| 摘要 |
PURPOSE:To attain a frequency change over a broad range by using a transistor (TR) as a feedback resistor of an astable multivibrator and applying a modulation input to a base of this TR. CONSTITUTION:The oscillating frequency of the astable multivibrator 14 is decided by capacitance values of capacitors C12, C13, a feedback resistor R and 5 resistance value of the conduction resistance of a TR15 and the oscillating frequency is changed optionally by changing a base voltage of the TR15 so as to change a resistance between the collector and emitter. When the level of an input signal is larger, the resistance between the collector and emitter of the TR15 is decreased, the collector current is increased, the charging time constant of the capacitor C13 via the TR15 is decreased and the oscillating frequency of the astable multivibrator 14 is increased accordingly. |
