10 - How to Measure DC Amperage With an Oscilloscope скачать в хорошем качестве

10 - How to Measure DC Amperage With an Oscilloscope

Please pay attention to the description next to the chart directly following the walk-through on the schematic in this video. Continued below video description: This video describes a method I am implementing for measuring DC Amperage on an Oscilloscope using a Shunt Resistor. There is a lot of detail in here on how to sample the current, as well as the measurements on losses/inefficiencies in this method. When all the factors are considered - being able to display the measurement on an Oscilloscope gives a window in to current draw that you will never achieve with any numerical meter as the 'scope plots current (a voltage representation of it) over time - out to as wide of time base as you can get your 'scope to view. Continued from above: The only word that is blocked is "oscilloscope" (text window underneath came through in exporting, I didn't think it would with nothing typed in it but it did). I may work on a follow-up video detailing that description in the video. The key thing to pay attention to is the DC coupling of the probes with the 'scope readings and the issue of ripple. A common calibration for shunts is 75mV/full scale (20, 50, or 100a DC ratings can be this). There may be many other values shunt-based DC amp meters use. 75mV is quite tiny compared to the several hundred mV to a couple of V (2000mV=2V) I am working with. The ripple I am seeing on my 'scope makes it to where it is impossible to resolve lower voltage ranges. If I go to a 200mV/div scale the traces get 2-3x wider than you see in the video right there - and to resolve 75mV/full amp scale of a conventional shunt I would have to have a scale on the 'scope down to 20-50mV/div - 1/10th of what I am using. So again - whether it's my 'scope or just that the DC coupling in general is "noisy" (hence why I added the caps) - it is impossible on my set up to resolve lower voltage differences that would be achievable with lower resistance shunts. That lower resistance would, in turn, mean less power loss and higher efficiency. It just isn't achievable on my gear. An alternative would be to make a regulated and calibrated active board to amplify a tiny voltage difference to a level that would be able to be resolved on the 'scope - back to that 500mV/div, so within, say, 3 volts for full scale, as opposed to 75mV. That is a lot more complicated than data collection and plotting known values from which to post-calibrate as is described in this video in the charts - specifically the heat loss and % power loss at the end of the spread sheet segment (around the 29min mark).