This robot was named after Luigi Russolo, the most wellknown musician-member of the futurist movement at the start of the 20th century. Just like in his pretty primitive designs, we make extensive use of acoustical amplifiers in this design. So, in a way, building further on principles highly developed during the period mechanical roll players and grammophones were developed. The sound sources used here are mainly springs, steel ribbons, membranes and rubbed strings.
It consist of a variety of very different non-pitched noise sources. Here is an overview:
1.-Excited spring with acoustic amplifier: This component uses a very long spring held between the anchor of an electromagnet at one side, and the membrane of an acoustic compressor at the other side. The acoustic compressor is coupled to a conical horn, in fact taken from an old bugle. The resonant frequency of the horn corresponds to midi note 56.
2. A second second sound source with similar excitation and membrane. For this one we modified a compressed air horn.
3. The third sound source is again a spring, but this time coupled to a brass membrane on a modified ships horn. The electromagnet used here is taken from a door closing mechanism.
4. A fourth horn, a linear cone in brass taken from an antique hooter, uses a smaller membrane again made of polyacetate.
5. A modified signal horn with a steel membrane, coupled to a very fine spring rubbed with a small DC motor.
Midi implementation and mapping:
|subject to changes during the building process||
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12.06.2014: Construction of the first electromagnet assembly. Testing of force and functionality.
13.06.2014: Construction of the acoustic amplifier with a horn. The membrane was made from polyacetate
14.06.2014: Welding of a holding construction for the horn and the driver electromagnet.
15.06.2014: Selection of suitable horns for the construction of more acoutstic amplifiers.
16.06.2014: Construction of the membrane for a second acoustic amplifier. Design of the mounting.
17.06.2014: Discovered another identical electromagnet in our junkyard. Mounting flange for the second horn welded. Horn re-assembled with the acoustic amplifier.
20.06.2014: Works on the construction of a thirth membrane amplifier, now using a thin brass membrane.
21.06.2014: Sketching of possibilities for an overall shape of the rumo robot.
22.06.2014: Another conical brass part found at the flea market. Useable for a linear horn and a small membrane. Silver soldering works on the combined structure. Orifice size for this one is 8 mm. The membrane could be polyacetate, steel or hard brass.
23.06.2014: Experiments with door closing electromagnets, as these have very high holding force. DC-Motor experiments for rubbing strings conducted as well.
24.06.2014: Mounting of the third horn assembly on the main structure. Electric tests: the electromagnet is designed for 12V (5W) at 100% duty cycle.
26.06.2014:Some new DC motors ordered from Farnell. Required for the spring
rubbing mechanism. Work for <Rumo> slowed down a bit, as we needed to
be working on <Zi>.
30.06.2014: Start of adding testcode in GMT. Further work on <Rumo> postponed,
as we have to get on with <Zi> first... It looks
like we cannot advance until at least november 2014...
13.09.2015: Time-space in sight to go on with the works on <Rumo>...
Electromagnets used for the two springs with acoustical membrane amplifiers: Grundig Radio Werke Gmbh, Relaismagnet 38/33. DC resistance: 55 Ohm. These components were taken from relays. They have a laminated core and thus can be operated with AC..
by Godfried-Willem Raes
Further reading on this topic (some in dutch):