Motor RPM Meter

An ANEmode DCC Motor Test Rig was modified by adding self adhesive aluminium foil to one half of the circumference of the flywheel on the motor shaft; the other half being coated with matt black paint. A reflective sensor was then aligned with the drum so that as the motor rotated the sensor picked up a square wave signal. The output of the sensor was fed to a PIC microprocessor system to measure and display the speed of rotation. Several DCC decoders were compared. For these tests all the decoders had their CVs set to run at their minimum running speed for speed step 1.  The equivalent mph in the table will of course depend on the gearing of the loco; the values relate to a modern Backmann Steam 4F.
Measurements at Speed Step 1 Decoder                            RPM     Seconds     Equivalent                                                        per rev        miles/hr ESU Lokpilot Micro V4         12           5             0.7 CTelektronik  DCX75D         12           5             0.7 TrainControlSystems M1      26          2.3           1.5 Lokpilot Basic 1.0                49          1.2           2.7 Lenze Gold+ mini                 79         0.8           4.4 Bachmann E-Z RA               161         0.4           9 Bachmann E-Z Command     189         0.3          10.6
RPM Measurement system comprising a ByPic BV504 controller & display being fed a square wave 5v signal from the OPB703 or OPB704 sensor circuit added to the ANEmode DCC Motor Test Rig.
Close up of Optek Sensor and Vero-board circuit.
The software I developed for measuring RPM to run on a ByPic BV504 can be downloaded here    as a PDF  file                        or   as a BAS file . Full details of the ByPic Development System can be found on the ByPic site.
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