Digital & Analog Based Mini electronics Projects Page_3

Digital & Analog Based Mini electronics Projects Page_3

21. Cell-Phone-Controlled Audio video Mute Switch:

This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily Available cell-phone holder with some minor alterations or fabricate it yourself.

22. Charge Monitor For 12v Rechargeable 7 Segment Display:

A battery is a vital element of any battery-backed system. In many cases the battery is more expensive than the system it is backing up. Hence we need to adopt all practical measures to conserve battery life.

23. Clap Remote:

An infra-red or wireless remote control has the disadvantage that the small, handy, remote (transmitter) is often misplaced. The sound operated switch has the advantage that the transmitter is always with you. This project offers a way to control up to four latching switches with two claps of your hand. These switches may be used to control lights or fans or anything else that does not produce too loud a sound. To control Multiple Device.

24. Color Sensor:

Color sensor is an interesting project for hobbyists. The circuit can sense eight colors, i.e. blue, green and red (primary colors); magenta, yellow and cyan (secondary colors); and

Black and white. The circuit is based on the fundamentals of optics and digital electronics. The object whose color is required to be detected should be placed in front of the system. The light rays reflected from the object will fall on the three convex lenses which are fixed in front of the three LDRs. The convex lenses are used to converge light rays. This helps to increase the sensitivity of LDRs.

25. Constant Current Battery Charger:

There are many ways of battery charging but constant-current charging, in particular, is popular method for lead-acid and Ni- Cd batteries. In this circuit, the battery is charged with a constant current that is generally one-tenth of the battery capacity in ampere-hours. So for a 4.5Ah battery, constant charging current would be 450 mA. This battery charger has the following features: It can charge 6V, 9V and 12V batteries, Constant current can be set as per the battery capacity, and Battery level indication and the charger will switch off automatically

26. Current Sensor To Notify Device On/Off:

High-wattage appliances like electric irons, ovens and heaters result in unnecessary

power loss if left ‘on’ for hours unnoticed. Here is a circuit that senses the flow of current through the appliances and gives audible beeps every fifteen minutes to remind you of power-’on’ status. This is a non-contact version of current monitor and can sense the flow of current in high-current appliances from a distance of up to 30 cm .

27. Dc Motor Control Using A Single Switch:

This simple circuit lets you run a DC motor in clockwise or anti-clockwise direction and stop it using a single switch. It provides a constant voltage for proper operation of the motor. The glowing of LED1 through LED3 indicates that the motor is in stop, forward rotation and Reverse conditions, respectively.

28. Dice With 7-Segment Display:

Digital dice circuit can be easily realized using an astable oscillator circuit followed by a counter, display driver and a display. In these on seven segments will display 1-6 digit on display as user stop the switch.

29. Digital  Input Selector:

Need to connect more than one audio-video (AV) source to your color television? Don’t

worry, here’s an AV input expander for your TV. It is inexpensive and easy to construct.

30. Digital Speedometer:

This instrument displays the speed of the vehicle in kmph. An opaque disc is mounted on the spindle attached to the front wheel of the vehicle. The disc has ten equidistant holes on its periphery. On one side of the disc an infrared LED is fixed and on the opposite side of the disc, in line with the IR LED, a phototransistor is mounted. IC LM324 is wired as a comparator.