Jeromed

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  1. Ok, I talked to an EE friend of mine and he explained the difference in bandwidth is NOT because of the BNC adapter but because of the probes you can use with them. The probes are specifically designed to minimize attenuation (loss of signal) and is one of the reasons the ground (black wire on the probe that should be attached to ground) is so short. And even though the two bnc channels share a common ground, you should always ground each probe individually as failure to do so requires a longer path to ground for the probe that does not have the black alligator clip attached. That is if you are tempted to use one probe ungrounded because the other probe is grounded, don't do it.
  2. Well that certainly helped. When I plugged 1+ 1- into a circuit I was testing, it changed what was happening, like it was introducing voltage. When I then added a black wire to ground (-) it starting acting normally again. And I do have the BNC Adapter as well. Do I just put ground on the probe to ground on the breadboard? Or do I need to also add a black wire from 2x15 flywire to the breadboard ground. Thanks for your help.
  3. Ok I found some specs from the Analog Discovery 2 National Instruments page: Analog Inputs • Two fully differential channels; 14-bit converters; 100 MSPS real-time sample rate • 500uV to 5V/division; 1MΩ, 24pF inputs with 9MHz analog bandwidth (30MHz using BNC Adapter Board) Arbitrary Waveform Generator • Two channels; 14-bit converters; 100 MSPS real-time sample rate • Single-ended waveforms with offset control and up to ±5 V amplitude • 9MHz analog bandwidth and up to 16k samples/channel (12MHz using BNC Adapter Board) I noticed that the bandwidth is a LOT less than the sampling rate, perhaps leading the user to think they are getting better information than is really available? (Yes I realize the bandwidth has a lot more to do with the amplitude degradation of the signal as the signal frequency goes up.) And again I don't understand why the BNC adapter ups the bandwidth as there doesn't seem to be anything special in the BNC circuitry. Is it the nature of the probes? All this is making a poor newbie's head swim.
  4. That post basically says I need a common ground but it does NOT say how to do it. So do I simply connect a ground wire (not one of the four scope wires) from the 2x15 flywire to the ground on my breadboard? Do I still need to run my breadboard ground to earth ground through my linear power supply? Again, do I simply connect the BNC ground to breadboard ground? Which basically states this that started the whole question in the first place: I realize all of this would be a lot easier if I simply used the power supply from AD2 (as I assume everything would now have a common ground) for my breadboard but the experiments I'm currently going through all require 9 volts thus the linear power supply as I got tired of changing batteries. Any help for a poor befuddle newbie would be appreciated.
  5. I know I read somewhere the specs on the scope are different depending on whether you have the BNC adapter or not but I can't find a definitive answer. Can someone please supply the with and without specs? And why would the BNC adapter make any difference on the scope specs? According to the schematic, the only thing different (if you use the DC jumper) is that the + side of probe connections are shorted to signal ground through a 27M Ohm resistor.
  6. I'm thoroughly confused by the note in the Analog Discovery 2 Reference manual, Section "2. Scope" about having a common ground reference. I understand (at least I think I do) about the dangers of floating ground but I'm not sure how to fix it. My setup at present is a breadboard with power supplied by a linear DC power supply usually set to 9v (I got tired of replacing 9 volt batteries). The power supply has - terminal, + terminal, and Earth Gnd terminal. Presently I'm powering my board with the + and - terminals, treating the - terminal as ground. The Analog Discovery 2 (AD2) is being powered by a usb port on a laptop. Since the power to the laptop is being supplied by an AC/DC brick, I have no idea what the ground is on the AD2. Is it simply a matter of taking a ground wire on the 2x15 fly wire and plugging it to the - terminal via the breadboard? Should I take the - terminal on the power supply and short it to the earth ground? Or should I be looking at the solution mentioned in the note above: Universal Serial Bus (USB) Peripheral Isolator Circuit http://www.analog.com/en/design-center/reference-designs/hardware-reference-design/circuits-from-the-lab/cn0160.html#rd-overview Thanks in advance for your help.
  7. Coming back to electronics after a college introduction course to electromagnetism decades ago. We got as far as LCR circuits which are an integral part of radio circuits (as I understand it) but not how they area actually used by radio circuits. I'm aiming towards understanding radio circuits. Of course I've gone hog wild with parts and tools (including the Analog Discovery 2) as a result of buying "Make: Electronics" by Charles Platt. Hoping this will eventually get me to my goal.
  8. I'm a newbie to the electronic fields though I had college introduction to electronics decades ago. I blithely took the statement that the Scope channels 1 & 2 were fully differential. I cooked a pnp transistor and nearly set a probe on fire until I figure out the grounds where shorted. In particular, if you have 2 probes, you should really only ground one of them to the circuit for this very reason!!!!! For someone getting up to speed again, you need to gently guide us. Statements like AD needs to be grounded in the same was as the circuit doesn't really help. More explanation is needed. And why are scope probes single ended (and just exactly what does that mean?). The major reason I got the probes is that 1) I thought they would be easier to use for testing circuits as they have grabbers and 2) I read somewhere (can't remember where) that the probes have a higher sampling rate. I agree with the original poster that this is a MAJOR safety issue.