With this circuit it is possible to tune an AM signal using a 5k potentiometer (4k7). The circuit was found in a publication from the 1980s and the PLL can be replaced by an equivalent one, with tests.
This low-power intercom can be powered by solar cells. The circuit is two-way, with an integrated of the...
Reversing the switching action, with the output going high when the input is low, can be done by...
This converter was found in the June 1991 issue of Radio Electronics magazine. The circuit uses...