This circuit was found in a 1970 US publication. Transistors are still common and the circuit can be used as a PWM shield or pulse transmission modulator.
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...