The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and 2N2431 can be used. The circuit is from the 80's and makes use of transformers.
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...