Hi, I'm using a sensor connected to a amplifier of gain 100... But the output gives me only about 20-50mV Vpeak... How can i make the output to have at least 1V Vpeak?
Hi, I'm using a sensor connected to a amplifier of gain 100... But the output gives me only about 20-50mV Vpeak... How can i make the output to have at least 1V Vpeak?
Hi, I'm using a sensor connected to a amplifier of gain 100... But the output gives me only about 20-50mV Vpeak... How can i make the output to have at least 1V Vpeak?
hi,
As Len says, use a 50R gain pot, this will give an overall gain of 1000.
If you got 50mV peak at *100, you should get 500mV at *1000.
What are you going to do with the 500mV signal?
If you must have a 1Vpk signal, then add another non inverting OPA to the output, a gain of *2 should give you 1Vpk.
Or use a 25R gain pot setting for a gain of 2000. Check the datasheet for the Vout limits at a gain of 2000!!
What sensor bridge excitation voltage are you using?
hi,
As the datasheet explains, the device is ratiometric and the mV output sensitivity is proportional to the supply voltage.
Using a low 3V supply, will give a low sensitivity. Is it possible that you can use say,+5V to the sensor and OPA in order to increase the sensitivity?
Hi, I'm using a sensor connected to a amplifier of gain 100... But the output gives me only about 20-50mV Vpeak... How can i make the output to have at least 1V Vpeak?
hi,
Looking thru the datasheet for the sensor states minimum mV/V is 7.5mV/Oersted and maximum mV/V is 13mV/Oe.
So with your original Vsupply of 3V, you should get an output from the sensor of min=22.5mV and max= 39mV [for 1 Oe]
As your original Gain was 100, this should give an output from the OPA of 2.25V or 3.9V???? [for 1 Oe]
The linear range of the sensor is 0.6 to 3 Oe.
Your value of 20mV thru 50mVout would suggest that there is something wrong with the circuit, do you have a diagram?
and which magnetic field are you measuring?
As this is a school project and the design of the circuit is not done by me (done by previous student) i do not have the circuit diagram. I was given the circuit.
I'm using the sensor together with a magnet to detect heart rate.
But when i use the sensor to detect magnetic field from a permerant magnet, the output is about 1+V to 2+V. It seems that detecting heart rate using the sensor would result in very weak output.
As this is a school project and the design of the circuit is not done by me (done by previous student) i do not have the circuit diagram. I was given the circuit.
I'm using the sensor together with a magnet to detect heart rate.
But when i use the sensor to detect magnetic field from a permerant magnet, the output is about 1+V to 2+V. It seems that detecting heart rate using the sensor would result in very weak output.
hi,
The datasheet states that the linear region for the sensor is 0.6 thru 3.0 Oe, so I would imagine the magnetic field from the heart muscle would fall well below this Oe level.
I would expect stray electromagnetic fields from nearby equipment to be a cause of detection problems in the system
You would just get a very weak signal, try to amplify by 2000.
What is the OPA output connected to?, why must it be 1Vpk?
I see... ok... I'll try 2000 gain... The OPA is connected to a µC. From the µC datasheet, the min input voltage to the port should be 0.9V and max should be 2.1V.
I see... ok... I'll try 2000 gain... The OPA is connected to a µC. From the µC datasheet, the min input voltage to the port should be 0.9V and max should be 2.1V.
You can use the 'Ref' pin on the OPA to give a positive offset to the output signal, say by 0.5V.
So the 'ac' output signal of 2Vppk, would appear to the mcu input as +0.5V to 2.5V