The goal of this project is to make an device that measure RPM, Wow, Flutter, Rumble and help Level a turntable.
Right now I am using a AdaFruit Feather board's build in adc and a mems device.
- Adafruit Feather RP2040 Adalogger
- Adafruit FeatherWing OLED - 128x64 OLED
- Adafruit LSM6DS3TR-C 6-DoF Accel + Gyro IMU (for RPM, leveling, and rumble)
- Battery (Size of batter is up to you this is the one I used)
- Adafruit MAX17048 (Optional used for monitoring battery status)
- Power Switch (Optional)
- STEMMA QT 4pin cable (Number depends on how you build the circuit)
- JST-PH 2-pin Jumper Cable (Depends which power status circuit you use)
- DC Offset Circut for ADC
- 2 RCA connectors
- 2 Resistors of the same value (10kohm)
- 1 Capacitor (10uF)
- 1 Diode (1N4148)
- Some wire
Most of the wiring is done with STEMMA QT except for the power switch.
- A: Move selection up
- B: Select
- C: Move selection down
This mode will show a real time rpm value. If you start the measurement it will find the avg, min, max rpms, and wow and flutter.
- A: Back to main menu
- B: Start measuring RPM data
This mode helps you level your turntable.
- A: Back to main menu
This mode will let you measure the rumble of your turntable in dB.
- A: Back to main menu
- B: Start measuring rumble data
This mode will try and reduce noise from the sensor.
- A: Back to main menu
- B: Starts calibration
This works by getting the output from a test record from your turntable pre-amp and running through the RP2040's ADC. The signal will need a DC offset for the ADC to work correctly, so I made this simple circuit below.
This will give the input signal VCC/2 offset, this is done with the resistors in a voltage divider configuration. The capacitor is for DC decoupling the input, and the diode is used to clamp the signal above 0V.
- A: Back to main menu
- B: Freeze the measurements
- C: Clears the crosstalk moving avg.
- A: Back to main menu
More to come soon.
