Post by thread:(OT) RPM/Speedo using instead analog F/V convertor

FWIW, I've found it easier to make a speedo/RPM meter using National Semiconductor's LM2907/LM2917 Frequency to Voltage converter. You can hook up a magnetic pickup directly to the input of the IC (differential input) or using conditioning circuits, the negative lead of the coil. The output is then a voltage that is linearly proportional to the input frequency. Hook this to the LM3914 10 LED bargraph IC and you are done, or use scaling resistors and a cheap 3-1/2 digit panel DMM for digital output. Don't have to worry about refresh rates, timebases, etc, and easily calibrated. Dave

At 08:45 1998-10-23 -0700, you wrote: >FWIW, I've found it easier to make a speedo/RPM meter using >National Semiconductor's LM2907/LM2917 Frequency to Voltage converter. > >You can hook up a magnetic pickup directly to the input of the IC >(differential >input) or using conditioning circuits, the negative lead of the coil. > >The output is then a voltage that is linearly proportional to the input >frequency. If that cirquit use a capacitor for conversion, beware to select one thet has little temp drift (som cap drifts are huge!) /Morgan / Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, SWEDEN \ \ spam_OUTmrtTakeThisOuTiname.com ph +46(0)414 70741 fax +46(0)414 70331 /