Uploaded December 2025 | Updated September 2026, 2 days ago
Creating an analog filter to extract the motor current’s AC component …
↓↓↓ Complete description, time index and links below ↓↓↓
In the previous video we’ve finished our new low noise, isolated RS-485 transceiver circuitry (link below). It’s time for something new and frankly experimental: Measuring the motor’s RPM by analyzing the sinusoidal fluctuations in its current.
First we have a look at the raw sinusoidal AC component of the motor current. Then we build a bog standard active band pass filter to extract it. We find that filter lacking and build an improved filter circuit with promising results.
00:00 Intro – let’s tackle the RPM measurement
00:45 Current fluctuations – sinusoidal, varying frequency
05:07 Signal processing – high pass, low pass, amplifier
06:55 Active band path filter – theory and calculations
10:43 Circuit 1 – bog standard op amp band pass
16:14 Test 1 – noise problem at lower motor power
19:19 Circuit 2 – high pass, 2nd order low pass, op amp
23:45 Test 2 – works, but still room for improvement
27:19 Wrap-up – next is the analog comparator, bye
Full Fly-by-Wire Electric Outboard youtube.com/playlist?list=PLwq-2MnM58FKvpYgFXgNCjlKo14L0KI16
Full Fly-by-Wire Electric Outboard (24): New Isolated RS-485 Transceiver (2) youtu.be/7B94gJ0ky80
Full Fly-by-Wire Electric Outboard (26): RPM Measurement via Motor Current (2) youtu.be/LOpRj7fxl8E
Haswing Protruar 2.0 24V Trolling Motor – More Reverse Engineering youtu.be/RAsr5ENhv88
N-th Order RC Filters for Analog Voltages from PWM Signals – The Hard Way youtu.be/a5pN_q2-PG
#flybywire #electricoutboard #haswing #trollingmotor #outboardmotor #outboard #robertssmorgasbord
Creating an analog filter to extract the motor current’s AC component …
↓↓↓ Complete description, time index and links below ↓↓↓
In the previous video we’ve finished our new low noise, isolated RS-485 transceiver circuitry (link below). It’s time for something new and frankly experimental: Measuring the motor’s RPM by analyzing the sinusoidal fluctuations in its current.
First we have a look at the raw sinusoidal AC component of the motor current. Then we build a bog standard active band pass filter to extract it. We find that filter lacking and build an improved filter circuit with promising results.
00:00 Intro – let’s tackle the RPM measurement
00:45 Current fluctuations – sinusoidal, varying frequency
05:07 Signal processing – high pass, low pass, amplifier
06:55 Active band path filter – theory and calculations
10:43 Circuit 1 – bog standard op amp band pass
16:14 Test 1 – noise problem at lower motor power
19:19 Circuit 2 – high pass, 2nd order low pass, op amp
23:45 Test 2 – works, but still room for improvement
27:19 Wrap-up – next is the analog comparator, bye
Full Fly-by-Wire Electric Outboard youtube.com/playlist?list=PLwq-2MnM58FKvpYgFXgNCjlKo14L0KI16
Full Fly-by-Wire Electric Outboard (24): New Isolated RS-485 Transceiver (2) youtu.be/7B94gJ0ky80
Full Fly-by-Wire Electric Outboard (26): RPM Measurement via Motor Current (2) youtu.be/LOpRj7fxl8E
Haswing Protruar 2.0 24V Trolling Motor – More Reverse Engineering youtu.be/RAsr5ENhv88
N-th Order RC Filters for Analog Voltages from PWM Signals – The Hard Way youtu.be/a5pN_q2-PG
#flybywire #electricoutboard #haswing #trollingmotor #outboardmotor #outboard #robertssmorgasbord
