From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2002-03-07 16:53:43
Dear Andreas:
I have a Philips CD-RW recorder with optical inputs. Could that could be used for testing?
And yes I would like your help on the PCB-layouts.
A quick story to make you giggle. Around 1971 I was working as a consultant for a company doing Military contract work. I designed the digital frontend for a phase locked loop 1 gigahertz oscillator. This involved doing microstrip PC board layouts for the gigahertz ECL logic prescaler divider circuit. I made the prototype using a Dremil tool and a 5 mil thick cutting wheel and a razor blade.
Do I want to do that again? NO!
Juergen P. (Jim) Meissner
Check out my Website at www.MeissnerResearch.com
Read about the benefits of the Brain State Synchronizer sounds for improving your life and health.
----- Original Message -----
From: sleeper75se
To: buildcheapeeg_at_yahoogroups.com
Sent: Thursday, March 07, 2002 2:16 AM
Subject: [buildcheapeeg] Re: High resolution EEG schematic
--- In buildcheapeeg_at_yahoogroups.com, "Jim Meissner" <jpmeissner_at_mindspring.com> wrote:
> Dear Andreas:
>
> This looks terrific! I would like to try to build it.
Hi Jim,
great! I think this could be something viable...
> Could you give me some help in locating the parts?
No problems, I have a bunch of links for you below.
> Will you be able to help with the software?
Absolutely. For initial testing, you don't even need custom software,
a regular sound editor is sufficient, but later on, we can design a
few classes that plug into the biofeedback app.
On to some practicalities:
I can probably create PCB-layouts faster than you, since I already
have everything set up. Or are you interested in doing it yourself?
All of the passives, the opamps and oscillator are available through
digikey (I'll create a BOM with part numbers).
To find the audio-circuits, contacting the manufacturer or an
authorized dealer is easiest. I can imagine the parts are popular
with hobbyists so there are certainly a number of small outlets, but
I can't help you find those, since I'm outside the US.
Toshiba, Toslink (TOTX173) module:
Distributors: http://www.toshiba.com/taec/howtobuy/
Datasheet (broken file?): http://www.toshiba.com/taec/cgi-
bin/display.cgi?table=Category&CategoryID=7071
Cirrus logic circuits:
Distributors: http://www.cirrus.com/corporate/contacts/sales.cfm
Datasheets: http://www.cirrus.com Search for CS5360 and CS8405A
CS5360 is available in 20-pin SSOP only. CS5360-KS is the commercial
temperature range type.
CS8405A is available in either 28-pin SOIC (CS8405A-CS) or TSSOP
(CS8405A-CZ). My half-made PCB layout is designed for the SOIC
package - no point in trying to make it difficult.
Reading the specs one would think that they are expensive parts. They
are not. CS5360 + CS8405A costs about $10-$12 total in single
quantities. The toslink module is $6. Too bad this design doesn't
scale well or a larger number of channels would be quite economical.
A neat thing about Cirrus is that they have a free schematic and
layout service. (Not sure if it is free for individuals...) The phone-
number given in the data-sheets is (512) 445-7222
Soundcards - a tricky subject. The CS8405A in the schematic is
currently wired for professional audio and we don't want to risk
having some cheap consumer product with an onboard DSP do highpass
filtering on us, so either professional / semiprofessional board or a
really cheap junk board probably works best.
I did a search and the first company I came across that had
soundcards with toslink-inputs was this
The products are here: http://www.core-sound.com/dio_2448.html ($105)
and here: http://www.core-sound.com/dio_2496.html ($199)
Both boards come with a 30-day trial period so if they don't work you
can send them back, but it's probably best to ask first if they do HP-
filtering and how well they handle professional audio formats.
Finally, the PCB should probably be factory-made. Olimex in Bulgaria
is the cheapest manufacturer I know of, though I have yet to order
from them. Delivery time is about a week for boards with >10 mil
traces and two weeks for boards with <10 mil traces. Cost: estimated
$35-$40 for a single euro-board.
Their website is here: http://www.olimex.com/pcb/index.html
Regards,
Andreas
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This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:39 BST