In the receiver, stereo radio station. Usually, have more noise than listening in mono. Because the stereo system is split signal-to-noise ratio. (S/N) There level lower, cause interference, in mono with less. the because of phase noise of the 2-back phase. When combined into a mono signal was decreased by default.
How Simple audio noise filter circuit works
As a principle, the noise is high frequency, thus if both high frequencies are mixed together. The noise will go out while the sound still normally stereo system.
Figure 1 Noise Filter for Stereo system
Figure 1 includes the emitter common follower output circuit in series (cascade) in each channel. The high-frequency noise in 2 channel will be refuted, by through high pass filer include R3 to R7 and C3 to C5. This frequency is in 8 kHz range. When switch S1 close circuit and S1 open circuit the operation will stop but there are resistors R9 to R11 drop across S1 to maintain DC voltage level for capacitor C3 to C5. Thus when turning on switch S1 no sound “tup” out to the speaker.
The frequency will cut off without changing with add or reduce the value of C3 to C5, which if add capacitance cause frequency be low down.
Audio noise filter circuits using 2N3819 FET
When we said to Noise signal in an audio system. everyone not likes it, wants to get rid of it all. I also not like them too. However, we can use it to get rid of it. I use transistors. Because it is easy to find. And low noise. Friends try to see the circuit below.
Noise Filter Signal using FET 2N3819
This is Noise Filter Circuit for filter the frequency disturbs all well. By using base type equipment the FET transistor number 2N3819 and Electronic part The other a little again. It can be usable economize with. By the circuit will decrease frequency tall signal more 20KHz well. Then can apply inside sound circuit well, and still have still can fine decorate filter noise level has as well.
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