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Mahmood Elnasser
07/08/12 09:45
Read: 720 times
Sacramento
USA


 
#187888 - so far so good
Responding to: Richard Erlacher's previous message
Richard Erlacher said:
Did you build one of those circuits you discussed?

Working on it, but I tested the trigger with two channels with odd waveforms using old cct, one with modulated 1khz signal, the other 20nsec pulses synchronized with the rising edge of the 1khz signal, the good news is this scope does trigger on the little pulses unlike the cheap DSO.
How's the triggering? Do you have an attenuator on the output of your circuit so you can reduced the amplitude? How sensitive is this 'scope, i.e. what's the smallest voltage per division that it can reliably display? Can it trigger on short pulses of that magnitude?

I will do this test later on, but I think the answer is yes.
How about slowly rising waveforms, i.e. a waveform that rises at 1 volt/ms? Does it provide a crisp, clear display, or is it muddied by variations in the trigger voltage? (Nearly any instrument will have some ambiguity in its triggering.)

It works perfectly for slow rising signal, in fact you can measure the rise and fall time of the signal with crystal clear display.
How does it compare in these regards with respect to your old TEK 475?

My old tek475 is junk compared to this one. at high frequency my old tek display brightness becomes dim I can hardly see it, so I made my tek475 work as a component tester in my workshop while I'm having good time with my color dso!
What sort of probes did they provide, if any? Are they switchable 1x/10x types? Does the instrument recognize the impedance setting?

Yes they are good 1x/10x 300MHz probes with load capacitance of 12pF. The only setting in the scope for probes is the 1x/10x/100x/1000x probes, however the bad news is when I set the probe to 10x the rise time of the signal is degraded and I can no longer see fast rise edges.
There's lots of experimentation ahead, before you'll know what the 'scope really does, and how well.

TBH this is the best scope I ever had and I'm quite happy with it. my FPGA knowledge is rusty so I'm slowly catching up, I'm almost done playing with DCMs so that I can generate high speed signals to put this scope testing to the limits. Unfortunately the rising time of the scope is <= 1.4nSec as per datasheet, I want to test it with sub nano seconds signals.
I don't have modern high end DSO scope to compare it with but I think it is a good value for the money.
I will keep you posted.
Mahmood

List of 74 messages in thread
TopicAuthorDate
DSO for cheap!      Joseph Hebert      05/11/12 13:35      
   very good      Mahmood Elnasser      05/11/12 14:14      
      Limitations      Joseph Hebert      05/12/12 09:49      
         test results      Mahmood Elnasser      05/12/12 12:46      
            That's valuable information      Joseph Hebert      05/12/12 13:30      
         well, the fact is ..      Richard Erlacher      06/03/12 11:43      
            tektronix 475 comparison      Mahmood Elnasser      06/07/12 10:37      
               Really? Why?      Richard Erlacher      06/07/12 14:51      
               another double post ... sorry      Richard Erlacher      06/07/12 14:51      
   I think ...      Erik Malund      05/11/12 14:34      
      Application dependant      Mahmood Elnasser      05/12/12 05:55      
         Indeed      Andy Neil      05/12/12 09:10      
            It's still too low a bandwidth, wouldn't you say?      Richard Erlacher      06/03/12 11:50      
   just curious, Joe could you try      Erik Malund      05/11/12 14:36      
      Unusual with short pulses for hobbyist projects      Per Westermark      05/11/12 14:53      
         is the clock running?      Erik Malund      05/11/12 16:01      
      Sorry, but no I can't.      Joseph Hebert      05/11/12 16:42      
      10nSec Pulse      Mahmood Elnasser      05/12/12 12:59      
         "at random" means what exactly ?      Jim Granville      05/13/12 18:41      
            Answers      Mahmood Elnasser      05/14/12 07:41      
               more observations      Mahmood Elnasser      06/03/12 10:51      
                  It may not be the sample rate ...      Richard Erlacher      06/07/12 15:07      
                     digital vs analog      Mahmood Elnasser      06/08/12 15:34      
                        Don't get me wrong, here ...      Richard Erlacher      06/08/12 21:34      
                           poor mans's scope      Mahmood Elnasser      06/09/12 02:01      
                              Doesn't it depend on what THEY mean by bandwidth?      Richard Erlacher      06/09/12 20:58      
                                 20 nsec steps      Mahmood Elnasser      06/09/12 23:08      
                                    Well, one thing at a time ...      Richard Erlacher      06/10/12 11:43      
                                    Impulse Tests are better      Jim Granville      06/10/12 16:49      
                                       more capable scope      Mahmood Elnasser      06/11/12 14:03      
                                          I must have missed a step ...      Richard Erlacher      06/12/12 08:07      
                                             TEK475      Mahmood Elnasser      06/12/12 16:16      
                                                here's another alternative ...      Richard Erlacher      06/12/12 22:16      
                                                   DAC and pot in parallel?      Per Westermark      06/13/12 01:07      
                                                      Logically, not physically      Richard Erlacher      06/13/12 07:57      
                                                   new theory      Mahmood Elnasser      06/14/12 00:57      
   3MHz is rather poor Bandwidth ?      Jim Granville      05/11/12 16:51      
      ordinary      Erik Malund      05/11/12 17:20      
         Ther are many params needed      Jim Granville      05/11/12 18:21      
   "only" $200 ?      Andy Neil      05/11/12 23:59      
      Low cost oscilloscopes      Andy Neil      05/12/12 09:18      
         291 > 2*($199)      Joseph Hebert      05/12/12 09:45      
            It doesn't always work that way      Andy Neil      05/12/12 10:48      
               Once upon a time ...      Joseph Hebert      05/12/12 13:28      
   SDS8202      Mahmood Elnasser      06/14/12 13:58      
      Read all the "fine print' first ... and ask any questions      Richard Erlacher      06/14/12 20:31      
         bought it      Mahmood Elnasser      06/16/12 03:07      
            Please let us know how this works out for you      Richard Erlacher      06/16/12 04:19      
               datasheet      Mahmood Elnasser      06/16/12 05:26      
                  2mV/div - but min trig level?      Per Westermark      06/16/12 07:01      
                     Tests      Mahmood Elnasser      06/16/12 09:55      
                        24ns      Per Westermark      06/16/12 11:09      
                           and that's the crux      Erik Malund      06/16/12 11:41      
                              FPGA pulse Expander (edited)      Mahmood Elnasser      06/16/12 12:06      
                                 some love the mother, some love the daughter        Erik Malund      06/16/12 12:13      
                                 Here's omne fairly simple thing ...      Richard Erlacher      06/16/12 15:22      
                                 self calibtrate?      Jim Granville      06/16/12 20:42      
                                    interesting      Mahmood Elnasser      06/16/12 23:01      
                                       yes      Jim Granville      06/16/12 23:15      
                                          glurk      Jez Smith      06/17/12 13:33      
                                             DCMs      Mahmood Elnasser      06/17/12 14:49      
                                                Well....      Jez Smith      06/17/12 15:48      
                                                   I don't know where you're going with this ...      Richard Erlacher      06/17/12 21:25      
                                             xxxxx      Mahmood Elnasser      06/20/12 12:53      
                           333ps      Mahmood Elnasser      06/18/12 00:59      
      SDS9302      Mahmood Elnasser      07/05/12 10:32      
         So, how are you exercising this new 'scope?      Richard Erlacher      07/05/12 10:53      
            so far so good      Mahmood Elnasser      07/08/12 09:45      
               So far so good ...      Richard Erlacher      07/08/12 10:49      
                  rise time      Mahmood Elnasser      08/15/12 13:28      
                     The rise time indicates that high frequencies gets dampened      Per Westermark      08/15/12 16:26      
                     What does "bandwidth" mean?      Richard Erlacher      08/15/12 17:45      
                        good test      Mahmood Elnasser      08/30/12 15:09      
                           Perhaps you should repeat the test ...       Richard Erlacher      08/30/12 23:08      

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