VU Meter

 The Stereo VU Meter PC board with the components fitted. Only the battery and speaker are external, connected to flying leads. A close up of the completed unit. The overlay makes construction easy. Make sure the left-hand row of resistors starts with 47k at the bottom and 4k7 at the top. I saw one unit with the whole row reversed. It made very little difference to the performance of the unit, but it was not quite as sensitive as the correct version

The BOOTSTRAP circuit connects to the LED bar graph via A B C. Only one BOOTSTRAP circuit is provided on the board. It is capable of driving both bar graphs in a mono mode. For a stereo readout, you will need to build another bootstrap circuit. This will give a STEREO SOUND LEVEL INDICATOR.