Uploaded September 2023 | Updated September 2026, 1 day ago
Third part, about a third principle method of measuring capacity …
↓↓↓ Complete description, time index and links below ↓↓↓
In the second video we’ve covered two principle ways of measuring capacity (link below). Turns out that the second principle we’ve had a look at (RC charge curve) lends itself to a third method: RC oscillators. So let’s have a look at those.
We start out with a simple RC oscillator around an inverter with a Schmitt-trigger input and the easy math governing it. But soon we’ll discover that when working with pF and MOhm things are complicated and parasitic effects get very visible.
00:00 Intro – a third way to measure capacity
01:01 RC oscillator – with 74HCT14 Schmitt-trigger inverter
07:08 The math – frequency inverse proportional to capacity
10:34 Duty cycle – not that it matters, but why isn’t it 50%
14:04 Parasitic capacitances – messing up the nice math
24:21 Alternative chips – LMC555 (CMOS) and comparators
26:09 Frequency & EMI – keeping it low is key
27:52 Wrap-up – next time we’ll actually use an MCU, bye
Tutorials youtube.com/playlist?list=PLwq-2MnM58FKn3920rc1V0qoTsQDheTIw
Capacitive Liquid Level Sensing (1): Sensor Basics youtu.be/Jjcym2g2ruk
Capacitive Liquid Level Sensing (2): Measuring Capacity (1) youtu.be/h6ErXsIQWDU
Capacitive Liquid Level Sensing (4): Analog to Digital (1) youtu.be/6-uRvu_0WW8
Capacitive Liquid Level Sensing (5): Analog to Digital (2) youtu.be/BoutyoQyOQI
Capacitive Liquid Level Sensing (6): Analog to Digital (3) youtu.be/g8fjN2WKGN4
Capacitive Liquid Level Sensing (7): Reference Sensor (1) youtu.be/XDtQKoT6Zyo
Capacitive Liquid Level Sensing (8): Reference Sensor (2) youtu.be/pKZHFjDShpM
Capacitive Liquid Level Sensing (9): Dielectric Constant Not Always Matters youtu.be/iQqXeQJgLbc
Capacitive Liquid Level Sensing (10): Errata, Miscellaneous, The End youtu.be/TdAnryA6h-M
#liquid #sensor #capacitance #capacity #capacitor #tutorials #tutorial #how-to #robertssmorgasbord
Third part, about a third principle method of measuring capacity …
↓↓↓ Complete description, time index and links below ↓↓↓
In the second video we’ve covered two principle ways of measuring capacity (link below). Turns out that the second principle we’ve had a look at (RC charge curve) lends itself to a third method: RC oscillators. So let’s have a look at those.
We start out with a simple RC oscillator around an inverter with a Schmitt-trigger input and the easy math governing it. But soon we’ll discover that when working with pF and MOhm things are complicated and parasitic effects get very visible.
00:00 Intro – a third way to measure capacity
01:01 RC oscillator – with 74HCT14 Schmitt-trigger inverter
07:08 The math – frequency inverse proportional to capacity
10:34 Duty cycle – not that it matters, but why isn’t it 50%
14:04 Parasitic capacitances – messing up the nice math
24:21 Alternative chips – LMC555 (CMOS) and comparators
26:09 Frequency & EMI – keeping it low is key
27:52 Wrap-up – next time we’ll actually use an MCU, bye
Tutorials youtube.com/playlist?list=PLwq-2MnM58FKn3920rc1V0qoTsQDheTIw
Capacitive Liquid Level Sensing (1): Sensor Basics youtu.be/Jjcym2g2ruk
Capacitive Liquid Level Sensing (2): Measuring Capacity (1) youtu.be/h6ErXsIQWDU
Capacitive Liquid Level Sensing (4): Analog to Digital (1) youtu.be/6-uRvu_0WW8
Capacitive Liquid Level Sensing (5): Analog to Digital (2) youtu.be/BoutyoQyOQI
Capacitive Liquid Level Sensing (6): Analog to Digital (3) youtu.be/g8fjN2WKGN4
Capacitive Liquid Level Sensing (7): Reference Sensor (1) youtu.be/XDtQKoT6Zyo
Capacitive Liquid Level Sensing (8): Reference Sensor (2) youtu.be/pKZHFjDShpM
Capacitive Liquid Level Sensing (9): Dielectric Constant Not Always Matters youtu.be/iQqXeQJgLbc
Capacitive Liquid Level Sensing (10): Errata, Miscellaneous, The End youtu.be/TdAnryA6h-M
#liquid #sensor #capacitance #capacity #capacitor #tutorials #tutorial #how-to #robertssmorgasbord
