Homebrew 3 Channel Pure SIN Generator ( 0 ... 60MHz )

[BEP]

Thanks Bep, when it comes to writing a desktop computer interface (to log and maybe display scan data etc) then your expertise could be good.

Most of my time spent on this project will be software. The hardware is all pretty much plug and play modules. Of course I´ll have to fire up the soldering iron a little and also make some enclosure for it.

Stay tuned as I develop I´ll post more, probably post a short vid demoing the user interfaces main screen soon.

If required, I can hack or create PC drivers as well 

[otto]

Hello all,

@Yucca

very nice "monster" but ... it will NOT make the coils "happy".

Otto

[Yucca]

Hello all,

@Yucca

very nice "monster" but ... it will NOT make the coils "happy".

Otto

Hi Otto, why not? are you thinking square waves are needed? or maybe PWM?

If so then I could feed the outputs through digital circuitry and FETs in order to get square waves and maybe PWM from 10...90% by using comparator. My frequency in that scheme would be limited to 10...20MHz because of FET and driver speed. Of course I would still have up to 3D sweeping capability.

It will be nice for me to have a true calibrated signal source and I can make use of 1channel for lots of other things, I decided to do 3 channel because the modules are not that expensive considering the spec.

Yucca.

[Yucca]

If required, I can hack or create PC drivers as well 

Now that might be very handy! Thanks for the offer BEP!

The micro board has a FT232RL USB to Serial UART chip on it:

http://www.ftdichip.com/Documents/DataSheets/DS_FT232R_V204.pdf

[Peterae]

Hi Yucca

I think you are going to have trouble syncing them together, this is from the data sheet and it specifys that a master clock should feed all 3 DDS chips.

Note: For those who may be operating multiple AD9851 evalu
a tion boards from one computer, a MANUAL FREQUENCY
UPDATE option exists. By eliminating the automatic issuance
of an FQ_UD, the user can load the 40-bit input registers of
multiple AD9851s without transferring that data to the internal
accumulators. When all input registers are loaded, a single
FREQUENCY UPDATE pulse can be issued to all AD9851s.
A block diagram of this technique is shown in the AD9851 data
sheet as a quadrature oscillator application. This single pulse
synchronizes all the units so that their particular phases and
frequencies take effect simultaneously.

Proper synchronization
requires that each AD9851 be clocked by the same reference
clock source and that each oscillator be in an identical state while
being programmed. RESET command ensures identical states.
When manual frequency update is selected, a new box labeled
FREQUENCY UPDATE will appear just above the frequency
sweeping menu. Clicking the box initiates a single FQ_UD pulse.


The good news is that you should be able to remove all three clock oscillators from each DDS board and connect a small board to all 3 clock pins on each DDS board as they have provided plated through the holes for pin osc chips as well as the used SM osc modules.
For true phase syncing you will need the track length the same to each DDS chip.
You will need to issue a frequency update to all DDS chips at the same time as said above.