This circuit was found in documentation from the 1970s. However, it can be implemented with modern transistors such as 2N2222 for Q1 and BF494 for Q2. The crystal depends on the desired frequency.
The 4007 integrated circuit consists of 4 MOSFETs that can be used separately. The figure shows how...
August 2016 - It can be obtained from Mouser Electronics new operational amplifiers with extremely low...
This circuit triggers an alarm in the event of a power failure. The circuit is from an 80's...