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Re: [Xylo-SDR] power
I'm not so sure we need +- 15volts, a long time ago when op-amps were not
tolerant of Vcc variations that was the standard power supply. Today most
op-amps will work fine with +-5V.
Power supplies now more commonly have +5V and +-12V so most likely that
will be what we end up with.
+12V is a nominal value, the analog cards will regulate that down to +-5,
or +-9 for noise elimination. The only place where it will be used is if
you have a card with a RF power amplifier, or a Auto tuner, those are
application that will use that voltage directly. Any decently designed
low power RF amplifier will tolerate 11V but will have slightly lower
output power, and most 12V relays will still work at 11 volts..
The +5 volts will consume a lot of current so regulating it from a 12
source will create a lot of heat, and internal parts like the FPGA's run
on 3.3Volts and 1.7Volts at high current, regulating those from 12 volts
would be insane, so like it or not a noisy switcher will be necessary, a
carefully chosen one, with noise suppression will eliminate the problems
both electrically and thermally.
At this point it has not been decided if the input to the power supply
will be 13.8 volts or a wall plug.
First well decide what voltages we need, then we can shop for power
supplies that will fit in the space that is affordable, that will
determine the power input options. It could well be that there could be
an option as to what the voltage in is by choosing what power supply to
stick in the box.
My personal preference is to use a 13.8 volt source as the input power,
but that will be quite limiting as to available power supplies. That way
the unit could run at the shack, or on a 12 volt battery system. But some
don't have a 13.8 Volt power supply in the shack, so they will not like
it. All my radios except for one run on 13.8 Volts so it's no problem for
me, I have several 13.8Volt high current power supplies around
At 09:45 PM 1/15/2006, you wrote:
a note on the +12, please make that
+11 to +15v so i can use solar and charging batteries or marine type
stuff with some margin. the +12 is to narrow. the +5 can be made
using a 7805 but the +- 15 looks like more noise generators making the
volts from +12. more comments ???
- ----- Original Message -----
- From: Eric Ellison
- To: 'Xylo-SDR
- Sent: Sunday, January 15, 2006 4:03 PM
- Subject: [Xylo-SDR] RFC - Powers
- Changed the subject in the
- I hope folks like Bill ? KD5TFD,
Phil ? VK6APH, Phil ? N8VB are designing their projects based on some of
the constants we are defining are NOT reading all this stuff based on
subject. Hopefully they WILL trust that we are commenting and deciding
and are keeping their project in mind.
- What powers do we want coming
into the MB?
- Do we want to create a power
board within the enclosure or have power source external to the
- I?ll kick it off.
- I would like to see us use the
?rest? of our 100 x 156 (ID) x 113 mm enclosure for a powers board.
- I would like to see a SINGLE 12
volt input to the back of the enclosure with other voltages derived from
that via DC-DC regulators.
- On project board regulators
should use the power supplied from this slide in board for component
power, from the buss.
- Thoughts for the ?rest of the
space? is take +12 Volt input from the back of the enclosure to a DC to
DC converter to supply:
- +12 V ( passthru from back panel
regulated, not highly filtered, unlimited current)
- 5 V
- +/- 15 V.
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