ffd

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 s...

NE567  tone decoder / PLL IC. NE567 is a tone decoder IC from Philips. The IC has a built in PLL circuit with AM lock detection and an output driver circuit. The main function of NE567 is to drive a load (usually LED) when a frequency with in its detection band is available at the IC’s input. Center frequency of the input frequency band, output delay etc can be programmed using external components. The features of NE567 IC includes 0.01Hz to 500KHz frequency range, highly stable centre frequency, programmable bandwidth, high noise rejection, can sink 100mA at the output, highly immune to false triggering, externally adjustable VCO frequency etc. The common applications of NE567 are touch tone decoding, remote controls, ultrasonic controls, frequency monitoring etc. NE567 proximity detector circuit.   A simple proximity detector circuit using NE567 is shown here. Pin 8 is the output terminal of the internal output driver circuit inside the IC. This pin goes low when the input f...