Here is the video amplifier circuit using op-amp. A video signal coming from the video player to connect to others video recorder or the video in of the TV. If we use a long cable to make the weak signals.
Thus, the strength or clarity of the signal is not well. We have to use a signal amplifier to solve this problem.
The circuit in Figure below is simple video amplifier circuit. It uses an op-amp IC: LM359 or similar. Which they can work in a high frequency such as LM3900 series.
Gain bandwidth of the LM359 is approximately 10-100 times at frequency 30MHz range. Also, they can use up to 400MHz, but lower gain.
The principle of simple video amplifier
This op-amp is connected in negative feedback from or non-inverting. Because of has signal is fed to negative polarity. Then, the output signal will be feedback to the negative polarity again. To make a more stable operation.
Although, the gain is reduced. It will raise the bar even higher frequencies in equal proportions.
The gain of the circuit calculated by dividing R3 and R1, around 10 times.
So, it is a gain of approximately 20 dB at the frequency band of 20 MHz.
Resistors-R1 is input resistance value 750 Ohms, to appropriate values to load 75 Ohms. Load on the antenna is 75 Ohms. The R1 value is the specific values at only applies to the number LM359.
If you want to use other op amps. The input impedance can be as high as approximately 20K ohms.
Let’s build this circuit.
This circuit use can assemble on breadboard. Then, solder they on a solderable PC BreadBoard.
The components list
Resistors 0.25W +-5%
C1, C4—0.01uF/50V polyester
Socket IC 14 pin.
Solderable PC BreadBoard
Antenna 75 ohm
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