From: yaniv_vi_at_yahoo.com
Date: 2000-10-20 23:24:14
--- In buildcheapeeg_at_egroups.com, "Thomas Carr" <tomcarr_at_e...> wrote:
hi to all
> Hi Yaniv, Joerg, Rob and everyone,
>
> I'm just emailing some basic questions I have at this stage, as I
told
> Yaniv, I don't really have time this year to do R&D but am still
interested
> in the project. As I have said, I have a manufacturing facility in
Los
> Angeles which makes industrial computers and can do this if it is
desired.
> My true interest is in the creation of a reasonable EEG, I think
the time
> has come, and will be happy just to see the product available to
all,
> regardless of my involvement in the creation. However, design and
> manufacture of a product like this is something I have experience
at, so
> issues are easy for me to see. At this time, I see these issues
that raise
> questions for me:
>
> 1. Investment by Joerg and Rob
> I commend the efforts and time dedication of Joerg and Rob and look
forward
> to this project having postive results for all concerned. As I
work with
> consultants all the time, it is important for anyone contributing
to a
> project like this to have comfort with the level of integrity of the
> participants, so I would suggest that these issues are important
for anyone
> doing work, it's an investment of your time, so be specific on
these issues
> (ie, value your work), don't wait and expect everything will work
out to
> your satisfaction. Increased communication is the key on this
issue.
>
> 2. Amplifiers
> The amplifiers Joerg is designing don't appear to have any expensive
> components, I have accounts with most major electronics distributor
and so
> can usually obtain parts at a significant savings to radio shack or
even the
> broad based players like digikey. The parts on the amplifiers will
probably
> be matched by the pcb 'real-estate' cost, and the assembly another
equal
> part. I would guesstimate this at about $10+ per amplifier. I
think that
> Joerg is correct in careful consideration of these amplifiers.
Biosystems
> amplifier concepts are much more sophisticated than Brainmaster and
I can
> say that I've worked with sensor interfaces to micro-processors for
about a
> decade, and this is where systems always fail or perform poorly.
It would
> be wise to understand that this part of the platform will require
the most
> testing and fine tuning. If we succeed in a big way here, we will
have an
> excellent product. But tweaking this can take a lot if time.
my view on the product is this - after we would get something to the
market - the market would grow and then big companies would come
with better and cheaper design .so we don't need to waste a lot of
time in making the finest eeg . just something cheap that works good -
not excellent . 2 channels are surely enough for this purpose .
and i don't see any reasons to exceed the brainmaster spec .
why ? doesn't it works good ? don't clinicans buy it ?
why do people need more at this 1st step?
>
> 3. A/d
> Is there a current plan regarding the a/d? biosemi uses a 16 bit,
I'm not
> sure that an 8 bit won't due, has anyone looked into this? as we
are
> measuring brainwaves from 1-40hz, it would seem that 8 bit would
easily give
> us .2 hz resolution, which should be adequate, is my thinking
correct? A 16
> bit bus may increase costs.
>
> 4. channels
> as well, how many input channels are we thinking of? brainmaster
has 2
> channel, but if we create the amplifiers in a modular format, we
could have
> up to 8 channels pretty easily, I don't know the performance value
of this,
> but it would seem that more than 2 channels would increase value and
> application and a basic system could then be increased easily by
adding more
> amplifier modules. Typically, then, within the chassis we might
put 2
> amplifiers on the motherboard and then have headers for adding
amplifier
> modules.
>
> 5.opto-isolation
see the comm section about irda .
> In the biosemi system, they multiplex the A/D through fiber optics
and then
> use a pc card to interface the data, this is of course a very
expensive way
> to go (not in general but within the $ parameters of this
project). A key
> here is the opto-isolation. Bio-system is using fiber optics, when
I asked
> Tom Collura, he suggested a "comercial opto-isolator", does anyone
have any
> imput on this? The idea, as I've dealt with this before but in other
> circumstances, is that we have a small potential on the amplifier
side for
> safety and use the opto-isolators to isolate from the pc side.
>
> 6.comm method
> It appears you are focused more towards rs232 and 485, rather than
a pc card
> like the biosystem uses, in which case we can use the parrallel
port on a pc
> to accept signal data. The maxims 232 (or233) chips are pretty
standard, we
> can reduce to 3 wire interface if we take it down to 485 using a
75176. If
> we use the right micro-processor, we don't have to add a uart,
there are
> uarts on board, so this saves $, too.
about comm method - because we want
1.low cost interface
2.simple cheap testing - but ultimate safety (isolation )
i think it's best to use low speed irda interface .
my price estimation - if you have a micro - you need about $2 more
of components .
of course the user should have irda card installed in the computer .
so maybe it's even better to do just simple infrared interface
card that connects to parallel port - as the next side .
but i really think infrared comm is necessary in this project .
>
> 7. 3 parts to software
> Does Joerg have a micro-processor in mind and is he writing that
software.
> Or is Rob writing the PC software and the micro-processor
software? Then,
> there is the comm software itself, the micro-processor is usually
> self-sufficient and the PC is also, the comm process is the link.
> Which software is Rob using for the PC? I know comm functions on
visual
> Basic are pretty straightforward, but you typically have to drop
the data
> into a database that your user interface then accesses. Visual C++
is
> certainly infinitely more capable, but much more complex to write
as well
> unless you already have some adaptable software. This is
absolutely where
> the most time investment will take place, and I mean A LOT of time.
>
> 8. the pcb
> Does Joerg have CAD capability for schematic capture and PCB
layout, though
> I don't have too much time, this is a very important aspect to a
product's
> longterm reliability and robustness, as well as maintaining cost
> considerations. As stated before, while I don't have the time to
do the R&D
> this year, I can probably do the board layout work for the project
when it
> gets to that stage if no one else has capabilities and experience
(and after
> doing several motherboards, I can say experience is key, probably
why Tom
> Collura used a pre-made board). So, in this way, I can take the
product
> from prototype to successful manufacture. I interject now as this
is a very
> important step, good to have a tentative plan in advance.
>
> 9. major components cost estimate
i don't agree with many of this .
i think first we should design for lowest cost and then see how much
it costs .
joerg did one design - it costs 70$ in parts .
i think you over rated the price of marketing etc .
again i have talked with some cmanufacturer of assemled kits ,
and think if the parts + pcb costs $70
my feeling that all assembly +marketing costs should be $30 per unit
.
many marketin could done freely on the net - using futurehealth.org ,
and other channels .
but again first let's design the lowest cost optimal design.
> we have to have these components which are pricey: micro-processor
($5),
> ram($3), rom ($3), 232 ($4), power supply transformer ($8), opto-
isolation
> (?), a/d($5), pcb ($15), box ($7), LED's and switches ($5),
assembly/tech
> ($30), misc parts ($5-10). If we go with a mpu that has ram and rom
> onboard, we may have to get a uart ($5) so the tradeoffs have to be
> considered. With 2 amplifiers, the cost is up to about $100.
Typically in
> manufacturing, you'd figure at least a 2:1 ratio for other costs
compared to
> COGS, so we're looking at about $300, this all depends on volume,
which
> won't be large as we are starting from scratch with no resources.
So, while
> this is much cheaper than $1000 for the 2 channel brainmaster, it's
not
> $100. Basically, if you remember, Yaniv, this was what I suggested
the sale
> price would be at the start of this project. I welcome correction
in my
> estimate. What is the other $200 for? basically overhead,
marketing,
> distribution and income for those who are investing their valued
time- at
> this point, these are all theoretical. If you go through
distribution, they
> mark up, which is figured as a discount off the list price (list
price is
> $300, they get 40% off = $180 to the wholesaler). Typically, the
> manufacturer makes more than the wholesaler, so this would raise
the sale
> price to $400. Welcome to the world of manufacturing :) As I said,
good to
> look at this ahead of time, I value everyone and feel they deserve
to be
> compensated accordingly. And it's good to take a look at these
issues before
> they become issues :)
>
> even a prototype run of 25 will cost $3-4000 as you have to
purchase parts
> in quantity and there are engineering start up charges, where is
this budget
> coming from, which says nothing about promotional costs which will
be just
> as much just to get started. underestimating it won't change the
bottom
> line.
>
> best regards, tom carr
> tomcarr_at_p...
> www.piercingtheveil.com
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