The making of the Magic Xylophone

It was required to build a radio controlled children xylophone for the opera "The Magic Flute". As a member of the props team, it was decided that I would be the person to attempt such a task. The prop was to light up on command and the hammers which were to be placed on the prop were to move up and down to give the illusion of the instrument playing itself.

I had never built anything of such complexity before, however having worked with basic electronics before I had a small understanding of what was required. 

I am now going to explain how the magic was performed.

When I started the project I needed to understand exactly what it was going to do; how large it was going to be and what I was going to use to power it. With the xylophone being only 300mm in length, the space inside the prop was very limited, this however limited my choices of the following: A. Motor capacity, B. Power supply, C. Lighting capacity D. Radio Controller

After Talking to Martin Mallorie several times, and after much trial and error, I decided to build a box in the shape of the footprint of the xylophone. (wide at one end and gradually tapering in to the smallest bar) The first problem to solve was the motor to power the mechanism, After a trip to Maplins I purchased a 3v motor with built in gear box. I had to keep the motor small enough to hide inside the instrument but it had to be large enough to power the axle.

The lighting was the area of the prop i was most experienced with. Making models as a hobby, i regularly use LEDs as part of making the models. I decided to use 3v white LEDs , in the prop as these would give a bright coverage of light even at low voltages. I normally use a 9volt battery to power LEDs as these make the lights last for a long time. However due to the motor only running on 3v, i had to lower the voltage to the lights considerably, as 9v would have burnt out the motor very quickly.

Next to solve was the radio controller. This was the area of the prop that i had no idea how to even approach. As my knowledge of this was non existant. Another trip to Maplins, I purchased a small PCB radio control unit of both transmitter and receiver. After examining it, i discovered that it was incorrect and worked on a much higher frequency which would have interfered with the radio mikes used by the stage crew.