This circuit can easily be assembled on a small piece of prototyping board. Use low-current types for the LEDs. They have a low forward voltage and are fairly bright at current levels as low as 1 mA.

VU (Volume Unit) meters are often included in analog audio equipments to display a signal level in Visual Units. We are building a mono input VU meter in this project. You can build one pair to use ...

Okay, this circuit is really part of the "Knight Rider" project. I have separated it purely for the benefit of web search engines looking for a "Hard Drive Activity Meter". It uses the same basic ...