the tremolo unit fan box
Make the fan box from two pieces of MDF wood 6 mm, appr. 120x120 mm.
The sides are made from 4 mm plywood 20x120 mm.
The top side has a circular hole with a diameter of 100 mm.
The bottom side has a circular hole of 43 mm for the fan air stream.
The fan is mounted on the bottom with 4 20 mm M3 bolts and nuts.
Make two holes with a diameter of 10 mm on the rear side of the top part for the wiring.
Finally glue 4 little wooden feet under the box.
The cardboard disk has a diameter of 95 mm and can be provided with different patterns.
I used a purple color for the patterns because it had maximum effect on the light sensor.
Preparing the fan
he fan drives the disks. Glue a metal ring with a hole on top of the fan to flatten the surface. (It has a plastic bubble in the middle) and glue a flathead M3 bolt on top of the ring.
After adding the bolt immediately center the bolt by rotating the fan and pushing the bolt until it sits exactly in the center. Else you add a wobbely effect to the unit...
Adding the sensor holder
The sensor holder is made from 3 pieces 4 mm plywood , the sides are 50x55 mm and the top is 50x128 mm.
The front and back are covered with 1 mm white cardboard to keep the sensor in the dark.
Dimensions are 128x28 mm and 128x58 mm.
Make a small gap in the large part for the IR led wire.
Glue two pieces of 4 mm plywood 50x10 mm inside the top part to stop the holder from shifting to the left or to the right.
Glue all parts together and also mount the mounting plate underneath the box with two bolts and nuts M3 10 mm, sticking the plate far enough out on the rear side to mount the bits on it.
The light sensor and the IR led
Mount the light sensor and the IR led as shown on the picture.
I used 3 adhesive feet and the middle one was fixed on a small piece of plastic, bolted on the wood top with two bolts and nuts M3 10 mm.
The sensor is covered with a small piece of opaque plastic to make it less sensitive and the IR led, sticking through the wood is covered with a small black plastic ring to center the IR beam.
mount the bits on the mounting plate as shown on the picture.
The dimmer is used to control the fan speed and the output of the light sensor is used to send the tremolo signals to a noise maker where you have a zillion variations of noises......
The noise maker
This is one of many possible designs of a noise maker.
The Arduino is loaded with the Mini Pops program and can be heard via one synth speaker.
See for details of this drum program : http://littlebits.cc/projects/mini-pops-drumcomputer
The tempo trigger of the arduino controls a seqencer which triggers with every step a micro sequencer, set to 3 out of 4 sounds from an oscillator with a delay.
This sequencer also triggers the tremolo unit with step 2, vibrating the volume of a second oscillator via a filter (It is the br br br br br br sound).
The seqencer also triggers the MP3 player, conected to output number 4 and it makes a Theremin sound every time it is triggered. These sounds can be downloaded from
The delay bit and the tremolo filter are both connected to the mix bit and both sounds are sent to the second synth speaker.
The MP3 sound is connected to the mix bit also, but via two proto bits and a 1kOhm resistor connecting both SIG lines. This noise maker really needed a mix bit with three inputs....
Just for fun the RGB led bit and the bargraph bit are connected to step one and 4 of the sequencer.