Machines have been eliminating humans on job tasks for several centuries. As a human being, we definitely need certain actions to be done with a touch instead of pressing buttons. If you are the one looking for such a smart device then here is your halt. In this article, we will be discussing the simple touch sensitive devices which can be used to operate LED or any home appliances.
In simple words, it is a kind of circuit which can be operated or toggled just by a touch. This circuit turns ON and OFF an LED whenever it senses a touch. The best part of this circuit is that very few components are required for the construction. In addition, it is more superior to mechanical switches due to various factors that include:
Touch switches have an infinite life and thus reduce the cost of maintenance.
This switch doesn’t need direct contact with metal and therefore completely eliminates the security risks.
Touch sensitive switch circuit gives a sleeker view to the devices like UPSs, Mixer-grinder.
There are a number of ways to design the circuit by using different microcontrollers, ICs or even with some transistors. Throughout this discussion, we will discuss the design process for some of the simplest touch sensitive circuits that can be easily designed and are cost effective.
Related Post: How to Make a Simple LED Flashing Circuit using 555 Timer IC
Touch-Sensitive Switch Circuit Using 555 Timer IC
To design this highly durable Touch sensitive switch circuit, we are using a 555 Timer IC as the main component. Here, the touch plate triggers the output of the 555 Timer IC, whenever it senses a touch. Before getting started with the design process of this project, let’s give you a quick overview of the 555 Timer IC.
555 Timer IC
The 555 Timer IC generally operates in three different modes depending upon configuration namely A-Stable, Mono-Stable and Bi-Stable modes. This IC is one of the most popular and widely used for providing time delay, as an oscillator or as a flip-flop element. This 8 pin IC is one of the most commonly used IC in electronic components. Go through the below table to understand the different pins and function of 555 Timer IC.
Related Project: PCB Design of LED Flasher Circuit using 555 Timer. Step by step
Gather the following components before starting the design process of the circuit.
Required Components:
555 Timer IC
Touch-Plate (conductive material/Metal)
Capacitors: 10μf, 0.01μf
Resistors: 100 K ohm, 470 ohm
Connecting wires
LED
Circuit Diagram for Touch Switch using 555 Timer
Here, 555 Timer IC is configured in Monostable mode. We can use two pieces of a conductor to make the touch plate, connected with the trigger pin of 555 Timer IC and ground respectively. Pin 5 of 555 timer IC is connected with a capacitor of 0.01 μf. Pin 3 is connected with resistor R2 and Pin 8 is connected with 6V power supply.
Related Project: Clap Switch Circuit Using IC 555 Timer & BC547 Transistor
Working
Whenever we touch the conductive plates of the touch sensor, the 555 Timer is triggered. The output pin goes high turning ON the LED for some time. You can also connect a buzzer in place of the LED. The pulse duration generated at the output pin depends entirely on the timing resistor and capacitor of the circuit connected at pin 6 and 7 of the 555 Timer IC. That means you can change the duty cycle of the output pulse by changing the value of capacitor C1. The disadvantage of the circuit is that it consumes more power.
Simple Touch Sensitive Switch Circuit Using a Transistor
As discussed above, there are a number of ways to design a touch sensitive switch circuit. This touch sensitive switch circuit we are going to discuss now is designed using BC 547 transistor. BC547 is used to amplify the received input signal. In result, the output obtained has extra sensitivity to the input signal. Take a look at brief discussion of BC 547 Transistor given below.
BC547 Transistor
BC547 is an NPN Transistor which allows a maximum of 100mA to flow across the collector and emitter. It has a gain value from 110 to 800. The gain value determines the amplification capacity of the Transistor. We can’t connect loads that consume more than 100mA using BC 547 Transistor. There are two operating regions of the BC547 transistor. When the Transistor is fully biased then this mode of operation is called saturation region. As soon as the base current is removed, the Transistor becomes fully off and this condition is called cut-off region.
Pin number Pin name Description
1 Collector Current flows through the collector
2 Base Controls the biasing transistor
3 Emitter current drains
In electronic circuits, BC547 can be used for switching as well as for amplification purpose, we have also described how BC547 behaves as a switch or an amplifier.
Amplification Using BC547:
The BC 547 transistor acts as an amplifier when operating in Active region. The DC current gainreverse bias. Biasing of Transistor can be done by giving the required amount of current to the base pin. Make sure that there biasing current is not greater than 5mA as the current value greater than 5mA will destroy the transistor. To avoid that situation, a resistor is added in series with the base of Transistor. To calculate the resistance at the base pin, use the formula below.
Browse the list of BC 547 Transistor Applications:
It can be used in Audio amplifiers, Signal amplifier, etc.
It can be used in modules like relay driver, LED driver, etc.
Go through the list of components and gather the items to design the touch-sensitive switch circuit using the BC 547 Transistor.
Required Component
BC547 Transistor
Resistors
6V power supply
Connectors
LED
Machines have been eliminating humans on job tasks for several centuries. As a human being, we definitely need certain actions to be done with a touch instead of pressing buttons. If you are the one looking for such a smart device then here is your halt. In this article, we will be discussing the simple touch sensitive devices which can be used to operate LED or any home appliances.
In simple words, it is a kind of circuit which can be operated or toggled just by a touch. This circuit turns ON and OFF an LED whenever it senses a touch. The best part of this circuit is that very few components are required for the construction. In addition, it is more superior to mechanical switches due to various factors that include:
Touch switches have an infinite life and thus reduce the cost of maintenance.
This switch doesn’t need direct contact with metal and therefore completely eliminates the security risks.
Touch sensitive switch circuit gives a sleeker view to the devices like UPSs, Mixer-grinder.
There are a number of ways to design the circuit by using different microcontrollers, ICs or even with some transistors. Throughout this discussion, we will discuss the design process for some of the simplest touch sensitive circuits that can be easily designed and are cost effective.
Related Post: How to Make a Simple LED Flashing Circuit using 555 Timer IC
Touch-Sensitive Switch Circuit Using 555 Timer IC
To design this highly durable Touch sensitive switch circuit, we are using a 555 Timer IC as the main component. Here, the touch plate triggers the output of the 555 Timer IC, whenever it senses a touch. Before getting started with the design process of this project, let’s give you a quick overview of the 555 Timer IC.
555 Timer IC
The 555 Timer IC generally operates in three different modes depending upon configuration namely A-Stable, Mono-Stable and Bi-Stable modes. This IC is one of the most popular and widely used for providing time delay, as an oscillator or as a flip-flop element. This 8 pin IC is one of the most commonly used IC in electronic components. Go through the below table to understand the different pins and function of 555 Timer IC.
Related Project: PCB Design of LED Flasher Circuit using 555 Timer. Step by step
Gather the following components before starting the design process of the circuit.
Required Components:
555 Timer IC
Touch-Plate (conductive material/Metal)
Capacitors: 10μf, 0.01μf
Resistors: 100 K ohm, 470 ohm
Connecting wires
LED
Circuit Diagram for Touch Switch using 555 Timer
Here, 555 Timer IC is configured in Monostable mode. We can use two pieces of a conductor to make the touch plate, connected with the trigger pin of 555 Timer IC and ground respectively. Pin 5 of 555 timer IC is connected with a capacitor of 0.01 μf. Pin 3 is connected with resistor R2 and Pin 8 is connected with 6V power supply.
Related Project: Clap Switch Circuit Using IC 555 Timer & BC547 Transistor
Working
Whenever we touch the conductive plates of the touch sensor, the 555 Timer is triggered. The output pin goes high turning ON the LED for some time. You can also connect a buzzer in place of the LED. The pulse duration generated at the output pin depends entirely on the timing resistor and capacitor of the circuit connected at pin 6 and 7 of the 555 Timer IC. That means you can change the duty cycle of the output pulse by changing the value of capacitor C1. The disadvantage of the circuit is that it consumes more power.
Simple Touch Sensitive Switch Circuit Using a Transistor
As discussed above, there are a number of ways to design a touch sensitive switch circuit. This touch sensitive switch circuit we are going to discuss now is designed using BC 547 transistor. BC547 is used to amplify the received input signal. In result, the output obtained has extra sensitivity to the input signal. Take a look at brief discussion of BC 547 Transistor given below.
BC547 Transistor
BC547 is an NPN Transistor which allows a maximum of 100mA to flow across the collector and emitter. It has a gain value from 110 to 800. The gain value determines the amplification capacity of the Transistor. We can’t connect loads that consume more than 100mA using BC 547 Transistor. There are two operating regions of the BC547 transistor. When the Transistor is fully biased then this mode of operation is called saturation region. As soon as the base current is removed, the Transistor becomes fully off and this condition is called cut-off region.
Pin number Pin name Description
1 Collector Current flows through the collector
2 Base Controls the biasing transistor
3 Emitter current drains
In electronic circuits, BC547 can be used for switching as well as for amplification purpose, we have also described how BC547 behaves as a switch or an amplifier.
Amplification Using BC547:
The BC 547 transistor acts as an amplifier when operating in Active region. The DC current gainreverse bias. Biasing of Transistor can be done by giving the required amount of current to the base pin. Make sure that there biasing current is not greater than 5mA as the current value greater than 5mA will destroy the transistor. To avoid that situation, a resistor is added in series with the base of Transistor. To calculate the resistance at the base pin, use the formula below.
Browse the list of BC 547 Transistor Applications:
It can be used in Audio amplifiers, Signal amplifier, etc.
It can be used in modules like relay driver, LED driver, etc.
Go through the list of components and gather the items to design the touch-sensitive switch circuit using the BC 547 Transistor.
Required Component
BC547 Transistor
Resistors
6V power supply
Connectors
LED
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