This receiver was found in a 1924 book by Gernsback. The circuit uses three tubes and is powered by 3 batteries of different voltages, common at the time.
With the capacitor used, this circuit provides delays of 40 to 60 seconds. Larger capacitors can...
Found in an Electronic Design from the 90's, this circuit generates signals for stepper motor...
The circuit shown in the figure can generate signals up to 1.6 GHz. Coil L1 and capacitor C2 are...