This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
This circuit applies to an old dial phone by detecting light pulses in the dial. The circuit is...
In the figure we have an interesting circuit for those with a project that requires a sub-multiple...
Figure bellow shows how the 4510 can be cascaded for counts higher than 10. The circuit shows the...