Mutchus

This is a circuit for emergency lighting with LEDs that uses electricity from the telephone line . Generally the phone line has a DC voltage 48V and somewhere around 20 mA , and when the phone rings , the voltage rises to 96V AC . This works in a way that the phone line will not be busy while the LEDs are turned on and when you pick up the phone , the light goes off and lets you use your phone normally .  Emergency Light using Phone Line Circuit Diagram

Line Follower Robot Sensor Concept - Sensor line detector is used in line follower robot is usually based on the principle of light reflectionto distinguish the line with the background color. In the dark color of the light absorption is greater than that of white light reflected to the sensor becomes smaller. Position sensor to track the trajectory and the example circuit. Line Follower Robot  Sensor  Concept Light used for the introduction of the line is usually visible light and infra-red. Sensors for visible light are commonly used are LDR (Light Depending Resistance), while for the infrared light is atransistor and photo diode (photodiode). Sensors placed at the bottom of the frame to hang the robot, so that its position can be located just above the track to be read.

   A professional suggestion for those interested in improving sound. The circuit constitutes the part of input mixing console sound from the microphone or source of high level . It can be used on it's own or be multiplied to the number of channels required. It includes all the useful functions such as, phantom power , reverse face, signal attenuation for avoiding distortions from high level signals regulating channel gains and the rest of the stages will be added next stages ,for full mixing console. Attention must be paid to the quality of the materials used. This circuit may used, previous to Parametric EQ circuit. Source http://users.otenet.gr/~athsam/mic_line_balance.htm