In this article I will tell you how to make a very sensitive directional microphone, with which you can pick up weak sounds and listen to them.The microphone consists of a reflector and a headphone amplifier.
The reflector is needed in order to receive a lot of weak signals and direct these signals to one point, where the microphone will be located.I cut the reflector out of a plastic 25-liter bottle of beer.Shielded microphone cable applied from USB cable.
It’s time to find that point with the strongest signal, where the microphone will be located.The signal source is a monotonous generator located half a meter from the reflector.An electret microphone is connected to an oscilloscope or a microphone can be connected to a voltmeter.The point with the strongest signal is found experimentally, but it should almost always be in the very center of the reflector.In the photo, I clearly showed this.
Three-transistor amplifier circuit.The 2sc3199GR transistor is located in the input stage.This is a low-noise transistor, BC547B transistors are also low-noise.The resistor R3 regulates the sensitivity of the amplifier, the headphones with a resistance of 60 ohms serve as a load.Do not use headphones with buttons.
The microphone is located in a bent plate, in this way it picks up more signal from the reflector.
Now it’s time to check the device in the park.Find a bird and point a reflector at it and listen to its singing.
