Archive for the ‘RF and Video’ Category
Voltage Controlled Variable Gain Video Amplifier
This is a video amplifier circuit featured with controllable variable gain. The control is done by adjusting the voltage of grid inputs of two FETs, which are configured as programmable voltage divider. This circuit can generate dynamic linear range attenuation up to 100 dB. This circuit still give a linear attenuation even at f=10.7MHz. You …[Read More]
Double-Sideband Suppressed-Carrier (DSB-SC) Modulator
When we modulate a carrier signal with amplitude modulation, there will be four frequency components as the result. The first is the modulating signal itself, the second is the frequency carrier, the the latest two are the difference and the sum of the carrier and the modulating signal. The spectrum of these frequencies can be …[Read More]
This is a schematic diagram of video amplifier circuit with bi-phase output. Bi-phase output provides both positive-going and negative-going signal, and can be used as balanced signaling. The main component of this circuit is LM1201. In this circuit, the inverted video is obtained at pin 10 because of the 75Ω termination to the power supply …[Read More]
Wideband Buffer using FET and Bipolar Transistor
The schematic diagram shown below is a wide-band buffer circuit. This circuit is formed by FET and transistor. This circuit consist of series-feedback buffer which act as wideband unity-gain amplifier. This wideband unity-gain amplifier has high input impedance due to the low input impedance of 2N5485 FET. Here is the schematic diagram of the circuit: …[Read More]
15 Channels Cascaded MAX455 Video Mux
On this following circuit shown in the schematic diagram, two MAX455s IC chip are cascaded to build a 1 of 15 video Multiplexer. This cascading is done by connecting the output of one MAX455 MUX to one input of a second MAX455 MUX. The output of the first MUX should be terminated to ground using …[Read More]
AM Radio Receiver Circuit Employs FM IC Chip
This AM receiver consists of a TDA7000 single-chip FM receiver (U1) as the main radio component, and an LM386 chip for low-voltage audio-power amplifier (U2) circuit. The receiving coils are hand-wound coils (L1 and L2), and a few additional components. This coils, together with the variable capacitor, is chosen to match the AM frequency. To …[Read More]
Simple 9V Wireless Microphone FM Transmitter
This FM transmitter circuit can be used as a wireless microphone, can be received by an ordinary 88- to 108-MHz FM broadcast receiver. For the power supply, this transmitter circuit is powered by a 9 V battery. To comply with the radiation limit of FCC rules, keep the antenna length under 12 inches. L1 is …[Read More]
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