| ??? 03/12/06 21:20 Read: times |
#112028 - Update Responding to: ???'s previous message |
I'm still using same single sided PCB and things are getting better.
I removed two 20 MHz oscillators and replaced them with only one 50MHz oscillator for both DDS ICs. I removed the lousy filters as suggested by Kai and replaced the output 200R pots by 10k pots because they seem to be overloading the DDS. I'm producing output frequency of 10 to 12 MHz with good results. I have some harmonics but they are +- 5MHz away which could be filtered easily. Still working on the LCD user menu although I finished the frequency calculation algorithm. Both channels are working now every single time and on every reset press without introducing the 47 R resistors on the clck and data busses. I like the timer concept in the dspic, you load a period register with required value, once match occurs timer resets itself and no need to reload. it makes life easier. Visual initializer saves hours on digging into datasheets. Mahmood |
| Topic | Author | Date |
| AD9835 noise problem | 01/01/70 00:00 | |
| noise | 01/01/70 00:00 | |
| Recommendations | 01/01/70 00:00 | |
| quick fix? | 01/01/70 00:00 | |
| Maybe | 01/01/70 00:00 | |
| Transmission lines | 01/01/70 00:00 | |
| 5MHz? | 01/01/70 00:00 | |
| Spectrum analyser | 01/01/70 00:00 | |
| It's ground noise | 01/01/70 00:00 | |
| ground noise and groundhogs | 01/01/70 00:00 | |
| Harmonics as well | 01/01/70 00:00 | |
| comments | 01/01/70 00:00 | |
| Why separate the analog & digital gnds? | 01/01/70 00:00 | |
| Splitting the ground plane | 01/01/70 00:00 | |
| Evaluation board | 01/01/70 00:00 | |
| thin ground? | 01/01/70 00:00 | |
| that is why you use star | 01/01/70 00:00 | |
| Ground wire in parallel | 01/01/70 00:00 | |
| and a twisted pair? | 01/01/70 00:00 | |
| Would do! | 01/01/70 00:00 | |
| does not exist, Jan if you used twisted | 01/01/70 00:00 | |
| The clock signal? | 01/01/70 00:00 | |
| oh well | 01/01/70 00:00 | |
| Indeed | 01/01/70 00:00 | |
| is there a way... | 01/01/70 00:00 | |
| Hardly | 01/01/70 00:00 | |
| unfortunately not | 01/01/70 00:00 | |
| twisted pair | 01/01/70 00:00 | |
| is that not obvious | 01/01/70 00:00 | |
| No ground traces, but patches | 01/01/70 00:00 | |
| the bane of many | 01/01/70 00:00 | |
| Why 1 or 2 layers | 01/01/70 00:00 | |
| it's nice! | 01/01/70 00:00 | |
| No Secrets | 01/01/70 00:00 | |
| DALO 2M professional | 01/01/70 00:00 | |
| UV ink Problem | 01/01/70 00:00 | |
| Mixed method? | 01/01/70 00:00 | |
| No Need for DALO | 01/01/70 00:00 | |
| CE | 01/01/70 00:00 | |
| Single step mode | 01/01/70 00:00 | |
| If you want... | 01/01/70 00:00 | |
| mmm | 01/01/70 00:00 | |
| Dreaming | 01/01/70 00:00 | |
| LAYOUT | 01/01/70 00:00 | |
| 100nF caps | 01/01/70 00:00 | |
| 100nF ? | 01/01/70 00:00 | |
| ok | 01/01/70 00:00 | |
| Some checks | 01/01/70 00:00 | |
| It's my daily job! | 01/01/70 00:00 | |
| Unfortunately, no | 01/01/70 00:00 | |
| simulate double-layer | 01/01/70 00:00 | |
| Seperate Analog and Digital Supply | 01/01/70 00:00 | |
| RLC-filters don't help? | 01/01/70 00:00 | |
| separate | 01/01/70 00:00 | |
| And... | 01/01/70 00:00 | |
| Seperate Supplies | 01/01/70 00:00 | |
| Evaluation board | 01/01/70 00:00 | |
| No not that one... | 01/01/70 00:00 | |
| Curly | 01/01/70 00:00 | |
| OT: Hair | 01/01/70 00:00 | |
| lets have pictures | 01/01/70 00:00 | |
| No no... | 01/01/70 00:00 | |
| http://www.k6ese.com/Mar_Vista_Shack.htm | 01/01/70 00:00 | |
| but it is relevant | 01/01/70 00:00 | |
| No wonder... | 01/01/70 00:00 | |
| waveforms | 01/01/70 00:00 | |
| Link to DDS page | 01/01/70 00:00 | |
| Add the second stage... | 01/01/70 00:00 | |
| Filter components | 01/01/70 00:00 | |
| clock | 01/01/70 00:00 | |
| What clock | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| Sampling theorem | 01/01/70 00:00 | |
| But... | 01/01/70 00:00 | |
| Can't find it now | 01/01/70 00:00 | |
| Ground of probe? | 01/01/70 00:00 | |
| even better | 01/01/70 00:00 | |
| Good trick! | 01/01/70 00:00 | |
| same point | 01/01/70 00:00 | |
| Both | 01/01/70 00:00 | |
| I feel strong now! | 01/01/70 00:00 | |
| Funny! | 01/01/70 00:00 | |
| Depends... | 01/01/70 00:00 | |
| Oh Dear | 01/01/70 00:00 | |
| NO analog outputs | 01/01/70 00:00 | |
| since there is no schematics presented | 01/01/70 00:00 | |
| Publishing failed | 01/01/70 00:00 | |
| then give a link to an ORCAD drawing | 01/01/70 00:00 | |
| Schematics | 01/01/70 00:00 | |
| corrections | 01/01/70 00:00 | |
| Big test | 01/01/70 00:00 | |
| Try This Schematic... | 01/01/70 00:00 | |
| one more problem | 01/01/70 00:00 | |
| I miss the second 300R resistor | 01/01/70 00:00 | |
| Terminating Resistor. | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| University of Kai | 01/01/70 00:00 | |
| Keep us informed... | 01/01/70 00:00 | |
| of course | 01/01/70 00:00 | |
| Update | 01/01/70 00:00 | |
| Eager to know | 01/01/70 00:00 | |
| Me too | 01/01/70 00:00 | |
| Autoreload | 01/01/70 00:00 | |
| Current source output | 01/01/70 00:00 | |
| Electronic World Feb 06 | 01/01/70 00:00 | |
| Superb! | 01/01/70 00:00 | |
| No surprise | 01/01/70 00:00 | |
| AD9835 Cycles | 01/01/70 00:00 | |
| Solid Ground Plane Update!!!!! | 01/01/70 00:00 | |
| Very nice results! | 01/01/70 00:00 | |
| Low frequency | 01/01/70 00:00 | |
| SLIGHt correction | 01/01/70 00:00 | |
| OPA27? | 01/01/70 00:00 | |
| Cross talk on PCB tracks | 01/01/70 00:00 | |
| Have a look at this plot | 01/01/70 00:00 | |
| Interesting question | 01/01/70 00:00 | |
further interesting question | 01/01/70 00:00 |