Instrumentation amplifier
Instrumentation amplifier
(OP)
Hi can anyone help me with the design of an instrumentation amplifier.
it is needed to amplify a signal comming from a Hall Effect sensor, I need tips on isolation and circuit design.
it is needed to amplify a signal comming from a Hall Effect sensor, I need tips on isolation and circuit design.





RE: Instrumentation amplifier
One basic feature of the instrumenation amplifier is to provide extremely high input impedance, symmetrical on both inputs. To my mind a Hall Effect Sensor is a device having quite a low output impedance. So an instrumenation amplifier is not necessary. A operational amplifier connected as differential amplifier should be sufficient.
For further information on analog circuits look at the application notes from Analog Devices (http://www.analog.com)
RE: Instrumentation amplifier
http://www.fwbell.com/hallcatalog.pdf
http://www.ti.com/sc/docs/products/msp/control/hmc/thmc45.pdf
etc. for more info
RE: Instrumentation amplifier
I just was reading in my recent issues of EDN magazine a design similiar to this. It utilized two opamps configured from what I can recall as non-inverting configurations with the sensor placed between the non-inverting terminals. The magazine is online and the article can be seen here: http://www.e-insite.net/ednmag/index.asp?layout=article&articleId=CA200383&pubdate=03/21/2002. Hope this is of help?
Cy Drollinger
RE: Instrumentation amplifier
Analog: send spec's
<nbucska@pcperipherals.com>
RE: Instrumentation amplifier
RE: Instrumentation amplifier
RE: Instrumentation amplifier
Why do you need isolation? I guess I have not heard of a hall effect application that required isolation (I have only used for current measurement).
RE: Instrumentation amplifier
Buzzp Well I think i made myself unclear what i was trying to do.
I am using the hall effect sensor to measure current in a conductor by using a splittable ferrite core that will clamp around the wire. the sensor will be mounted in the air gap and the signal needs to be amplified.
I needed some advise on the circuit design of the amplifier circuit and what considerations should be taken into account, what about noise in the cable will the amplifier have sufficient CMRR to cancel the noise etc.
RE: Instrumentation amplifier
RE: Instrumentation amplifier
RE: Instrumentation amplifier
Do not use to long of cable if you are indeed using cable to the hall effect and toroid. It may be better to mount the electronics around the toroid on a PCB, unless the current measurement requires a large toroid (gapped). Good luck.
RE: Instrumentation amplifier
and from the results be able to accurately or within reason tell how much current is flowing in the wire.
I wonder if you know what is the best Hall sensor to do this job. does it have to be a linear Hall sensor, or would any do. I ask this because i have seen many different types some are three legged devices and others are four legged ones. if you can help it would be appreciated.
regards
RE: Instrumentation amplifier
I have the information but it is out in my office.I am in the house right now and being lazy. Next time I am out there I will get some part numbers.
RE: Instrumentation amplifier
RE: Instrumentation amplifier
For xtal mike you don't want instr.amp -- you want a non-inverting, low noise, high gain stage.
<nbucska@pcperipherals.com>
RE: Instrumentation amplifier