This circuit makes use of components from the time it was published. The TCA151 is not a common component today. The circuit generates 10 to 10 kHz signals.
If the battery is good, the LED flashes. This simple tester uses an LM3909 integrated circuit. We found...
This circuit was found in a 1926 German publication. It is a crystal or galena (D) receiver. The...
In the figure we have a typical configuration with operational, which can be different from the...