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.
Found in Motorola documentation from the 1970s, the circuit presented uses a component from the...
This is the circuit of a “follow the line” type robot with inductive sensors published in Radio...
This simple circuit can be used to power a simple communication system using ordinary telephones....