Not necessarily. You can imagine the transistor stage also as prebiased switch. It don't need to amplify the input signal undistorted. So I think, the circuit is O.K, if the sensitivity is sufficiant. Your right of course regarding the wallpaper circuit.the value of 4.7M is much too high
Audioguru said:The "amplifier" transistor in the photo does not have a base bias resistor.
But then the original circuit doesn't either because the value of 4.7M is much too high.
The suggestions are basically simple and most likely insufficient for a selective detection, as addressed by Audioguru. You have to specify the intended grade of selectivity for your project. If you imagine similar percussive sounds like hammer blows, clapsticks, hail on a tin roof, popcorn making, marbles clicking, which can be sorted out?The suggestions also seems hard for me to understand.
Can be a starting point I think. I suggest. that you start to evaluate the characteristics of hand clapping and other percussive sounds. All you need is a computer with a souncard, a microphone and some sound recording and processing software. I used CoolEdit at times, but there are much other powerful products, also good ones in the public domain. The software can record sounds, display the waveform in time domain and it's frequency spectra, perform filtering and dynamic processing.So in order to filter out low frequency, i should design a high pass filter?
The extremely simple circuit already has a highpass filter as explained in its article: "The output of the (transistor) amplifier is converted to a sharp pulse by passing it through a (relatively) low valued capacitor, of 0.1 microfarads (100 nanofarads)".So in order to filter out low frequency, i should design a high pass filter?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?