| 摘要 |
PURPOSE:To obtain alarm sounds which are always attractive and have a wide variety by continuously changing one or more out of the frequency, intermittent frequency and sound volume of the alarm sounds depending upon the changes in ambient temperature or brightness. CONSTITUTION:An astable multivibrator using a thermistor 1 for temperature detection as a constant at the oscillation and CdS2 as a light sensitive element is used as an oscillator. The thermistor 1 and CdS2 and capacitor determine the time constant of the oscillator. As a result, the frequency will be higher as the brightness is higher and the temperature is lower. When control terminal CONTROL is at ''1'' level, AND circuit at NOT circuit form a positive phase amplifier to continue oscillation at the above time constant. |
