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I had previously used the Adafruit TFT display using my library (ported from the Adafruit Arduino library). I decided to optimize the library to improve drawing speed. The same display I use comes with a 4-wire resistive touch-screen as well. I decided to write a simple library for the touch-screen and give Protothreads a try. To incorporate all this, I thought it would be cool if I used these to make a simple game. Tic-tac-toe came to mind as a fun little demo. I'm sure everyone's familiar with the game so I won't explain the rules there. The touch-screen is simply two resistive sheets placed on top of each other on top of the TFT screen. When it is pressed down at a given place, the two sheets make contact and a voltage divider is formed. Using the IO's and the ADC, this voltage is read in the X and Y directions to register a touch. Here is a very good pictorial depiction of the resistive touch screen (taken from the Atmel AVR341 document ): So in order to read the to...

The series of touch switch or touch switch is built by IC NE555, a series of touch switches can be used to turn on lights, alarms or other electronic equipment. This circuit uses 2 pieces of metal plate media as touch, MP1 (Metal Plate 1) and MP2 (Metal Plate 2). Touch switch circuit is equipped with a visual LED indicator for relay status (load active). To enable (Relay ON) can be done by touching the surface of MP1 and to turn it off by touching the surface of the MP2. MP1 and MP2 in touch this switch can use a small piece of copper (diameter 5mm) was enough. Touch Switch series with NE555. Component List 555 touch Switch R1 = 3.3M R2 = 3.3M R3 = 10K R4 = 1K C1 = 10nF-63V D1 = 1N4007 D2 = Red LED Q1 = BC547 IC1 = NE555 RL1 = 12V Relay

TOUCH SWITCH 1 This circuit detects the skin resistance of a finger to deliver a awfully tiny current to the super-alpha try of transistors to show the circuit ON. The output of the "super transistor" activates the BC 557 transistor. The voltage on the highest of the world is passed to the front of the circuit via the 4M7 to require the place of your finger and also the circuit remains ON.  To turn the circuit OFF, a finger on the OFF pads can activate the primary transistor and this may rob the "super transistor" of voltage and also the circuit can close up. TOUCH SWITCH-2 This circuit detects the skin resistance of a finger to show the circuit ON for concerning one second. The output are often taken to a counting circuit. The circuit consumes no current when in quiescent mode:

            It is becoming increasingly difficult for users to interact with the slew of portable gadgets they carry, especially in the area of text entry. Although miniature displays and keyboards make some portable devices, such as cell phones and PDAs, amazingly small, users’ hands do not shrink accordingly.             To solve this problem, we proposed a Virtual Keyboard. This device will replace a physical keypad with a customizable keyboard printed on a standard A4 size paper whose “keystrokes” are read and translated to real input. This virtual keyboard can be placed on any flat surface, such as desktops, airplane tray tables, kitchen counters, etc. and can theoretically be interfaced with any computing device that requires text entry. This would eliminate the need to carry anything around and also prevent any chance of mechanical damage to the keypad in harsh environments if a simple lamin...

This is a simple Electronic Touch Triggered Bistable Circuit Diagram . This circuit uses a 555 timer in the bistable mode. Touching T2 causes the output to go high; D2 conducts and D1 extinguishes. Touching T1 causes the output to go low; D1 conducts and D2 is cut off. The output from pin 3 can also be used to operate other circuits ( a triac controlled lamp). In this case, the LEDs are useful for finding the touch terminals in the dark Cl is not absolutely necessary but helps to prevent triggering from spurious pulses. Electronic Touch Triggered Bistable Circuit Diagram

This electronic touch dimmer circuit can increase the light intensity of incandescent lamps in three steps. Using a CMOS IC TT8486A TT6061A you can build a very simple dimmer circuit which can be used to control intensity of an incandescent lamb by simply touch a contact. Initially, when mains switch is ‘on,’ the bulb is ‘off’. Now, if you touch the touch plate, the bulb glows dimly. On second touch, the bulb gives medium light. At the third touch, the bulb is driven fully and another touch puts off the light. Sensitive Touch Light Dimmer Circuit Diagram: This sensitive touch light dimmer circuit uses minimum external components and can be used for 110V or 220V AC by simply changing some external components . For touch plate, you can use a simple copper plate of 1cm×1cm (a small piece of PCB) or even the end of the lead wire. Touch plate is coupled to the touch detector through 1000pF, 2kV capacitors C4, C5 connected in series. Internally IC TT6061A’s touch signal is connected to the c...

This circuit uses a 555 timer as the bases of the touch switch. You can learn more about 555 timers in the Learning section on my site. When the plate is touched the 555 timer is triggered and the output on pin 3 goes high turning on the LED and the buzzer for a certain period of time. The time that the LED and the buzzer is on is based on the values of the capacitor and resistor connected to pin 6 & 7. The 10M resistor on pin 2 causes the the circuit to be very sensitive to the touch.

The series of touch this switch be an Touch Switch made ​​using FET. This circuit serves to activate electronic devices only when we touch touch sensors. Once we release a touch to the sensor, the electronic device that is connected is turned off again. The series of touch switch or touch switch is very simple, composed only of a FET, resistor and capacitor. The series of touch switches / touch switches work with source voltage 12VDC. Detailed series of touch switches / touch switch can be seen in thethe following figure . FET Touch Switch The series of touch switches / touch switch can only be used to illuminate DC, 12V DC lamp when it replaced the relay, the circuit can be used safely to load the AC network. Sensor touch to this series was made with 2 pieces of plate are arranged close together (within 1-2mm).