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K Murty
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Hello.
How would this be done? Using a step up transformer?
How would this be done? Using a step up transformer?
I am not measuring anything, but I am wondering how one would measure AC waveforms that are very small in magnitude, even smaller than the micro prefix. I know transformers are used to step down high voltages so they can be measured by voltmeters and for safety. So I was wondering if the opposite use, to step up small voltages and currents so they can be measured by instruments, is a use for transformers?scottdave said:Can you be a little more specific? How small? A transformer will only work with AC, not DC. What is it that you are measuring? If you have access to an oscilloscope, that might be a way.
For audio signals for example;K Murty said:So I was wondering if the opposite use, ...
When a transformer is used to step up the audio voltages from a microphone or pickup, it steps up the noise voltage that comes with it.
dlgoff said:For audio signals for example;
from http://www.vias.org/crowhurstba/crowhurst_basic_audio_vol2_033.html
Excellent point.When a transformer is used to step up the audio voltages from a microphone or pickup, it steps up the noise voltage that comes with it.
I will reply in some time.berkeman said:Excellent point.
@K Murty -- can you say a bit about the small signal noise sources that you've been reading about, and how to maximize the signal-to-noise ratio (SNR) when dealing with small signals in the presence of noise sources (natural and human-generated)?
Thanks.K Murty said:I will reply in some time.
berkeman said:Excellent point.
@K Murty -- can you say a bit about the small signal noise sources that you've been reading about, and how to maximize the signal-to-noise ratio (SNR) when dealing with small signals in the presence of noise sources (natural and human-generated)?
I would think cooling!berkeman said:Thanks.
Hint -- the main natural noise source I've had to deal with is thermal electrical noise. That should help your search terms...
From the wikipedia link,berkeman said:We use a sigma-delta receiver with decimation to achieve about 80dB quiet line receive performance...
https://en.wikipedia.org/wiki/Delta-sigma_modulation
I'm trying to visualize, circuit wise, how this would be applied to motor controllers. I'll be doing some searching but if you know of any good sources, could you provide them here? However this may be a little off-topic.Primarily because of its cost efficiency and reduced circuit complexity, this technique has found increasing use in modern electronic components such as DACs, ADCs, frequency synthesizers, switched-mode power supplies and motor controllers.
Integrating ADC does a wonderful job. If you integrate for one line cycle you have really suppressed line frequency interference because integral of a sinewave is zero... but it's slow. old jimK Murty said:I think the integrating A D converted is key here...
Dang Jim. Where do you find this good stuff? This quote from the tutorial is priceless IMO.jim hardy said:Tutorial here, don't be scared off by the math on first few pages...
http://www.ti.com/lit/ml/slap103/slap103.pdf
Many engineers, used to getting steady values from their low-resolution converters, are dismayed when they
find the output value of a 24-bit device fluctuating madly in its least significant bits. It’s not hard for an engineer,
long used to working with low-resolution devices, to feel a bit cheated when he finds out that a 24-bit device isn’t
really 24 bits when noise is taken into account!
You da man.jim hardy said:We installed a 14 bit (15 including sign) ADC for our computer because its drift and nonlinearity were so small relative to our 10 bit need that it could go for years between calibrations.
The best method for measuring very small voltages and currents is to use a high precision digital multimeter (DMM). These instruments have a high input impedance and can accurately measure small changes in voltage and current.
The accuracy of measurements of very small voltages and currents depends on the precision and sensitivity of the measuring instrument, as well as the quality of the connection and the stability of the circuit. It is important to use proper techniques and equipment to ensure accurate measurements.
Yes, environmental factors such as temperature, humidity, and electromagnetic interference can affect the accuracy of measurements of very small voltages and currents. It is important to control for these factors or use shielding and filtering techniques to minimize their impact.
To protect your measuring equipment when working with very small voltages and currents, it is important to use proper safety measures such as grounding and insulation. In addition, using high quality and properly calibrated equipment can help prevent damage to your instruments.
Yes, there are limitations to measuring very small voltages and currents. Some instruments may have a lower limit of detection or may not be able to accurately measure extremely small changes. Additionally, noise and interference can make it difficult to obtain precise measurements.