This article discuss how you can detect the entry of a person in a room and get this signal inside your MCU. This is NOT a complete project but just an idea that can be implemented in many different projects. The technique is to use use an IR transmitter and a receiver pair. One side of door will have an IR Transmitter and the other side of door w
Click here to download the full size of the above Circuit.
ill have an IR Receiver. The transmitter (Tx in short) will continuously send IR beam to the receiver, as long as the receiver(Rx in short) will receive this beam it will give a voltage output in range of 2. 5v to 3. 0 volts. But as this beam is obstructed, for example by someone entering the room, the receivers output will tend towards 4. 5 The IR Transmitter can be made on a small PCB as shown below. It has four mounting holes to fix it in the wall near the door. Please use 1 Watt resistor for R2 and R3 (22ohms). As you can see the optimal distance between the transmitter and receiver is 2. 0ft. to 3. 5ft. While the Rx/Tx should be mounted at the height of 3. 5ft. from the ground. Many people would ask why I have used photo transistors and not modulated IR receivers like TSOP1738 etc. The reason is that the TSOP series sensors were designed for data transfer, mainly from hand held remote control to devices like TV`s or DVD players. So following points were kept in mind while designing TSOP sensors. Maximum range (So that remote could be easily operated in big rooms), since these have long range you cannot assume that only the rays that are directly incident on the Rx are the only rays reaching it, rays bounced from walls also reach the sensor. So actually their are more than one path from the Tx to Rx. This makes door entry detection impossible because if the person entering the room cuts one path, the ray would reach...
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.....
characters left: