Failed Fab ECG 50Hz
Currently under debugging
Currently under debugging
According to wikipedia:
The utility frequency, (power) line frequency (American English) or mains
frequency (British English) is the frequency of the oscillations of alternating
current (AC) in an electric power grid transmitted from a power plant to
the end-user.
In large parts of the world this is 50 Hz, although in the Americas and
parts of Asia it is typically 60 Hz.
Current usage by country or region is given in the list of mains
power around the world. During the development of commercial electric power
systems in the late 19th and early 20th centuries, many different frequencies
(and voltages) had been used. Large investment in equipment at one frequency
made standardization a slow process. However, as of the turn of the 21st
century, places that now use the 50 Hz frequency tend to use 220–240 V,
and those that now use 60 Hz tend to use 100–127 V. Both frequencies coexist
today (Japan uses both) with no great technical reason to prefer one over
the other.
Some parts of the FabECG are designed for US power supply settings. It's needed to adapt to the countre of use. In my case, I live in Europe, so the final Low Pass Filter should be for 50Hz.
There are three passive LPF RC configuration.
R=25k, C=220nF
Transfer funtion:
G(s)=(181.818181/(s+181.818181))
Cut-off frequency:
fc=28.937262Hz
Pole:
p=-28.937262[Hz]
Images from okawa_deshi.jp
There are three passive LPF RC configuration.
R=30k, C=220nF
Transfer funtion:
G(s)=(151.515151/(s+151.515151))
Cut-off frequency:
fc=24.1142385Hz
Pole:
p=-24.1142385[Hz]
Images from okawa_deshi.jp
Configuration:
R1, R2=30k,
C1, C2=220nF
Transfer funtion:
G(s)=(22956.8411387/(s2+303.0303030s+22956.8411387))
Cut-off frequency:
fc=24.114385317Hz
Poles:
p=-24.114385317 +7.32237219398E-9i[Hz]
|p|= 24.114385317[Hz]
p = -24.114385317-3.67393128599E-8i[Hz] |p|= 24.114385317[Hz]
Images from okawa_deshi.jp
For this try, I will make an ACTIVE SALLEN-KEY LPF
In order to avoid any problem and get the best ECG signal, I will repeat the ECG cables with better quality cables.
This is the new schematic of Fab ECG with the 50Hz active LPF
And, after moving a little bit all components in order to make it smaller, this is the new board:
Download Eagle docs here
Download Component list
Download traces to mill
Download exterior to cut
These files are the last version after debugging (see next section)
Milling with Modela
This is the Fab ECG 50Hz after milling and soldering
but... it doesn't work!!!
So, let's debug step by step.
oh, no... I realize that there are some wires that are not milled. There
were on schematic but they disapear on the board. It seems that some components
weren't linked with wire.
I'm going to try to solve that problem with some 3D wire. lol!
I'm going to try to solve that problem with some 3D wire. lol!
But, after some tries, still doesn't work.
I think, the best option now is start from zero. Debug the schematic,
board, mill again, and so on.
