TOUCH SWITCH/PLATE

INTRODUCTION This Kit combines a Touch Switch and a Touch Plate alltogether in the same Kit. In the Touch Switch two leads must be shorted together by your finger touching them. In the Touch Plate only one plate needs to be touched. The Touch Switch only needs a battery to activate it butthe Touch Plate requires a mains power supply.A Relay rated at 12A/250VAC is included with the Kit sothat you may use to switch a light. To use the relay you must use a 12V supply taken from a mains power supply.

CIRCUIT DIAGRAM

CIRCUIT DESCRIPTION

The main part of the circuit are the two NAND gates of the (1)4011 Integrated Circuit which are connected as a flip-flop. Pins 9 and 13 are the ON and OFF contacts. The two gates are connected to the positive rail by the two10M resistors. Shorting one of the gates with the ground rail by touching it (this is equivalent to connecting about50K between the gate and ground) FLIPs the output tothat state. Shorting out the other contact FLOPs it back.

CIRCUIT DESCRIPTION The output of the flip-flop drives a transistor connected

as a switch. It switches an LED and a relay. The relay is rated to switch 240V. Connecting the two 1K resistors connects the other two NAND gates of the IC into the flip-flop and makes it much more sensitive to touch. The touch plate may in fact work with only the first two

gates connected. But it will be much more sensitive with all four gates connected as a flip-flop. The touch switch works by capacitative pickup of the mains hum.

CIRCUIT DESCRIPTION When the

contact is touched body capacitance picking up general RF in the air is enough to short the plate to ground.

Because the touch plate uses mains hum as it method of

shorting the gate to ground a mains connected power

supply must be used to supply power to the switch. A

battery will not work.

COMPONENTS1K resistor 5% 1/4W brown black red 3 10M resistor 5% 1/4W brown black blue 2 1N4004 diode 1 12V relay Goodsky RWH-SH-112D 1 IC (1)4011 IC 1 14 pin IC socket 1 Hookup wire 4” 5mm LED 1Kit 10 PCBs 2 battery snap 1 BC557 1

RELAY

RELAY

. Main Feature 1. RW Series Relay covers switching capacity by 10A is spite of miniature size to comply with user’s wide selection. 2. RWH is approved C-UL & TÜV safety standard. 3. The employment of suitable plastic materials is applied under high temperature condition and various chemical solutions. 4. Complete protective construction is designed form dust and soldering flux. If required, plastic sealed type is available for washing procedure. 5. 12A at 120VAC for RW & 12A at 240VAC for RWH are UL approved. Application Domestic Appliances, Office Machines, Audio Equipment, Coffee-Pots, Control units, etc.

BC 557

BC 557FEATURES• Low current (max. 100 mA)• Low voltage (max. 65 V).APPLICATIONS• General purpose switching and

amplification.DESCRIPTIONPNP transistor in a TO-92; SOT54

plastic package.NPN complements: BC546 and BC547.

IN 4004

IN 4004 Features • Diffused Junction • High Current Capability and Low Forward Voltage Drop • Surge Overload Rating to 30A Peak • Low Reverse Leakage Current • Lead Free Finish, RoHS Compliant (Note 3) Mechanical Data • Case: DO-41 • Case Material: Molded Plastic. UL Flammability Classification Rating 94V-0 • Moisture Sensitivity: Level 1 per J-STD-020D • Terminals: Finish - Bright Tin. Plated Leads Solderable per MIL-STD-202, Method 208 • Polarity: Cathode Band • Mounting Position: Any • Ordering Information: See Page 2 • Marking: Type Number • Weight: 0.30 grams (approximate)

IC 4011 PIN DIAGRAM

IC 4011

IC 4011

The 4011 is a member of the 4000 Series CMOS range, and contains four independent NAND gates, each with two inputs. The pinout diagram, given on the right, is the standard two-input CMOS logic gate IC layout:

Pin 7 is the negative supply Pin 14 is the positive supply Pins 1&2, 5&6, 8&9, 12&13 are gate inputs Pins 3, 4, 10, 11 are gate outputs The truth table for one of the four gates is shown to the

right. For more infomation about the NAND gate in general, see this module.

This chip is widely available, and usually comes in a DIL-14 or SOIC-14 package.

This chip is different in pinout to the TTL 7400, but can fulfill its function if the wiring is modified.

WHAT TO LEARN FROM THIS KIT

The kit introduces the (1)4011 integrated circuit. Go through the connections of the IC to determine the LOW/HIGH levels as the OFF and ON plates are touched. Notice how connecting the 2 1K resistors increases the sensitivity of the circuit. Y

BUZZER

BUZZERFEATURES• The PS series are high-performance buzzers that employ unimorph piezoelectric elements and are designed for easy incorporation into various circuits.• They feature extremely low power consumption in comparison to electromagnetic units.• Because these buzzers are designed for external excitation, the same part can serve as both a musical tone oscillator and a buzzer.• They can be used with automated inserters. Moisture-resistant models are also available.• The lead wire type(PS1550L40N) with both-sided adhesive tape installed easily is prepared.APPLICATIONSElectric ranges, washing machines, computer terminals, various devices that require speech synthesis output.

WORKINGA touch switch is a type of switch used in many lamps and

wall switches that have a metal exterior.

These devices work using body capacitance, a property of the human body that gives it great electrical characteristics. The lamp keeps charging and discharging its metal exterior to detect changes in capacitance. When a person touches it, it increases the capacitance, and the lamp activates, increases its brightness, or turns off.

(A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch. Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches. Touch switches can be used in places where regular switches would not last, such as wet or very dusty areas.) 

ADVANTAGES

The touch security is cheap in cost and hence can be used for house security at doors.

It is useful circuit for dusty conditions.

It is very useful in rainy conditions.It takes only 100ns to operate

thecircuit.It is used in various applications due

toits quicker response.

Applications

•Doorknob Alarm•Relays•Capacitance to Digital

converter technology….etc

A Presentation by -Mura Lee -Balaji Sundar