This low current source without a transformer is intended for applications where insulation is not important. The circuit has a 110 V (120 V) input and was found in old American documentation.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...