This circuit was obtained from an American 80's documentation. The balanced mixer can be shown in CB4234. The circuit is for controlling RF signals in a modulation system.
The frequency of this astable depends on the capacitor that can be changed over a wide range of...
This circuit is from a documentation from the 90s. The transistor can be any general-purpose FET...
In the figure we have one of the many options found in this section for an intercom using ordinary...