The techometer also called revolution counter is an instrument that measure the speed of a rotating machinery. Generally these measurements are rated in revolutions per minute (R. P. M). In this project we have decided to make our own sensor using a led as light source and a photo diode to pick up the pulse. A arrangement has to be made to make a sm
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all hole about 5mm near to the outer surface of the wheel. Led or any light source is fixed to the one side of the rotating wheel and photo diode to the other side of the wheel. Light will fall on the photo diode when the hole on the rotating wheel comes in line with the photo diode and light source or led. This way a pulse is picked up every revolution. Resolution can be increased by increasing number of holes in one cycle. Above is the circuit diagram of sensor circuit. In our actual sensor circuit we used a photo diode instead of photo transistor as photo diode was much easily available in market. It is basically a type of proximity sensor which gives a HIGH output when there is no obstacle between LED and photo diode and gives a LOW when there is an obstacle. Now whenever Infrared rays fall on photo transistor or photo diode free electrons and holes are produced. This leads to increase in current and thereby reducing the voltage at pin number 2 of op-amp (operational amplifiers). When no infrared rays are incident on photo transistor or photo diode current reduces thereby increasing the voltage at pin number 2 of op-amp. The expression for voltage at pin 2 is: Vcc * { Rsensor / (Rsensor+R1) } Rsensor is resistance of sensor, which is low when light false on it otherwise it is high. The value of R1 should be carefully chosen to obtain considerable voltage swing in output voltage. We also use a TTL level convertor which...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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