| Richard Erlacher 06/13/12 07:57 Read: 222 times Denver, Co USA |
#187693 - Logically, not physically Responding to: Per Westermark's previous message |
Per Westermark said:
Richard Erlacher said:
HI wanted to use the DAC's in place of some of the pot's but in parallel with them, so the instrument could be driven by software if desired, but could also be hand-operated. Doesn't sound easy to have a DAC and a pot in parallel. The POT and DAC were separated by an analog multiplexer. The theory was that a switch could control whether the DAC's or the POT's were in use to set the various control voltages. It was very tempting to make it overly complex. I'm not even sure the thing was ever completed. You didn't consider using a rotary encoder to allow you manual control of the DAC?
No ... nobody thought of that. It was just a way for us to use those free samples of the MAX038 that we all seemed to have at the time. It looked like a really "pregnant" project. I was disappointed that the frequency topped out at 20 MHz, others were more concerned about the trouble in making the output voltage swing 15-20 volts to either side of common, as was usual with old-style signal generators. At the time, I was enamored of being able to phase-lock two generators (that's what the MAX038 is, after all) of different frequency, so I liked it. I had to phase-lock two, and sometimes three of the TEK FG504's that I had. ISTR that was in the early '90's ... We weren't terribly busy at the time. RE |
| Topic | Author | Date |
| 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 |