With this indicator you can see how much power an amplifier delivers. The circuit uses a LM 3915, the logarithmic variation of the known LED VU meter IC LM 3914. The circuit is connected directly to the speaker output of the amplifier, and the power state of 0.2 watts to 100 watts. The sensitivity of the circuit can be varied with R1. The basic settings are shown in the table.
- R1 = 10 k (see text)
- R2 = 10 k
- R3 = 390 Ω
- R4 = 2.7 K?
- C1 = 22 V μF/25
- LED1-LED10 = LED (color of choice)
- IC1 = LM 3915