Showing posts with label Controlled. Show all posts
Showing posts with label Controlled. Show all posts
Wednesday, November 5, 2014
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 mi-nor alterations or fabricate it yourself as shown in Fig. 1.
Fig. 1: Proposed cell-phone holder The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.
Fig. 2: The circuit of the cell phone-controlled audio/video mute switch When the cell phone is in its holder, LDR1 does not receive any light from white LED1 and its resistance is high. As a result, the voltage at pin 2 of IC1 re-mains high to provide a low output at pin 3. The low output of IC1 activates relay RL1 and the audio/video system gets power supply via its N/O contacts. LED3 glows to indicate that the audio/video system is ‘on.’ When the handset is taken off the holder, light rays from LED1 fall on LDR1 and its resistance decreases.
As a result, the voltage at pin 2 of IC1 de-creases to provide a high output at its pin 3. The high output of IC1 deactivates relay RL1 and the audio/video system does not get power supply. LED2 glows to indicate that the audio/video system is ‘off.’ Preset VR1 is used to control the sensitivity of the circuit. Zener diode ZD1 is used for protecting white LED1 from the higher voltage. The circuit works off a 12V car battery. Switch S1 can be used to manually switch on/off the audio/video system.
Monday, October 13, 2014
2051 based ROBOT Controlled Line Follower circuit
This Robot use two motors control rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of comparator, LM324 is low logic and the other the output is high.
Microcontrollor AT89C2051 and H-Bridge driver L293D were used to control direction and speed of motor.
Fig 1. Circuit diagram of my Robot.
Fig 2. Circuit diagram of Infrared sensors and comparators.
Fig 4. Position of sensors, left hand side is side view and right hand side is top view.
Software Software for write to AT89C2051 is robot1.hex ,which was written by C-language ,the source code is robot1.ccompiled by using MC51 in TINY model with my start up code robot.asm .
Subscribe to:
Posts (Atom)