Category «RF and Video»

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 …

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 …

LM1201 Video Amplifier with Balanced (Bi-Phase) Output

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 …

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: …

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 …

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 …