1.0 Introduction
A touch activated switch as the name implies is a device that is activated whenever a sensation of touch is felt by it through a component of its circuitry.
However, this touch activated switch can be constructed using three different things as sensors which are fully explained below;
- METAL: In this case, two pieces of metals are connected closely to each other and a wire (cable) is connected to each of the metal while the second terminal of one of the wires is connected to a comparator (op-amp) directly which exist as integrated circuits like operational amplifier (op-amp).A sensation of touch is achieved when a finger is touched on both pieces of metal at the same time and a signal is sent via of one the wires to the comparator which will now use the signal to actualize a purpose by switching another device on.
- WIRE: Here, the touch activated switch is realized using two cables as sensor in which one of the cables is directly connected to the sensation decoder. Meanwhile, these cables are connected in such a way that when a finger touches two of them the same time, a signal is sent to the comparator via one of the cables which will in turn activate another device.
- LIGHT DEPENDENT RESISTOR (LDR): this type of sensor is designed with a resistor, in other words it is a type of resistor. In the case of touch activated switch using LDR (sensor), the sensitivity is been determined by a variable resistor. However, using LDR sensor for this kind of project is the best because in this project a high sensitivity is needed. The sensitivity is such that whenever any slite touch is made on the LDR, a signal will be sent to the decoder immediately and the comparator will in turn give an output to switch something on.
There is a Block Diagram Of Touch Activate Switch in the Official Work
Microprocessor
To design an electronic system, one needs to know the difference between a microprocessor and a microcontroller which will enable him to decide which one is the best choice to design an electronic system with.
However, a microprocessor is a central processing unit (CPU) in an integrated circuit which is the core of any microcomputer system. It contains only digital logic circuitry and its most often used to design computers such as laptop and desktop computers.
Meanwhile, a microcontroller is a special-purpose computer system usually programmed to perform a specific task. It is most often used in the design and construction of electronic appliances, automotive electronics and industrial control equipment. Furthermore, a microcontroller contains digital electronics circuitry and analog electronics circuitry.
Finally, a microprocessor operates at a higher speed than a microcontroller. A typical microprocessor will have a clock rate of 1GHZ while a typical microcontroller will have a clock rate of about 20MHZ.
Operational Amplifier (Op-Amp)
An operational amplifier (Op-amp) is a very high gain differential amplifier with high input impedance and low output impedance. In other words an operational amplifier is a solid slate integrated circuit (IC) that uses external feedback to control its functions.
However, an op-amp without any feedback is called “open loop” mode which is actually referring to the so called “ideal” operational amplifier with infinite open-loop gain, input resistance, band width and a zero output resistance. More so, this op-amp has two inputs which are inverting input which is designated by a minus sign (-) and non-inverting input which is designated by a plus sign (+). Meanwhile, these plus and minus signs are not signs of polarity rather they are input terminals.
Furthermore, when the voltage at the two input terminals are the same, the output voltage will be indeterminate. But when the voltage level at the inverting input is greater than the one at the non-inverting input, the output voltage will be low (zero) while when the voltage level at the non-inverting input is greater than the one at the inverting input, the output voltage will be high (VCC).
The material contains electrical diagrams, circuits, illustrations and more (Very detailed)
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