hum... as you'll see the output signal will be pulsed so should read frequency. But if you want, you can convert it to voltage... for sure. An addition RC circuit + opamp as buffer will do so. Now you need 1 double opamp(747,tlo72,tlo82,Ne5532....) to do the *preamp* + frequency to voltage conversion. or there's a often use frequency to voltage converter on the market called LM2917. see datasheet
http://www.national.com/ds/LM/LM2907.pdf