This circuit is from the 80's, using an integrated of the time. The circuit serves as a reference, as this type of dialing is no longer used today.
This circuit is from an 80's documentation. Equivalent transistors can be used. The circuit is...
The frequency of this traditional crystal oscillator (XTAL) depends only on the used crystal,...
We found this basic mixer with the 741 integrated circuit in a 1992 publication. The battery is...