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I have a clue: make the gain of the ADC inversely proportional to the amplitude of the signal. That is, a more confident measurement is taken when the interference signal is lowest, and the least confident measurement when the interfering signal is high. Also, add artificial noise when the...
There's an alternative to the accelerometer. One would have a green LED and photoreceptor, that would measure the component of the signal due to outside disturbances, and reject it. What technique could I use to reject this signal/phase?
I want to implement a heart rate monitor for sports activity based on the principle of LED-sensor sensing through soft tissue (example Optical Heart Rate Monitor : Low Cost USB DAQ). However, my experiments show that there's a huge component due to movement of the sensor while exercising, and...
Hi. I want to know of any ICs implementing a photodiode+preamp. The OPT101 is an option (see image), but it doesn't meet some of my requirements, so I need to evaluate alternatives. Thanks.
I'm interested in building an oximeter. I have a question regarding the influence of motion error in the readings. How come that a lot of articles say that medical oximetry is prone to errors by movement, yet use of oximeters in sports is ok? Thanks.
Electrodes for sweat lactate pH measurement
I want to use this circuit for measuring pH of sweat:
Simple pH Meter Circuit Diagram
This would be useful to assess the lactic acid content.
I might as well try zinc-copper. There's also zinc-magnesium. How can I coat a PCB copper trace with zinc...
Hi. I thought about an ADC that would work this way and be very exact for a signal of known phase and frequency:
The signal is clocked in and when the integrator output is at the same level of Vref, a logic level is triggered. The input voltage is then proportional to the time interval. Note...
I don't understand too much about these kind of ground loops. I thought that it was an in-circuit concept.
Is this a solution? I'm not sure I understand it. Does it mean that I can connect the ground clip of my oscilloscope probe to protective ground with a capacitor and a resistor? The circuit...
I just found out that if I connect all three points of the oscilloscope to ground, I get the 60 Hz noise, like shown in the pictures. The scope is at 1 mV/div..
If I turn the supply off so that my circuit runs on the 10000 uF capacitors alone, the 60 Hz noise goes away. Maybe my sensor is picking up the supply magnetic field. But it's 2 meters away.
Can you advice on whether it's better to amplify the signal at the sensor or at the ADC? My shielded...
I see 2 mV noise which seems high frequency, and 2 mV looks like 60 Hz. It looks a lot like the supply noise, but I thought the op amp rejection ratio would take care of that.
L1 and L2 are actually a single inductor coil, whose center is attached to ground. I'm trying to measure an AC magnetic field at 100 KHz (can make some effort to lower that to 40). I don't know what to do with cable A and cable B. I could either measure close to the inductor coil and send the...
I'm making a 16-bit app. I have an AC signal of 100 KHz, 5 mV from a sensor at 1 meter. Noise measured with an oscilloscope is 300 uV. After using INA111 at 1 gain I have 2000 uV noise. My V+ rail (12V) has 4000uV (I guess 500 KHz) noise, uses the LM317. Should I be expecting this?
I never...
Thanks. Any suggestion for a 16-bit diff ADC besides the AD7688? My input comes from a logarithmic amplifier (AD606 ). It has a standard voltage output and a differential current output, and I'm deciding whether sticking with the standard output or using the differential one. I'm also...
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