LM3915 audio power level meter circuit design electronic project
using the LM3915 monolithic integrated circuit can be designed a very simple audio power level meter that senses analog voltage levels and drives ten LEDs, LCDs or vacuum fluorescent displays, providing a logarithmic 3 dB/step analog display.
One pin of the LM39145 changes the display from a bar graph to a moving dot display. LED current drive is regulated and programmable, eliminating the need for current limiting resistors.
The whole display system can operate from a single supply as low as 3V or as high as 25V.
Replacing conventional meters with an LED bar graph results in a faster responding, more rugged display with high visibility that retains the ease of interpretation of an analog display. LED brightness is easily controlled with a single pot.
The internal 10-step divider is floating and can be referenced to a wide range of voltages
If you'll use this circuit for a 4 ohms speaker R1 should be 10k , 18k for 8 ohms and 30k for 16 ohms load .