These were the final version of my audio level meters, used on many audio projects, including audio amplifiers and audio controllers. They have 22 LEDs arranged as two rows of eleven and could be set to display in bar or dot mode.
In the photo, the top set represents the multi-color version of these level meters. Five are green, three are yellow and three are red. The first LED in each row shows power to the meters, and thus is on whenever the meters have power, regardless of whether or not there is a signal. The bottom set shows a single color version of these level meters with some red rectangular LEDs I happened to have in my parts cabinet.
These displays use either the LM3914, LM3915 or LM3916 depending on the application. I still build and sell these units for use in computers and other projects. They come as shown (except with an updated PCB), or using a Bar Graph LED display. LEDs can be color/size of your choice. Line-Level or power output can be measured. Here are a couple of videos showing these audio level meters in action.
Please leave a comment below with any questions, suggestions or feedback.
THIS IS A RESTORED ARCHIVE PROJECT AND AS SUCH MAY BE MISSING PHOTOS, PARTS LIST, SCHEMATIC, ETC.