Ready to control your synthesizer with a blowtorch?
This video documents a proof of concept test for the Thermatron, a vacuum tube synthesizer controlled by a flame, created and built by Lorin Edwin Parker at Electric Western.
The right mixture of gas, air pressure, high voltage, chemical ions and heat vary the flow of current through a flame. This current feeds into the grid and / or plate of vacuum tubes controlling an Electric Western Phantastron Synthesizer.
About The Thermatron:
The Thermatron is essentially a voltage controlled oscillator and wave shaper controlled by the action of a flame. This is possible because electricity can be conducted through a flame. This is not a new discovery, in fact the electrical properties of flame have been known for hundreds of years and well studied. For example, many hot water heaters have a sensor that detects flame by sensing the current inserted through the gas flame (if the gas flame goes out, the current does not reach the sensor and the heater knows that the flame is out).
It’s not as simple as lighting a fire and sticking it into the input of a synthesizer or a speaker, though. There are a number of things going on here and the impedance of the flame (how much electricity it conducts) depends upon air pressure, chemicals (gas and ionic environment), heat, applied voltage, surface area, etc. A propane flame alone is a poor conductor and does not react as well until more ions are introduced (you see that I add a chemical mixture which introduces ions to the flame like salt in water). The added ions allow the current to flow from point A to B much more easily.
Also, the hotter the flame and electrodes get, the better the conductor. This is because there is simply more energy in the system, more ions whizzing around faster, and more plasma. Within the flame there is some plasma (which is highly energized gas which gives off its electrons and conducts quite well), but only a small amount compared to the plasma generated in an argon gas tube, for example. The addition of voltage, or electrical potential through the electrodes also facilitates the creation of a more energetic flame-conductor and donates electrons to the mix.
So, as the flame heats everything up, including the added ions and metal electrodes, the whole space becomes more energetic and conductive. This space, like the space within a vacuum tube, can conduct electricity, so the 200+ volts applied to the top electrode are attracted toward the bottom electrode. Only a small number of electrons actually make it through this flame environment,though, because it has a high electrical impedance. The current which does conduct is on the order of micro-amperes, but the voltage potential is still strong…
See the Electric Western site for more details!