct from flashing). This is the type you find in imitation tea candles. Unfortunately the yellow colour is not quite as light as I had hoped and it lacks the blue base that a gas jet has and the flickering is a bit too slow but it is much better than anything else I could find. I also decided that the burners should come on periodically for shorts burst so this necessitated some timing circuitry. I also decided it should not have visible wiring so it meant a concealed battery and a switch. The only place for the battery and the circuit is inside the balloon. Serviceability had to be a key consideration so the circuitry in the balloon and the basket with the LEDs had to be removable. A simple idea now became a somewhat complex design. This is how I went about it. 1

2 Planning and Testing Fist I found a circuit in my IC Timer Cookbook and tested it on a breadboard: The circuitry is an astable which is on for 2 seconds and then off for 7 seven seconds. R = 1.25M Ohm - 1/2 W (for both phases) C = 2.2uF - 35V Tag Tantalum for the on phase C = 4.7uF 35V Tag Tantalum for the off phase 2

3 The next step was to figure out how to house the battery and the circuit inside the balloon so that it could be removed. The solution was to attach a male screw fitting to the circuit board so that could be screwed to another matching female fitting within the balloon. The challenge was that the interior was completely hollow, except for a narrow ring that supports the segments of the balloon, so there is nothing to hold anything in place. This made it quite tricky to mount the female screw socket needed to hold the circuit board and the battery. I decided that the best way was to glue the female socket to the hole cut in the bottom of a container that could be secured to a support from the ring. This picture shows the supporting MDF board that would hold the container glued to the support ring. 3

4 PCB Requirements The next step was to construct the circuit board with the battery. The left hand side shows the male screw thread. This is from a garden hose fitting: The right hand end has a different tap fitting with the connecting spout cut off. More about it later. The next picture shows the female screw socket when screwed on and the container to hold the female socket. A hole has also been cut in the bottom of the container. 4

5 The next photo show the hole in the bottom of the container where the female screw socket will be located and glued to the inside of the container: The hose fittings were perfect fit as they also provided a hole for the wiring to the switch and LEDs. This photo shows the complete assembly so far: 5

6 The next step was to mount he container in the exact position against the supporting frame: The reason for the grey tap fitting at the top now becomes clearer. It has the blue cap-piece of the balloon glued to it. This becomes the grip to unscrew the circuit board from the balloon when it needs removal. Unlike the conventional design the cap-piece will not be glued to the balloon. 6

7 The assembly was a bit unstable so a second supporting MDF board had to be inserted before the rear balloon panels were glued in place: Next, an open loop of thin wire was attached to the cap. This is the attachment point of the fishing line that will suspend the balloon. A this point the remaining balloon segments were glued into place thus fully enclosing the container that holds the circuit board, which in turn, has the hook for the suspending fishing line. 7

8 Assembly of the Balloon Cage Here you can see the assembly without the sides of the basket. The original burners will not be used. Creation of a bayonet-style key-way allows the basket assembly to be removed from balloon if required: 8

9 The next step was to install a tiny sliding switch to turn the circuit on and off. A slot was cut in the base of the basket and the switch toggle was trimmed back so that it did not stick out too far. The tabs with the mounting holes were also removed as the switch would be superglued in place. Once this was done the LEDs could be put in place: Note the use glad wrap to produce a more refracted appearance to the light. The glad-wrap is held in place by thin wire which is meant to look like the vaporising coils of the gas burners: 9

10 The four wires were then treaded through the hole of the hose fitting and soldered to a plug that connects to the header pins on the circuit board. 10

11 Once connected the circuit board was screwed into the container inside the balloon so that the blue cap was flush, and then the basket cage was clipped it place. Finally a nylon fishing line with a small loop was hooked to the balloon and suspended from a hook in the ceiling. Mr P. Enguine, a keen aviator, was seen at the controls on the maiden flight 11