We found this configuration in a 1990 Poptronics. The circuit can be powered by voltages between 6 and 15 V, changing the resistors in series with the LED. The frequency is set at R7.
This circuit was published in an article in Electronics Now magazine in October 1995. The circuit...
This circuit was found in a 1926 German publication. It is a crystal or galena (D) receiver. The...
With this configuration, greater power can be obtained from an operational amplifier, thanks to...