Demonstration apparatus for self-exited vibration

The utility model relates to a self-oscillation demonstrating device which belongs to an educational affiliation. The self-oscillation demonstrating device relates to the improvement of the self-oscillation demonstrating device during middle school physical class education. The utility model just provides a self-oscillation demonstrating device which can demonstrate single resonant self-oscillation and also can demonstrate multi-resonant self-oscillation. The self-oscillation demonstrating device comprises a demonstrating board. In the structural key points, the demonstrating board is provided with a luminous diode LED1 and a loudspeaker; an anode of a battery set is connected with a cathode of the luminous diode LED1 by a slide rheostat R3 and a switch K1; the anode of the luminous diode LED1 is connected with a collector of an audion VT1; the emitters of the audion VT1 and the audion VT2 are connected with the cathode of the battery set; a base electrode of the audion VT1 is connected with the cathode of th