[hpsdr] Demeter: Modularity

[Henry Vredegoor]

Hello Jeroen, All,
 
As to the question of if there should be a number of smaller boards or one
(or two) bigger boards, I think it would be the best option if we want
optimal flexibility and scalability.
On the other hand a single board with all the different regulators and
control processor on it has the advantages of being compact and the easier
interconnections between them.
 
I don't know what the aim is for the upper limit of the
currents/voltages/power for the different regulators planned for Demeter and
the resulting total dissipation that goes with these.
I could imagine that you would like to dissipate the heat to the outside of
the HPSDR enclosure using external heatsinks (avoiding noisy ventilators)
 
All that said. a number of questions/remarks that come to mind:
 
 - Will these boards have external power devices that need to be mounted
off-board (e.g. the linear regulators)?
 - Could one scale up for more current? (more power devices etc.), What
about regulators in parallel for higher current?
 - Could one add more voltages (regulators)? 
 - Would separate boards give more options for EMI suppression (earthing,
shielding, mechanical) ?
 - Mechanical mounting 
   -  Attached with their power devices directly to an (external) heatsink? 
     Running longer wires to an external  power device on a heatsink is not
a good idea, especially not for a switcher... ;-)
   - Have a particular regulator as close as possible to the attached user
(e.g. a power amp)?
 - Scalability:
    - With a linear regulator it is relatively easy to increase the output
current; you could have a low power board for a limited current and scale up
by adding external power devices
    - This is not the case with a switching regulator as far as I know.
      This would require besides adding a more high power switcher device
also at least exchanging inductors and capacitors with higher power versions
and other C and L values?
 
I think some of these aspects are good reasons to have regulator board(s) to
be separate ones?
 
I am aware of the fact that this makes the internal wiring more difficult
though..
 
The PSU controller board containing the microcontroller I think should be a
separate board anyway.
That could even be on ATLAS for easy connection to backplane signals for
e.g. voltage monitoring, Power Good signal etc.?
 
So I think the answer for me in general would be "YES!!"
 
 
73's,
 
Henry.
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