This simple TTL siren was found in a 1980s Electronics Today International. The power supply is 5 V and the integrated circuit can be the 7400.
This circuit from a 1980 publication, converts the temperature sensed by Q1 into a frequency in a...
This oscillator has its frequency controlled by crystal and its frequency can be between 100 kHz...
The author has many books he had written in Eglish (See the Biography) published by famous...