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10-32 — elektor october 1980 LCD frequency counter Tuning scale with LCD A few years ago, building a digital tuning scale required printed circuit boards riddled with ICs. Modern semi- conductor technology has brought everything down to size — to a single IC in fact. The SDA 5680A recently produced by Siemens includes every- thing needed to replace the mechanical tuning scale of a receiver with a five figure digital readout. By using a liquid crystal display (FAN 5132T) current consumption is reduced to such an extent that it is even possible to build it into a portable receiver. The only snag is that the choice of MW stations is limited. The circuit The complete circuit diagram given in figure 1 shows that apart from the IC and the display, very few components are required. There is no need to worry about the LCD control. The display is connected directly to outputs 12 ... 28 of the counter. For a minimum of connections and a maximum output, three step multiplexing (as descri...