Works very well on my LG Nexus 5. Free no ads - can do Paypal donation to dev if you want.
Place phone on the platter with app running and it provides a real-time readout of the RPM when the tt is spinning. (Readout stays readable despite rotation.) More accurate than the strobe disc on my Lenco.
Quartz locked TT's won't need this of course.
https://play.google.com/store/apps/details?id=com.apkossa.rpmeter
I place a cup over the spindle with phone on top to centre the phone for easier reading but it's not required.
Place phone on the platter with app running and it provides a real-time readout of the RPM when the tt is spinning. (Readout stays readable despite rotation.) More accurate than the strobe disc on my Lenco.
Quartz locked TT's won't need this of course.
https://play.google.com/store/apps/details?id=com.apkossa.rpmeter
I place a cup over the spindle with phone on top to centre the phone for easier reading but it's not required.