This small source for low consumption projects was found in an old national documentation. The transistor is for general use and the transformer has 50 to 100 mA of secondary current.
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...