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 simple photometer uses a 1 mA milliammeter and a common phototransistor. The circuit has its...
The circuit of the figure allows to implement a multimeter of high sensitivity or even to use a...
This simple circuit must be powered by a voltage of 5 V. The integrated circuit is the 7400, but...