i would like to have a simple, good enough, easy to use, rpm meter.
i found the dt2234+ on banggood
it is a bit cheap ($12)
but it seems to do the job.
my typical usecase is that i have a spinning motor running at constant speed (hopefully)(typically turnigy), that i may control with odrive (and then i just want a quick and dirty way to check that it spins as i beleive it does). sometimes it’s with another controller (and here i dont have a clue). and sometimes it’s not even a brushless motor.
ideally i woudlnt connect anything mecanically. dont have to use/configure an oscilloscope.
i just want a second pair of eyes
what would you buy/make? how do u do this?