标签: 数显频率计

Twolow-costintegratedcircuitscanbecombinedtocreateasimpledigitalfrequencymeter.Thecombinationofafrequency-to-voltageconverter(FVC)andadual-slope,analog-to-digitaldisplayconverter(ADC)makesasmall2-chipfrequencymeterthatcanberunfromone9-voltbattery.TheADC(TC7136)generatesthevoltagerequiredbytheFVC(TC9400)withinternalregulators.TheTESToutputoftheTC7136isregulatedto5voltsbelowthepositivebatteryterminal(V+)andtheANALOGCOMMONoutputisregulatedto3VbelowV+.TheTC7136isdesignedtodirectlydrivea3-1/2digit,non-multiplexedLCDdisplaysonodigitalconversionisrequired.ThetestvoltageisusedasthereferencesupplyfortheTC9400andANALOGCOMMONservesasthe"ground"forthecomparatorandtheintegratingamplifier.AN37TC7136/TC9400……

用89c51做频率计……