Digital & Analog Based Mini electronics Projects Page_6

Digital & Analog Based Mini electronics Projects Page_6

51. Intelligent Switch:

This intelligent switch circuit enables automatic, switching on of an emergency light system during darkness in the event of mains failure.

52. IR Music Transmitter And Receiver:

Using this circuit, audio musical notes can be generated and heard up to a distance of

10 meters. The circuit can be divided into two parts: IR music transmitter and receiver. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V.

53. Knock Alarm:

This circuit used in conjunction with a thin piezoelectric plate, senses the vibration generated on knocking a surface (such as a door or a table) to activate the alarm. It uses readily available, low-cost components and can also be used to safeguard motor vehicles. The piezoelectric plate is used as the sensor. It is the same as used in ordinary piezobuzzers and is easily available in the market.           

54. Laser Communication System:

This laser communication system transmits sound or music signals through a laser beam. The intensity of the laser beam changes with the amplitude of the sound signal. The variation in the intensity of the laser beam is converted into a variation in the voltage level by using a calculator’s solar panel.

55. Led Lighting For Christmas:

Using light effects for decoration on festive occasions is a normal practice. Designers are

coming up with varieties of electronic circuits to fill the imagination of users.

56. Liquid Level Alarm:

Here is a simple circuit for liquid level alarm. It is built around two BC547 transistors (T1 and T2) and two timer 555 ICs (IC1 and IC2). Both IC1 and IC2 are wired in astable multivibrator mode. Timer IC1 produces low frequency, while timer IC2 produces high frequency. As a result, a beeping tone is generated when the liquid tank is full.

57. Low Current, High Voltage Power Supply:

A high voltage power supply is a very useful source which can be effectively used in many applications like biasing of gas-discharge tubes and radiation detectors etc. Such a power supply could also be used for protection of property by charging of fences. Here the current requirement is of the order of a few micro amps. In such an application, high voltage would essentially exist between a ‘live’ wire and ground. When this ‘live’ wire is touched, the discharge occurs via body resistance and it gives a non-lethal

 but deterrent shock to an intruder.

58. Low-Power Voltage Doublers:

All miniature electronic devices operate off batteries. Some of them need higher than the standard battery voltages to operate efficiently. If the battery of that specific voltage is unavailable, we are forced to connect additional cells in series to step up the DC voltage. Thus, the true meaning of miniaturization is lost. A simple way to overcome this problem is to employ a voltage doublers, if the device under consideration can operate at a small current.

59. Mains Supply Failure Alarm:

Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark.

60. Midnight Security Light:

Most thefts happen after midnight hours when people enter the second phase of sleep called ‘paradoxical’ sleep. Here is an energy-saving circuit that causes the thieves to abort the theft attempt by lighting up the possible sites of intrusion (such as kitchen or backyard of your house) at around 1:00 am. It automatically resets in the morning.