From: Sajith Goonesekera (sajith_at_magix.com.sg)
Date: 2001-05-28 01:13:05
Hi
> Did you make a pcb ? (If yes, please post the *.sch and *.brd file for
review)
> Or did you use manual wiring ?
I did manual wiring before making the PCB.
> You can make basic tests by using the calibration voltage output pad4 and
pad1.
> However the calibration voltage is produced by the AT90S4433.
> To simulate this signal you only need to connect TTL (0..5V) 10Hz source
> to X1 pin 2.
I have build an Oscillator using NE555 and get 50uV about 10Hz signal.
I got the square wave single.
> Connect ch1+ and ch1- to pad4 and pad1. Do the same with ch2+ and ch2-.
> You should now get a 0.4Vpp rectangle-wave signal (some distorsions due to
> butterworth filter) with a DC component of Vref/2 (2V) at ADIN0 and
ADIN1.
>
> If you get other AC voltages, you should adjust the gain of each channel
with P1 and
> P2.
>
> For further tests see attached *.sch file.
>
> The part designations are according to :
> http://www.biosemi.com/publications/artikel3.htm
I'll try tonight.
> > My ref Voltage is 2.5V is it ok
>
> Were did you measure it and how did you generate it ?
>
> Normally Vref/2 is generated on the digital board and should be 2V.
> Vref is 4 V.
I have divide the 5V into half using two 2.2k and get 2.5V
My Vref/2 is 2.5V
> There have been a few inconsistencies: I have mixed up TLC272 and
> OPA2350.
> TLC272 can be used for all op-amps.
I have used TLC277 instead of TLC272 (I believe it is better than TLC272)
> OPA2350 has lower noise , higher gain*bw and has true rail to rail. But I
suppose
> that it is more expensive and harder to obtain than TLC272. For 10 bit
resolution
> it is not really necessary.
I want to connect it to my brain and measure the singles. How do I do that.
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:30 BST