This commercial receiver from the year 1958 uses two AA cells as Power supply. The circuit is intend to receive MW station and the transistors are germanium types not easy to find today.
In the figure we have an interface using an optical coupler and the comparator LM339 or any...
Figure below shows the basic configuration of a ringoscillator using CMOS Iogic. The frequency...
In the figure we have the way of modulating or controlling the frequency of a relaxation...