This circuit is presented as an alternative to the IR beam break detector featured in the June 2009 issue (Silicon Chip). In order to make it relatively insensitive to ambient light, it uses a standard IR receiver IC such as the Jaycar ZD-1942. This has a high output (+5V) as long as a modulated beam is detected. The IR detector (IC3) controls an
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LM 7555 CMOS timer (IC2) which operates in mono stable mode. When the beam is broken, IC2 is triggered and its pin 3 output goes high for about half a second. This extinguishes LED1 and turns on transistor Q1 to drive a 5V low-power relay. The circuit is powered from six AA cells and a 78L05 5V regulator (necessary for the receiver IC). The IR transmitter is also built around an LM7555 (IC1), this time operating in astable mode at low duty cycle. Its frequency is set to 38kHz with trimpot VR1. The IR diode was salvaged from a defunct remote control but these are readily available new. The transmitter is powered by four AA cells. The system has a range of several metres and while it is insensitive to the transmitter alignment, the detection window can be narrowed by placing the detector near to the object to be detected and/or using some form of baffle to restrict the window.
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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