From: Moritz von Buttlar (info_at_baltic-microsolutions.de)
Date: 2001-12-20 11:24:21
Hi !
>Here, as it does not make difference if the cost is $15 or $20
>more, really, one could surely throw in 4 separate converters,
>and make the small risc actually do something for the money spent
>on it.
I also had this idea :) Already ordered some samples some time ago for
this purpose.
Nice to hear that the FTDI parts and drivers are easy to use in
>practice as well. Only used Uarts, SPI, I2C, CAN and DSP sync
>serial in the past, yet not fearing USB too much, as it
>can not be a quantum leap in complexity compared to CAN imho.
I'm planing to use a device called a LabJack for my instrument. It's a complete
USB measuring device with lots of features (including LabView Driver) for only
99$. So I haven't used the FTDI parts myself. Just read about them.
>Q1: Why not just cut the working amp from the earlier "monolithium"
>( rs232eeg) as one gets the impression it actually worked with
>fairly little trouble ?
First, it's not safe if the INA114 has some internal malfunction. Second,
it doesn't have all those
nice right-leg drivers, shield drivers and so on. Also there's maybe some
aliasing.
>Q2: are the blue outlines over the original rs232eeg board
>for copper-box-shielding the amp-sections from 60 Hz, similar
>to many commercial PC A/D cards that otherwise would suffer
>from too much noise ... ?
No. When I saw Joergs prototype it was just an ordinary PCB. I think the blue
stuff is some kind of grounding area. (Never understood how to generate it
with eagle).
>Q3: Is there any realistic way to get low-noise enough design without
>the copper/nickel plated shieldboxes ?
Maybe we should try with.
>Q4: Why is the right-leg grounding best, instead, of, say, left-
>ear grounding, or middle-finger grounding ?
I think it's called like this for historical reasons.
>Q5: Could you please let me know what is your favorite book or
>resource for learning analog shielding/grounding/guarding techniques
>and their optimal PCB layout techniques, so I could attempt some
>alternativewhat-if trials, even if they are worthless, but just would
>like to learn to come up with decent low-noise, nano-microvolt range
>amps, as there are those UV-photodiode applications also, where one
>could benefit from learning the low noise techniques.
I copied some nice low noise book some time ago, but I don't have it with
me at the moment.
Maybe I can send you the name next week. I don't know much about this topic.
Moritz
---------------------------------------------------
Moritz von Buttlar
Flash uC/DSP Development http://www.baltic-microsolutions.de
Free EEG Design http://openeeg.sf.net
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