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We can hookup our moisture sensor to the circuit above instead of the velostat sandwiched between two electrodes. | We can hookup our moisture sensor to the circuit above instead of the velostat sandwiched between two electrodes. | ||
[https://www.youtube.com/watch?v=DT6nZsixP0M Here] is a video showing how to build a moisture sensor. [https://ciat-lonbarde.net/tocante/index.html Ciat Lonbarde's Tocante] instrument might use this simple technique to sense touch. | [https://www.youtube.com/watch?v=DT6nZsixP0M Here] is a video showing how to build a moisture sensor. [https://ciat-lonbarde.net/tocante/index.html Ciat Lonbarde's Tocante] instrument might use this simple technique to sense touch. | ||
By replacing the velostat or moisture sensor with a Light Dependent Resistor (LDR) you can use the same circuit to detect ambient light variations. | |||
[http://www.falstad.com/circuit/circuitjs.html?ctz=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-dAwN6mN7hN6wNBgf74z6fbCkxVHZx8NmJLK0I5PSBML7k0GQz7wzAozG4wmM96S2nYBmHZBaHgZm7hJh6kWo9MyxgqZWI1jMARkuHa-Hk1Hm5FQfjlzFkP72HSCdhnAwEDZQWr6pAANY6AD8LGoEhsADEILQxrzFRAb7JFCoNCwgA Frequency Detector] | [http://www.falstad.com/circuit/circuitjs.html?ctz=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-dAwN6mN7hN6wNBgf74z6fbCkxVHZx8NmJLK0I5PSBML7k0GQz7wzAozG4wmM96S2nYBmHZBaHgZm7hJh6kWo9MyxgqZWI1jMARkuHa-Hk1Hm5FQfjlzFkP72HSCdhnAwEDZQWr6pAANY6AD8LGoEhsADEILQxrzFRAb7JFCoNCwgA Frequency Detector] | ||
Revision as of 15:26, 19 January 2023
This page shows a few ways to sense touch or force and convert it to an analog voltages.
1V/Oct analog keyboard interface
This is a vintage style analog keyboard interface that is used e.g. on the stylophone to convert touches to pitches in 1V/Oct. More sophisticated version with note priority and touch/release detection can be found on music from outer space.
Velostat Pressure Sensor / Moisture-to-Voltage converter
This circuit can be used to detect finger pressure or any force on a surface with the help of a pressure sensitive sheet material called 'velotstat'. You can find a tutorial how to build the physical sensor here.
The same circuit can be used with a different type of physical interfaces as well. Instead of the velostat material as a variable resistor we can use a layout of wires known as a 'moisture sensor'. We can hookup our moisture sensor to the circuit above instead of the velostat sandwiched between two electrodes. Here is a video showing how to build a moisture sensor. Ciat Lonbarde's Tocante instrument might use this simple technique to sense touch.
By replacing the velostat or moisture sensor with a Light Dependent Resistor (LDR) you can use the same circuit to detect ambient light variations.
To convert the frequency of a musical signal to a voltage, we can use this relative simple frequency detector circuit. Note that the output is linear in frequency, so it won't match the 1V/oct input of an analog synthesizer. That means pitches will be out of tune. Their might be ways to remedy this by using a logarithmic amplifier instead of the linear amplifier in the schematic. This is shown by the next schematic.