Low cost, small size DIP Instrumentation amplifier IC

[chetanthegreat]

Hello folks,
I am facing a bit of trouble regarding the signal
conditioning part. The standard 3 Opamp instrumentation amplifier
using TL084 I am planning to inculcate becomes very bulky considering
all the resisters involved for gain adjustment and similar tasks.
There are 6 of these circuits on the entire board, thus resulting in
unusually large PCB for the project.
I am satisfied with the performance of the above
circuit but I have to find a way to reduce the size of PCB somehow. As
of now I have shortlisted AD620/622 and some similar products from AD
as alternatives but they are pretty expensive (at least compared to
good ol TL084s )
Any suggestions?

Regards.

Chetan.

 

[DJ Delorie]

I am satisfied with the performance of the above
circuit but I have to find a way to reduce the size of PCB somehow.

Have you considered switching to SMT packages? Compare 20x9mm for
DIP-14 vs 9x6mm for TSSOP. Also, SMT resistors take up much less
space than through-hole.

For an example of how small SMT can get, see
http://www.delorie.com/pcb/smd-challenge/

 

[chetanthegreat]

I am afraid this is gonna be a very early version of the prototype,
and all the other components are THT compatibles.
For the end product SMT is the best solution, I agree. But for
developement, nothing beats convenience of THT boards.

So it's like some 6 14PDIPs and resistors on one hand and just the 6
8PDIPs on the other(If i find something similar to AD62X but cost
effective.)

 

[John Popelish]

I am afraid this is gonna be a very early version of the prototype,
and all the other components are THT compatibles.
For the end product SMT is the best solution, I agree. But for
developement, nothing beats convenience of THT boards.

So it's like some 6 14PDIPs and resistors on one hand and just the 6
8PDIPs on the other(If i find something similar to AD62X but cost
effective.)

Have you looked into the two opamp version of the I.A.?
That would allow you to make two per quad opamp pack.

 

[chetanthegreat]

Well ... I can very well make my peace with all these things, but not
in the budget I have assigned for it.
The 3 opamp design (2 unity gain buffers and a difference amp ) using
TL084 costs around half a dollar at the most but if i am to go ahead
with Monolithic Instrumentation amplifier , the minimum starts from $
1 -2 a piece, that too if you buy it in bulk.

So basically I am searching for a instrumentation amplifier pref 8
PDIP , which is inexpensive.

regards.

 

[John Fields]

Well ... I can very well make my peace with all these things, but not
in the budget I have assigned for it.
The 3 opamp design (2 unity gain buffers and a difference amp ) using
TL084 costs around half a dollar at the most but if i am to go ahead
with Monolithic Instrumentation amplifier , the minimum starts from $
1 -2 a piece, that too if you buy it in bulk.

So basically I am searching for a instrumentation amplifier pref 8
PDIP , which is inexpensive.

 

[chetanthegreat]

will check them out for sure !

Thank you.

 

[Rich Grise]

I am afraid this is gonna be a very early version of the prototype,
and all the other components are THT compatibles.
For the end product SMT is the best solution, I agree. But for
developement, nothing beats convenience of THT boards.

So it's like some 6 14PDIPs and resistors on one hand and just the 6
8PDIPs on the other(If i find something similar to AD62X but cost
effective.)

You can mount TH resistors, diodes, well, any axial part vertically, on
0.1" centers. Just bend the one lead over, and optionally cover it with
teflon tubing.

Good Luck!
Rich

 

[chetanthegreat]

@ Rich

Thats a pretty good trick. Wonder how didn't I recall that ?

I ll think about it.
Thanks.