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Teledeltos
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Teledeltos
Teledeltos paper is an electrically conductive paper. It is formed by a coating of carbon on one side of a sheet of paper, giving one black and one white side. Western Union developed Teledeltos paper in the late 1940s (several decades after it was already in use for mathematical modelling) for use in spark printer based fax machines and chart recorders.
Teledeltos paper has several uses within engineering that are far removed from its original use in spark printers. Many of these use the paper to model the distribution of electric potential and other scalar fields.
Teledeltos provides a sheet of uniform isotropic resistivity. As it is inexpensive and easily cut to shape, it may be used to make resistors of any shape needed. The paper backing is an insulator. These shapes are usually made to represent or model real-world examples of a two-dimensional scalar fields, such as an electric field, or other fields following the linear distribution rules.
The resistivity of Teledeltos is around 6 kilohms / square. This is low enough that it may be used with safe low voltages, yet high enough that the currents remain low, avoiding problems with contact resistance.
Connections are made to the paper by applying areas of silver-loaded conductive paint and attaching wires to these areas, often with spring clips. Each painted area has a sufficiently low resistivity (relative to the carbon) and to be assumed to be a constant voltage. With the voltages applied, the current flow through the sheet will emulate the field distribution. Voltages may be measured within the sheet by applying a voltmeter probe (relative to a known electrodes) or current flows may be measured. As the sheet's resistivity is constant, the simplest way to measure a current flow is to use a small two-probe voltmeter to measure the voltage difference between the probes. As their spacing is known, and the resistivity, the resistance between them and (by Ohm's law) the current density may be determined.
A sheet that is large in comparison to the experimental area is usually sufficient for modeling an infinite field.
Although the modelling of electric fields is itself directly useful in some fields such as thermionic valve design, the main practical use of the broader technique is for modelling fields of other quantities. This technique may be applied to any field that follows the same linear rules as Ohm's law for bulk resistivity. This includes heat flow, some optics and some aspects of Newtonian mechanics. It is not usually applicable to fluid dynamics, owing to viscosity and compressibility effects, or to high-intensity optics where non-linear effects become apparent. It may be applicable to some mechanical problems involving homogeneous and isotropic materials such as metals, but not to composites.
Before the use of Teledeltos, a similar technique had been used for modelling gas flows, where a shallow tray of copper sulphate solution was used as the medium, with copper electrodes at each side. Barriers within the model could be sculpted from wax. Being a liquid, this was far less convenient. Stanley Hooker describes its use pre-war, although he also notes that compressibility effects could be modelled in this way, by sculpting the base of the tank to give additional depth and thus conductivity locally.
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Teledeltos AI simulator
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Teledeltos
Teledeltos paper is an electrically conductive paper. It is formed by a coating of carbon on one side of a sheet of paper, giving one black and one white side. Western Union developed Teledeltos paper in the late 1940s (several decades after it was already in use for mathematical modelling) for use in spark printer based fax machines and chart recorders.
Teledeltos paper has several uses within engineering that are far removed from its original use in spark printers. Many of these use the paper to model the distribution of electric potential and other scalar fields.
Teledeltos provides a sheet of uniform isotropic resistivity. As it is inexpensive and easily cut to shape, it may be used to make resistors of any shape needed. The paper backing is an insulator. These shapes are usually made to represent or model real-world examples of a two-dimensional scalar fields, such as an electric field, or other fields following the linear distribution rules.
The resistivity of Teledeltos is around 6 kilohms / square. This is low enough that it may be used with safe low voltages, yet high enough that the currents remain low, avoiding problems with contact resistance.
Connections are made to the paper by applying areas of silver-loaded conductive paint and attaching wires to these areas, often with spring clips. Each painted area has a sufficiently low resistivity (relative to the carbon) and to be assumed to be a constant voltage. With the voltages applied, the current flow through the sheet will emulate the field distribution. Voltages may be measured within the sheet by applying a voltmeter probe (relative to a known electrodes) or current flows may be measured. As the sheet's resistivity is constant, the simplest way to measure a current flow is to use a small two-probe voltmeter to measure the voltage difference between the probes. As their spacing is known, and the resistivity, the resistance between them and (by Ohm's law) the current density may be determined.
A sheet that is large in comparison to the experimental area is usually sufficient for modeling an infinite field.
Although the modelling of electric fields is itself directly useful in some fields such as thermionic valve design, the main practical use of the broader technique is for modelling fields of other quantities. This technique may be applied to any field that follows the same linear rules as Ohm's law for bulk resistivity. This includes heat flow, some optics and some aspects of Newtonian mechanics. It is not usually applicable to fluid dynamics, owing to viscosity and compressibility effects, or to high-intensity optics where non-linear effects become apparent. It may be applicable to some mechanical problems involving homogeneous and isotropic materials such as metals, but not to composites.
Before the use of Teledeltos, a similar technique had been used for modelling gas flows, where a shallow tray of copper sulphate solution was used as the medium, with copper electrodes at each side. Barriers within the model could be sculpted from wax. Being a liquid, this was far less convenient. Stanley Hooker describes its use pre-war, although he also notes that compressibility effects could be modelled in this way, by sculpting the base of the tank to give additional depth and thus conductivity locally.