Digital VU meter (part 1):

Most of us have over the years become familiar with the nervously moving pointers or LED bars of the vu (visual unit) meter on the front panel of a cassette tape recorder or mixing panel that indicate the level of the a.f. signal. The circuit presented in this twopart article is a variant of this meter that can be inserted directly in series with the a.f. signal line. Its specifications are reminiscent of professional equipment. We are not entirely certain, but think that this is the first DIY vu meter ever published in a magazine.