Small TV Modulator Using A Motorola MC1374

How can television modulator be small and simple like this? First, it uses integrated circuit, and the second, any TV modulator is nothing more than amplitude and frequency modulator. This simple circuit employ a Motorola MC1374 integrated circuit to form a small TV modulator.  To protect unwanted interference, this circuit need a shielded box and outboard circuitry.  The coil L1 […]

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Frequency Modulated Oscillator (for FM Transmitter)

An oscillator can be built using LC (inductor-capacitor) tank circuit. When we vary the capacity of the capacitor in LC tank circuit then the frequency of the oscillator will vary according to capacitance change.  The idea of this modulator is by employing a varactor (voltage-dependent variable capacitor) in the LC tank circuitry. As the capacitance is controlled by a voltage […]

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Amplitude Modulator with OTA

Circuit described in the schematic diagram below can achieve 99% modulation easily with maximum frequency of 200kHz. The amplification of this circuit can be controlled easily since the transconductance of an operational transconductance amplifier is directly propotional to the control current Iabc. The product from input voltage times the transconductance is the output current of this circuit. Here is the […]

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