I've been working in the same thing BUT I don't want anyone who builds it to need a PCB. And I want the firmware to load over USB so there is no need to ship programmed chips or deal with external programmers. I think I can get the cost below $20. That said I doubt I'll get 1E-13 performance out of my Rb.
My little Arduino based controller has been running now for a couple months and keeping a crystal in lock. The board has a pins left over for a serial port that I'll hook up to the Rb. The trick to getting the cost down is NOT to do a custom PCB. Take advantage of one of the uP development boards and then for under $5 you get the USB interface, D/A and A/D, serial ports, timers and quite a bit of logic all 1/3rd the size of a credit card. On Thu, Jun 19, 2014 at 12:57 AM, Jan Boutsen <jan.bout...@telenet.be> wrote: > Count me in for an assembled and tested board. Great project. > Jan > > > > > ----- Original Message ----- > From: <ewkeh...@aol.com> > To: <time-nuts@febo.com> > Sent: Wednesday, June 18, 2014 8:49 PM > Subject: [time-nuts] FE5680 GPS Disciplined Controller > > > > FE5680 GPS Disciplined Controller > With all the FE 5680 rubidium oscillators being used as door stops out > there some of us decided to develop a GPSDO for it. The main question we > have: > Is there sufficient interest among time nuts for a discipline controller > for the FE5680 to make it available? Looking at the postings over the last > two years I am not so sure. > The construction and preliminary testing of a Brooks Shera style GPS > discipline controller for the later version (6.81e-13 resolution) of the > FE5680 > has been completed. We are trying to determine the number of people that > would be interested in obtaining an FE5680 discipline controller (if there > is > sufficient interest about $45 a kit shipping included, $75 for an > assembled and tested board, international orders for an additional $5) > when > it is > released. > We are also looking for three Beta testers that would be willing to > purchase, assemble, and test our Beta release controller kit with their > own > FE5680A and GPS receiver or Tbolt and provide feedback. Please send an > email to > _EWKehren@aol.com_ (mailto:ewkeh...@aol.com) Subject Time-Nuts FE 5680A, > if you would be interested in being one of the three Beta testers. A key > requirement is the willingness to get to it right away, the board assembly > takes about 30 minutes. Instrumentation to measure results is also a > requirement. We obtained impressive results using a cheap ublox 6M > receiver. > > The FE5680 GPS discipline controller is a small (2” x 2”) board using 8 > DIP’s and 1 SOT23-5 package powered by +5v with 0.1” headers for all > inputs > and outputs. Our plan is to have the kit supplier solder in the only SMD > device on the board. A GPS receiver 1PPS and 10 MHz sine from the FE5680 > feed the board with two 9600 baud serial ports sending TTL level tuning > commands to the FE5680 and receiving commands from and sending status data > to a > PC for data logging and system control via a simple terminal program. > In the chip count are two opto couplers that allow the use of isolated TTL > to USB conversion. These USB adapters are readily available and furnish > the 5 V necessary for the secondary of the opto circuit. An option is to > not > use the opto couplers and send the PIC TTL level RX and TX into a TTL to > RS232 adapter. Another option is to use a TTL to RS232 converter after the > opto couplers but then an external 5 V source would have to be supplied > for > the opto couplers. > As I mentioned before to get best performance from the FE5680 temperature > control is a must and after much fan and metal work I realized that a Lap > Top heat pipe is the easiest lowest cost solution. Comments appreciated. > As > an alternative the temperature correction needs to be disabled. Otherwise > two control loops fight each other. If you look close on page 7 of the > brochure temperature stability from –10 to +60 C looks good but a closer > look > and you see 4 E-11 changes over small temperature changes in the -10 to 60 > C range. Extensive analysis has been done on the FE 5680 A and maybe some > one can tackle that problem. Please look at what N5TNL did. It is attached > and click on his link. The FE 5680A does have a 4 channel MAX 1246 ADC and > most likely it is used to monitor temperature. > Also mentioned before the FE 5680 output is not the cleanest, I did > observe it and some one posted the attached. I apologize but my records do > not > show who did, so if you posted the data please come forward. For serious > applications where you are using it as your main reference a clean up like > the > Morion MV89 or HP 10811 should be considered. > This addition is not required for beta tests but temperature control will > help. > I am also enclosing the express PCB layout, be free to use it but it would > be more economical to do a group buy if there is enough interest and some > one steps up to kit. > Bert Kehren > To not exceed the attachment limit the plot will be a separate posting > > > > > > > > > > ---------------------------------------------------------------------------- > ---- > > > > _______________________________________________ > > 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. -- Chris Albertson Redondo Beach, California _______________________________________________ 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.