Free electronic circuit design and schematic diagram
The transmitters that either working in FM or in AM is familiar. This is transmitters circuit that can transmit both FM and AM signal simultaneously at two different frequencies FM in 100Mhz and Am in 20 MHz. Here is the circuit: To transmit the FM signal, this circuit uses the 5th harmonics of the fundamental 20Mhz. So the range of […]
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This is a FM Transmitter circuit. This circuit uses logic gates. This transmitter circuit has a RF oscillator. This oscillator uses 10.7Mhz ceramic filter and inverter N2 to drive the parallel combination of N4 to N6 through N3. Here is the circuit: The output impedance will be low because these inverters are in parallel, so an aerial of 1/4h wavelength […]
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Twisted-pair wiring is a wiring technique that usually used for in-building data communication. Compared to conventional coaxial-cable, this technique offers substantial cost saving, for video transmission on the same medium. A differential driver is used to launching a baseband camera signal to twisted pair. Twisted pair exhibits a roll-off characteristic that need equalization to correct for. The differential driver and […]
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In some PLL application, sometimes we need to provide lock indication when the PLL is in locked state. The simplest one is binary indication, 0 or 1 to correspond with lock/unlock condition. This condition should be easy to be presented with a LED lamp. The schematic diagram shows a lock-detection scheme for the CD4046B. The PLL system uses phase comparator […]
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Transducers is used in video system to convert optical signal to electrical signal in the acquisition. In the display, transducer is used to convert electrical signal back to light. Transducers often have a transfer function (the ratio of signal in to light out) that is unacceptably nonlinear. The newer technology of video camera transducers (the improved versions of vidicon-like tubes […]
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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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Fading a video signal is not as simple as attenuating the whole signal, since there will be a point where the sync amplitude becomes too small.
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