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This is the Simple Relay Output Proximity Sensor Circuit Diagram. In This Circuit Ql is used as an oscillator around 300 kHz. R9 is set so that the oscillator just begins to run. An object ne ar the antenna will load the circuit down, and stop the oscillations. This is detected by buffer Q2, diodes Dl and D2, and this activates relay driver Q4, which operates the relay.  Simple Relay Output Proximity Sensor Circuit Diagram

A DTMF -based IR transmitter and receiver pair can be used to realise a proximity detector. The circuit presented here enables you to detect any object capable of reflecting the IR beam and moving in front of the IR LED photo detector pair up to a distance of about 12 cm from it. The circuit uses the commonly available telephony ICs such as dial-tone generator 91214B/91215B (IC1) and DTMF decoder CM8870 (IC2) in conjunction with infrared LED (IR LED1), photo diode D1, and other components as shown in the figure. A properly regulated 5V DC power supply is required for operation of the circuit. The transmitter part is configured around dialer IC1. Its row 1 (pin 15) and column 1 (pin 12) get connected together via transistor T2 after a power-on delay (determined by capacitor C1 and resistors R1 and R16 in the base circuit of the transistor) to generate DTMF tone (combination of 697 Hz and 1209 Hz) corresponding to keypad digit “1” continuously. LED 2 is used to indicate the tone output ...

Proximity Detector Circuit Diagram. This proximity detector is constructed using an infrared diode detector. Infrared detector can be used in various equipment such as burglar alarms, touch free proximity switches for turning on a light, and solenoid-controlled valves for operating a water tap. Briefly, the circuit consists of an infrared transmitter and an infra-red receiver (such as Siemens SFH506-38 used in TV sets).   The transmitter part consists of two 555 timers (IC1 and IC2) wired in astable mode, as shown in the figure, for driving an infrared LED. A burst output of 38 kHz, modulated at 100 Hz, is required for the infrared detector to sense the trans mission; hence the setup as shown is required.  To save power, the duty cycle of the 38kHz astable multivibrator is maintained at 10 per cent.  The receiver part has an infrared detector comprising IC 555 (IC3), wired for operation in monostable mode, followed by pnp transistor T1. Upon reception of infrared signals,...

This proximity detector using an infrared detector (Fig. 1) can be used in various equipment like automatic door openers and burglar alarms. The circuit primarily consists of an infrared transmitter and an infrared receiver. Fig. 1: IR proximity detector The transmitter section consists of a 555 timer IC functioning in astable mode. It is wired as shown in the figure. The output from astable is fed to an infrared LED via resistor R4, which limits its operating current. This circuit provides a frequency output of 38 kHz at 50 per cent duty cycle, which is required for the infrared detector/receiver module. Siemens SFH5110-38 is a much better choice than SFH506-38. Siemens SFH5110-38 is turned on by a continuous frequency of 38 kHz with 50 per cent duty cycle, whereas SFH506 requires a burst frequency of 38k to sense. Hence, SFH5110-38 is used. The receiver section comprises an infrared receiver module, a 555 monostable multivibrator, and an LED indicator. Upon reception of infrared si...

Theory of Capacitive Proximity Sensors | How Capacitive Proximity Sensors Works? This knowledge of Sensors will help you better understand customer applications. In addition, you will be better able to describe products to customers and determine important differences between products. You should know Basics of Electricity and Basics of Control Components before attempting Sensors.  Today we learn the Theory of Capacitive Proximity Sensors and how they work? Let’s Start. Capacitive proximity sensors are similar to inductive proximity sensors. The main difference between the two types is that capacitive proximity sensors produce an electrostatic field instead of an electromagnetic field . Capacitive proximity switches will sense metal as well as nonmetallic materials such as paper, glass, liquids, and cloth. The sensing surface of a capacitive sensor is formed by two concentrically shaped metal electrodes of an unwound capacitor. When an object nears the sensing surface it ente...