Normally home appliances are controlled by means of switches, sensors, etc. However, physical contact with switches may be dangerous if there is any shorting. The circuit described here requires no physical contact for operating the appliance. You just need to move your hand between the infrared LED (D2) and the phototransistor (Q1). The infrared
Click here to download the full size of the above Circuit.
rays transmitted by D2 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer or else. This circuit is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, D2, phototransistor and other discrete components. When regulated 5V is connected to the circuit, D2 emits infrared rays, which are received by phototransistor Q1 if it is properly aligned. The collector of Q1 is connected to non-inverting pin 3 of IC1. Inverting pin 2 of IC1 is connected to voltage-divider preset R4. Using preset R4 you can vary the reference voltage at pin 2, which also affects sensitivity of the phototransistor. Op-amp IC1 amplifies the signal received from the phototransistor. Resistor R3 controls the base current of transistor BC548 (Q2). The high output of IC1 at pin 6 drives transistor Q2 to energies relay RL1 and switch on the appliance, say, hand dryer, through the relay contacts. The working of the circuit is simple. In order to switch on the appliance, you simply interrupt the infrared rays falling on the phototransistor through your hand. During the interruption, the appliance remains on through the relay. When you remove your hand from the infrared beam, the appliance turns off through the relay. Assemble the circuit on any general-purpose PCB. Identify the resistors...
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: