This counter was found in the November 19983 issue of Radio Electronics magazine. The power supply can be between 3 and 12 V typically. The counting speed depends on C1.
This typical tone decoder with the PLL NE567 was found in old documentation and can work with...
This circuit for vehicular use is from an 80's American publication. The circuit has a light...
The National Semiconductor LM143 integrated circuit consists of a high voltage operational...