Quote:
Originally posted by CHSguard72
I went to Radio Shack, and bought 90% of the stuff on the schematics. I bought a simple Op-Amp ($.99), but on the back of the box schematics, it only has 2 inputs, and an output. Your schematics have a ground coming out, as well as another wire (#4 on sheet) that appears to be +12v. I guess I'll have to take another trip out to R.S. and pick one up that looks similar.
Also, it dawned on me just now that i will have to put many resisters in series to create a net resistance of 12.1kOhm's and 2.2kOhms. I did not see these resisters at R.S, so i didnt buy them, only the nice round 10X mulitples R.S. had. Looks like 1 more trip out to Radio Shack today........ but probably not the last.....
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Well, the resistor values used can be changed....all you end up with is a different range of output. (I chose the values to optimize the output for both 30A and 20A breakers)
If you went with 10K and 100K, you would have a gain of 10 vs 8.26 which will give you a lower full scale MAX current measuring ability. This is actually BETTER for the 40A breaker since it will have a lower resistance.
But I can't over-state the importance of the OP-AMP. Something like a 741 or a 324 will just NOT do the job at all. (If I remember, the 324 is good at sensing close to the lower supply, not the upper supply)
BTW: The 6134 is pin compatible with the LM324, so if you built it for the 324, (in a socket) you can simply switch in the 6134 when they come in.
-Quentin