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Hello, I saw a project here named "TV Signal Amplifier source: smartkit" and it says it will amplify weak tv signal. I was assuming that the purpose of this amplifier is to boost TV signal so that you can watch now an improved reception, correct?

My question: If you amplify the weak TV signal, you will also amplify the noise or raster effect of this weak TV signal. So overall, you still have a very bad reception ?? It does not improve anything. Please clarify...

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If you live anywhere near a TV station then this very simple circuit will be overloaded and won't amplify another weaker station. It is not tuned like the input of your TV.

If you live away from any TV stations then your TV will be operating at its max gain and this very simple circuit won't do anything except amplify its own noise.

If there is only a single TV station that is weak, then this very simple circuit could amplify it at the antenna, to make up for the loss in a long cable from the antenna on the nearby mountain to your TV. Then it is a useful amplifier.

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Hi, thanks for the reply. So this simple signal amplifier is only practical to use if you have one or two tv channels that are weak?

The reason of my inquiry because I have a set-top-box that converts analog tv signal to digital then it is fed to my tv's A/V. The problem is, I have 2 tv channles that are very weak and my set-top-box cannot convert it to digital anymore and it will just show a message "No Signal" for those 2 weak channels. So I am finding a way to boost the tv signal before it is fed to my set-top-box. Any alternative solution for this? Or the best thing is really to boost the signal before it's fed to my STB.

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Look at the datasheet for a 741 opamp.

With 100% negative feedback it has no gain because its output level is the same as its input level up to about 9kHz. Then at higher frequencies its max output level drops because of "slew-rate-limiting" where the output becomes a triangle-wave and it can't "slew" as fast as its input so its amplitude becomes less at higher frequencies. At 1MHz and higher its output level is zero. It is old fashioned.

For audio, I use TL07x opamps that have full output level up to 100kHz. They are inexpensive, come as single, dual and quad, have low distortion and low noise.

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