More LED in audio level indicator is distracting and not good. In this time we can build a 3 LED based Audio level indicator using two LM358 op amp Ic.
Introduction
The LM3915 was commonly used in Audio level indicator for a long time. However, it is no longer in production, likely because it used outdated manufacturing methods.
Although some sources claim to have genuine ones, there is a risk of receiving unreliable versions. The Samsung KA2284 is an alternative, with a similar function, but it may not be available from major suppliers.
Modern equipment often uses a simpler 3-LED system to indicate signal presence, approaching peak, and overload. There are no specific ICs for this, so the circuit needs to be built using individual components.
Using a PIC or similar device is possible but hasn’t been explored much. The 3-LED system is less distracting than the older 10-LED bar graph and might make it easier to spot overloads.
Circuit Diagram
Working
The circuit works well with just 2 × LM358 dual opamps for one channel. The diagram shows a single channel, but for stereo, you’d usually use two of these circuits side by side.
LM358 opamps are inexpensive and use very little power. The circuit doesn’t try to connect the LEDs in series to reduce current, as there are only three LEDs.
A good circuit lets you adjust levels as needed, and this design allows for that. Even though it might seem a bit complicated with four opamps, it’s a helpful learning exercise, letting you understand how each part of the circuit works by looking at it with an oscilloscope.
| Also Check: Simple VU meter using LM3915 IC
