digital VU meter - 2
digital VU meter - 2
After last part detailed description of thedesign and facilities ofthe accurate, multifaceted digital vu meter,this part’s final instalment deals with the construction and operation of the instrument.
A sdiscussed inPart 1, the circuit consistsof five functional blocks,which are readily recognized in thecomponents layout of the doublesidedthrough-plated printed-circuitboard in Figure 3. The board isavailable ready made—see theReaders services list elsewhere inthis issue. The board should be cutalong the indicated lines into fivediscrete parts, so that each functionalblock gets its own board.This arrangement makes theconstruction very flexible: not onlycan a variety of enclosures be usedto house the meter, but matchingthe function to a specific applicationbecomes straightforward.Figure 3 forms an excellentguide for populating the fiveboards. That of the supply board isstraightforward, although it shouldbe noted that the voltage regulatorneeds cooling. The simplest way ofachieving this is to screw the deviceto the rear panel of the enclosure ifthis is a metal one; if a plastic caseis used, the regulator should be fittedto a heat sink.The S/PDIF interface is providedwith a coaxial connector, K4, towhich the serial data is applied viaa coaxial cable. It is advisable to usegold-plated connectors to ensuregood contact at all times. Fit the devicein a suitable socket to minimizethe risk of damage through soldering.Mount all resistors upright. Thepresent design does not include anoptical input, but it may be seenfrom Figure 4 that a relevant interfacecan be added without any difficulties.An added benefit of such anaddition is that an extra coaxial outputis provided as well.