| One application
of the bargraph can be seen on the front of Hi-Fi amplifiers, where an
array of LED's indicates audio levels.
As the signal increases, the LEDs come on in ascending order. The LM3914 has
a linear output, an increase of each 0.125 volts causes another LED to
light up.
The LM3915 has
a logarithmic scale.
As shown, the display is in "bar mode". Change to "spot mode" by disconnecting pin 9 from the positive supply and allowing it to float free. These devices
can be used to sound an alarm when the input voltage rises to a certain
value, or switch larger lamps via thyristors.
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