Strobe tachometer (RPM meter) vs True Note

STROBE TACHOMETER When the flicker frequency of light coincides with the speed of any object, such as a fan, the rotating fan may appear to be stationary. Changing the frequency of the flicker of light may help detect the rotation speed. You may easily use the flicker frequency control buttons to quickly assign the flicker frequency with an accuracy of 0.0001 Hz (0.01 RPM): • Up to 1000 Hz (60 000 RPM) for a connected flashlight (see the video on YouTube: https://youtu.be/iq6Xiums05o). • Up to 100 Hz (6000 RPM) for the iPhone flashlight. IF THE SPEED IS MORE THAN UPPER LIMIT, YOU MAY STILL DETERMINE THE SPEED BY FIRST MAKING MEASUREMENTS WITH A LOWER FLICKER FREQUENCY AND THEN MAKING A SIMPLE CALCULATION (AS EXPLAINED IN THE APPENDIX). To change the frequency, you should simply press and hold the button. In the app settings, you can adjust the speed at which the flash rate changes when you press and hold the button. The flicker frequency can be displayed either in Hz or RPM. The image you see will be sharper in lower external light. After a long period of usage, in case of overheating, the iPhone flashlight turns off automatically. LASER TACHOMETER • Measurement range from 0.3 Hz (18 RPM) to 1000 Hz (60 000 RPM). • Step 0.01-0.0001 Hz (1-0.01 RPM). • Update time 1 sec. • 5 mW laser power required. MAGNETIC TACHOMETER This tachometer operates by measuring the magnetic field from a spinning magnet. The magnetic field is measured by the iPhone's magnetometer. The magnetic tachometer is best suited for measuring low rotation speeds (from 6 revolutions per minute). It can also be used for measuring medium rotation speeds (up to 2,700 RPM), but at such speeds there is a risk of spontaneous tearing away of the magnet and strong vibration due to center-of-gravity shift. • Measurement range from 0.1 Hz (6 RPM) to 45 Hz (2,700 RPM). • Step 0.2-2 %. • Update time 2-5 sec.

Use True Note to test a record player to see if it's playing at the correct speed. Here's how: 1. Download the True Note app and open it 2. Print and cut out the included turntable strobe disc 3. Place the strobe disc on your record player and start it at the 33 1/3 RPM speed 4. Tap "START" in the True Note app and shine the flashing LED light from your iOS device onto the strobe disc If your record player is playing at the correct speed, you should be able to make out the individual lines on the strobe disc - and they should appear to remain in the same position (not drifting in one direction). Many record players have an adjustable speed and can be calibrated with the help of True Note. Perhaps you're shopping for a used record player? The True Note strobe disc is small enough that you can fold it in half to keep in your wallet or iPhone case - ready to use when you're at a thrift store or garage sale and want to make sure the turntable you're considering buying works properly.