This circuit that uses potentiometer tuning, was found in a documentation from the 80's. The integrated circuit used is from that time and is a not common today.
This circuit was found in a 1977 documentation. With it we have the direct indication, through LEDs...
In the figure we have the CMOS logic test circuit developed with the 4049. The circuit activates three...
This headlight reminder for your car was found in the May 1970 issue of Radio Electronics...