We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the power supply which can consist of 4 batteries or a 9V battery. The basic circuit uses two-color LEDs.
In the figure we have a configuration that allows to test NPN transistors and with the addition of a...
This circuit can be designed with ease today, as its components are common. We found it in old...
This siren produces an intermitent sound given by the characteristics of the two oscillators using the...