BLOOD PRESSURE MONITOR

Yes but i need to design an amplifier that is capable of measuring small oscilations and feed it to ADC but problem is that in PAKISTAN there is no MPX2050,OPA2277 or AD620 aso i have to design whole thing my self i came to ckt that is in my sensor's datasheet(SCX15DN)that gives pressure reading to ADC0831 nw i have to amplify the signal and again ,couple it and feed to another adc.As it hav DC level of 2.5v we chk when it exceeds 4V.Nw how dose freq is related to samples ??(Sory if this is a silly Q)

afnan,
first try to understand the signal conditioning circuit:
the first op-amp is the amplifier which amplifies the output from the pressure transducer to the required voltage level and is fed to one adc channel.
the other two stages using opa2277 are actually band pass filters tend to eliminate the dc component from the signal along with any additional noise from the sensor. In the last stage, a fixed known D.C. component of +2.5V is added so that the oscillations occur in a non-zero environment.
Now, what u have to do is to first practically rig up the analog circuit along with the pressure sensor and practically check if u are getting the required A.C.and D.C. outputs. I would suggest u start with the interfacing once that is confirmed.

As for ur second query , yes, the sampling frequency should be always very high compared to the A.C. wave frequency.
:-)

thank u sir.
mr arun told to
use fig B.But i am using ADC0831 so is it better to use schematic in fig D or Fig B for Bp calculations and sensor i have got is SCX15DN and all circuits are for SCX05Dn and SCX01Dn.Here it makes a confusion that variation of the sensor is from 0 to 60 mv (SCX15Dn) which accordingly assigns 12mv to each 1 Psi.and 0 to 18 mV in case if SCX01DN.
these ckts are fine if i use SCX05Dn.Well Question is that ckt given is for
SCX05Dn but i am using SCX15DN which allows me to have 6mV/Psi and it is only available.For medical use 300mmHg is ab 5.8 Psi.nw for fig B given CKT comes to Voltage 3.5 when sensor voltage reaches 60mV(max pressure).in my case when 300mmHg is achived ckt should be at 3.5V when voltage of sensor reaches to 34.8mV.

By the Formulla
15Psi=90mv
1Psi=6mv
5.8Psi=34.8mv

what modifications are required to change the ckt in Fig D or in
Fig B if i am using SCX 15Dn.and how can i calculate overall gain
of ckts in fig b and D

Afnan plz quit one of the two threads you are running for the same topic.
Abandon this thread and continue the discussion in the other one.

Sure ill soon quit other fourm nd ill continue this 1.

can any 1 tell me dat is it necessary to use op2277 in above fig.Can i use Lt1014 i use op2277
what i want to do is dat measure small ossiliations

Ok please reply.
What makes precsion op amps different 4rm each other.Lt 1014 and opa 2277.

and if i use band pass filter would ir mater if i use band pass filter

well filters are for a purpose, usually designed keeping the next stage in mind.

regarding replacement of LT1014, I would recommend you to download datasheet of both Opamps and review the electrical and operational characteristics. or just see the features of LT1014 and find an identical one from national semiconductor's website.

The LT1014 is a bipolar input opamp whereas the opa is a jfet.
See if you can find LT1055 or LT1022.
As a last option you may try using LF353.

ok ill track them.as there are filters and gain would it b same for them too or i got to disign whole filters again.

what bipolar and jfet op amp differ in ?