A circuit that can detect a light beam cut. The first circuit i made was a light/dark detector with photoresistor. Although it could sense the light cut, it had a major disadvantage: extreme interferences from ambient light. That is why i designed this simple circuit. I tried to keep it as simple as possible. The maximum distance of the IR LED pair that i used is up to about 2. 5cm (close to 1 inch). That explains the
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title "Short Distance". It has a very good sensitivity. With a potentiometer you can adjust it to sense completely opaque objects, or it can sense semi-transparent films as well! It is also suitable for rotary encoders. It is not suitable for making security systems which require a beam that can go up to 3 or 4 meters long. This is the first part of this IR pair. The transmitter circuit is a pulse generator that drives an infrared LED. I have use the good old 555 chip. The pulses are about 1. 5KHz. You can use of course any kind of pulse generator like an Astable Multivibrator transistor circuit. That is up to you. Here is the schematic for the 555 connected as an astable multivibrator, oscillating at around 1. 5KHz: I began designing a complicated interference-proof circuit, with an active filter and other stages of filtering. Then, i realized that i was going the long way. There is no need for such filtering. This is an IR pair that will be most likely inside a housing, with the transmitter close to the receiver, away from parasitic lights. So, i start removing stages until i got down to minimum. The circuit that follows can be powered with a single 5 volts supply (unlike the other circuits that i designed that required double power supply). It has a simple capacitors filter that drops all constant and low frequency IR light sources such as the sun, the household lighting. The IR detector itself will reject any other...
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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