The maximum frequency of this circuit is 500 kHz. We found it in a documentation for radio amateurs from the 1980s. The integrated circuit used is uncommon today.
Using bipolar, FETs and unijunction this long-lasting timer can reach 10 hours with good quality...
The configuration shown is from the National Semiconductor Linear Applications Handbook. The...
This shield circuit uses a common CMOS port. The voltage depends on the interfaced logic. The...