This circuit was found in an American magazine 73 for radio amateurs of the 80s. It is an automatic transmission circuit for telegraphy. The circuit is TTL.
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...
The load current can be adjusted up to about 1 A. The transistor can be TIP32 or TIP42. The...
This oscillator with common general-purpose transistors appeared in Radio Electronics magazine in...