Free electronic circuit design and schematic diagram
FM demodulation can be done with phase locked loop (PLL), and this method is common in high-end communication system. This system uses TC9400 that has high linearity. Using TC9400, the performance of phase-locked loop will increases greatly. That will give very precise tracking of Vout with respect to Fin. Here is the block diagram of the FM demodulation with a […]
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This schematic diagram shows an LM1893 powerline modem circuit. This circuit is used to transfer information between remote location by using the power mains. This circuit uses LM1893 that is used as a power line interface for half-duplex (bi-directional) communication of serial bit stream of virtually any coding. Here is the schematic diagram of the circuit : To give maximum […]
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The circuit diagram below is a simple RS-485 circuit. Full-duplex communications (simultaneous transmission and reception) with only two essential packages (IC2 and IC3) is provided by this circuit. For high-noise environments or for long-distance transmission between a computer and it’s peripherals, the simple RS-485 balanced and differential data lines are necessary. Such transmission are difficult, if possible, using the single-ended […]
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A PLL system can be used to implement an FM demodulator. When a PLL is locked on an FM signal, the VCO tracks the instantaneous frequency of that signal. Since the VCO output tracks the FM signal, and the VCO input voltage is proportional to the VCO output frequency, then the VCO input will be equal to the demodulated signal. […]
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A split-phase data signal consists of a series of binary digits that occur at a periodic rate, as shown in waveform A in the timing chart. The weight of each bit, 0 or 1, is random, but the duration of each bit and, therefore, the periodic bit rate, essentially is constant. A clock that is synchronized with the data bit […]
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This FSK demodulator convert the FSK signal to serial digital signal. FSK modulation is used to transmit digital serial data, and we need to demodulate it to get back the digital data at the receiver. Here is the schematic diagram of the circuit: This demodulator circuit uses 2225/2025 Hz for mark/space coding, and this frequency is the answering frequency of […]
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This radio modem is popular for amateur radio packet application. This radio modem is powered by the data and control lines, so it need no additional power supply. Just plug to your standard RS232 port and this modem will work. As seen in our previous modem circuit, this radio modem circuit also uses TCM3105 modem chip from Texas Instruments. To […]
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