A frequency counter is an electronic instrument, or component of one, that is used for measuring frequency. Frequency is defined as the number of events of a particular sort occurring in a set period of time. Frequency counters usually measure the number of oscillations or pulses per second in a repetitive electronic signal. Most frequency […]

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Infrared (IR) light is electromagnetic radiation with a wavelength between 0.7 and 300 micrometres, which equates to a frequency range between approximately 1 and 430 THz. IR wavelengths are longer than that of visible light, but shorter than that of terahertz radiation microwaves. Bright sunlight provides an irradiance of just over 1 kilowatt per square meter […]

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The answering machine is a device used for recording telephone conversations as well as automatic answering device. The voice recording machine  is a paradigm of a telephone answering machine. Basically, the system has a recording circuit which store all the messages in ISD9000, and a control circuit which is used to select the messages. ISD1900 ChipCorder series is a […]

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