Custom Order: Fotosis No. 006, Bar Set, Optical Sequencer, Egg Beater Theremin / Part One...

Connie here. We've been working on a custom order set the last 4 weeks for someone I am very close to. If anything, I wouldn't think anyone else would be capable of supporting 'fotosis' like he has with this one project. In the infancy of our little 'business', it's the friends and loved ones who help us get through the days of uncertainty; the ones who understand our simple dream and allow us to feel that for everything we make, they truly want to be a part of our growing passion and humble expertise. (FYI - I thank all our friends at the end of our blog and also through regular posts)

This set will be showcased in a local popular bar downtown that is known for weekly live music. The requirements were in keeping with our love for recycled materials and parts, as the need for the instruments to be durable to withstand euphoric drunken customers and also the respect of a handmade retro aesthetic including Meccano pieces & salvaged vintage connectors.

We really enjoyed designing and creating this interactive ensemble, something that anyone passing by would want to touch (very important) and an experienced musician could properly plug and play with.


Here is John with the specs;

The optical sequencer contains two oscillators one generating a sine wave the other a square wave. These oscillators are set up as optical theremins, their frequency being determined by three LDR's mounted on the front or the unit.

There are also a number of patch leads, permanently connected at one end to the outputs of a micro-controller. These leads can be connected to banana jacks on the front panel allowing the micro-controller to send trigger pulses to opto-couplers that reroute the frequency determining components connected to the oscillators. The time between trigger pulses is set by a value read from another five LDR's that are connected to the analog inputs of the micro-controller.



Both sound producing sections of the unit are then fed into and mixed by a passive ring modulator before amplification. The resulting noise is a random series of beeps blips and noise that you can interact with by applying lights or shadows to the eight LDR's on the control panel.

The sound producing chips I used for this build were the XR2206 (Sine Wave) and a 40106 (Square Wave).

As this unit is for public use it was important to make the controls as simple as possible so the pots are all dual pots. Example the volume also controls intensity and the filter is also square wave frequency.

The matching theremin with the Egg Beater for an aerial is a solid state unit based on a modified schematic we found online a while back.

All of the materials used to manufacture the casings were found objects like Meccano, random collected screws, bits of metal and wood also a strange French industrial on/off switch.

The whole setup runs off a single boss PSA 230, 9v DC supply.

Part two of this post can be viewed here.