Let me add my thanks. My knowledge of FPGA's is about the same as my knowledge of the female of our species. Is it possible to read the program that's been entered into the chip? I'm not clear as to the data flow in this beast. If the control loop is indeed digital, then there's a PID controller in software? It's possible then to control the frequency as some want to do with the beast as it is, using an Arduino or Picaxe or some such to adjust the frequency with an external loop and digital corrections via the rs232 rather than all this crude analog resistor stuff :-) Don
ewkeh...@aol.com > Pete > Thank you, I will look at its some time in the future, right now I let > it > cook for a couple of weeks undisturbed and than I may cut the trace that > seems not to do any thing. If you have a 100 MHz scope it will trigger > on any > pulse in this unit unless your scope is defective. I think there are > features hardware wise in this unit that can be activated at > manufacturing > depending on price and demand. I am sure you are aware of instruments > that a > hardware wise the same and cost any where from $15 000 to $40 000 the > only > difference is the software imbedded and many times you can buy an > upgrade. > Bert > > message dated 11/18/2011 10:26:02 A.M. Eastern Standard Time, > bell.pe...@gmail.com writes: > > All the pins have things connected to them - but pin 6 seems a little > strange - it's connected to the 'ACT240 (in fact, it goes through 3 > sections of the chip in series!) and finally to the xilinx chip - but > none of these signals ever appear to do anything and the output is > just constant high. It's possible that this the pulse is just > extremely short - the fastest scope I have at home is only 100Mhz - > but I would have expected to be able to tirgger on it at least. > > Regards, > > Pete > > > On Fri, Nov 18, 2011 at 9:09 PM, <ewkeh...@aol.com> wrote: >> Pete >> Thank you for doing all the work. This is great info and will help >> all > of >> us that want to discipline the beast. One more question, since you >> have > done >> so much testing is there one pin on the connector that has nothing >> connected to it? >> Thanks again Bert Kehren >> >> >> In a message dated 11/17/2011 9:59:14 P.M. Eastern Standard Time, >> bell.pe...@gmail.com writes: >> >> OK, I just managed to get some spare time to have a look at this, >> and >> here are some conclusions: >> >> 1) The fine frequency adjust pot is not connected to the c-field >> circuit. All the connections to it go across the board to the >> MAX1246 >> ADC chip. The track is wired between ground and the vref output on >> this chip and the wiper goes to a little pi filter (ceramic cap, >> 100K, >> 1uF tant) that feeds channel 1 (pin 3) on the ADC. As far as I can >> see, it goes nowhere else. >> 2) The c-field current is fixed. The circuit is very simple - there >> is a 5.1V reference generated using a zener and a 681R resistor to >> the >> 8.8V and this is fed into a potential divider consisting of a pair >> of >> 120K resistors. The centerpoint of this divider is connected to pin >> 5 >> (+ve input) of a TLC27M4BI - the output of this amp (pin 7) is >> connected via a 270R resistor to pin 2 of the FPC connector and hence >> to the c-field coil. The return side of the coil (pin 1 on the FPC >> connector) connects to pin 6 (-ve) of the opamp and via a 620R >> resistor to the 5.1V reference. >> >> If there is any other input to this circuit, I have not been able to >> find it, despite probing all over the board. >> >> Conclusion: >> >> This version carried out the fine frequency adjust digitally by >> changing the reload values on the DDS chip - the reason the pot does >> does nothing in this specific model is that the DDS trim is now >> being >> carried out over the RS-232 port and as a result the pot value (if >> it's being read at all) is not being used for anything. >> >> Adjusting the c-field still works, though - if you connect a DC >> supply >> set at about 2.55V via a high value resistor (I used 100K) to pin 5 >> on >> the TLC27M4BI next to the flex cable connector then you can trim the >> frequency by adjusting it. >> >> Regards, >> >> Pete >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." R. Bacon "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
