This nice analog indicator circuit was found in the January 1974 issue of Radio Electronics magazine. The circuit has 8 scales with individual adjustments. The instrument is rated at 50 uA.
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...