Capacitor in series in an audio circuit: High pass filter.

Capacitor in series in an audio circuit: high pass filter. A variable audio oscillator is hooked to a RC circuit. The circuit passes high frequencies and blocks low frequencies, and can be observed with an oscilloscope or speaker. Capacitance and resistance can be varied. A good set of starting values is 1 micro f capacitance, and 15 ohms resistance. Maximum signal is at 20 KHz; signal is attenuated by 50% at 760 Hz (6 db down); and by 90% at 260 Hz (20 db down). Closing or opening the key-switch allows one to check the frequency attenuation. Short the capacitors before putting away speaker. CAPACITANCE.