Category: Electronics Projects

The generation of frequency shift keying (FSK) can be easily accomplished by switching an additional capacitor into the tank circuit of an oscillator when the transmitter is keyed, in narrowband frequency shift keying (FSK) it is often possible to get the required frequency shift by shunting the capacitance directly across a crystal, especially if frequency multiplier follow the oscillator, as is usually the case. Circuit Description of Frequency Shift Keying (FSK) Generator Using PLL 565 Frequency shift keying (FSK) can also be generated by applying the rectangular wave modulating signal to…

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The generation of low frequency is generally accomplished with an RC oscillator. The techniques recently developed for frequency synthesis can now be used conveniently with very precise low frequencies required. A low-frequency sine-wave synthesizer well demonstrates accuracy and stability characteristics that can be measured in part per million (even at 0.01 Hz) if it is crystal controlled. Circuit Description of Low Frequency Sine Wave Synthesizer The synthesizer in figure 1 is based on an 8-bit digital-to-analog converter IC AD7523 (IC5) which presents a precise triangle wave to the timing of a…

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A telephone converter circuit that can be used to power the circuit added to the basic phone is shown in figure 1. This may be more economical/convening than adding a separate power supply from the AC power line or using battery power. It takes the -48V provided by the telephone and efficiently converts it to a well-regulated 5V. Circuit Description of Telephone Converter Circuit A telephone converter circuit does not require the bulk and expensive transformer which is usually used in these designs. It takes the -48V (it can function…

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