Simple Capacitive Touch Switch Circuit

A touch switch is a type of switch that only has to be touched by an object to operate.

Simple capacitive touch switch circuit.

The indicated 4 diodes form the basic bridge diode network the thyristor is used for switching the mains 220v ac for the load while the ic m668 is used for processing the on off latching actions whenever the touch switch is touched. What is a touch switch. We can use a general purpose input output pin configured as an output to charge the sensor cap up to the logic high voltage. So you can use them as inputs to do all sorts of fun stuff.

Capacitive switches have clear advantages compared to other types of touch switches for example 50 hz or 60 hz detection or resistance detection but are often more complex to implement. How this simple mains electronic touch switch circuit works. Begin by soldering the ic at the middle of a rectangle 3 3 general purpose board. The first two capacitive proximity sensor circuits uses a simple ic 741 and ic 555 based concepts while the last one is a bit more accurate and incorporates a precision ic pcf8883 based design.

1 touch switch circuit using 555 timer 2 touch toggle switch circuit using nand gate 3 touch switch circuit project 4 touch activated switch circuit 5 a simple touch on and off switch circuit 6 simple touch switch using transistor 6 1 the working principle 6 2 how to builds 6 2 1 the. The construction of this touch sensitive switch circuit can be easily carried out with the help of the circuit diagram through the following simple steps. The circuit playground express and bluefruit have seven capacitive touch pads around the outside labeled a1 a6 and tx. At the heart of the circuit is an inexpensive 20 smd chip ttp223 commonly available in ba 6 package.

An lm339 comparator is used to compare the voltage at point c with a reference voltage d. Simple capacitive touch sensor circuit this voltage is about 2 9 3 2 v when the plate is touched and 2 6 v when it isn t touched. Let s say we have an rc circuit composed of a 1 mω resistor and a capacitive touch sensor with typical fingerless capacitance of 10 pf. Add capacitive touch switch to your projects step 1.

Here is a simple capacitive touch switch circuit for electronics hobbyists. These pads return true if you touch them. Capacitive touch sensors are based on the electrical capacitance of the human body. This effect can be used for proximity detection and touch controlled switching.

Even though the circuit uses smd components construction of the touch sensor switch is not very hard because the whole circuit can be easily fabricated on a piece of smd prototyping board. The latter is set to about 2 8 v using a potential divider. A capacitance switch needs only one electrode to function. Next we need the capacitor to discharge through the large resistor.

The electrode can be.