Archive for the ‘RF and Video’ Category
Voltage Controlled Variable Gain Amplifier
This is a circuit of voltage controlled variable gain amplifier. This circuit uses 2N4391 that will provide a low Rds(on) less than 30 Ohm. This circuit also uses a tee attenuator, that will provide optimum dynamic linear range for attenuation. We can obtain the attenuation greater than 100dB at 10MHz by providing proper RF construction …[Read More]
FET Cascode Video Amplifier
This is a simple FET Cascode Video Amplifier circuit. This circuit has some features, they are reduction of feedback to almost zero and very low input loading. Here is the circuit: This circuit uses 2N3823 because it has high Yfs and low capacitance. RL and load capacitance limits bandwidth of the amplifier. [Source: National Semiconductor ...[Read More]
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 …[Read More]
FM Transmitter Using Logic Gates
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 …[Read More]
Twisted-Pair Video Cable Driver and Receiver
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 …[Read More]
PLL Lock Detection
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 …[Read More]
Gamma Correction Circuit
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 …[Read More]
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