On Monday 12 April 2004 04:31 pm, Alex Karasev wrote:
Hi,
I'd like to build a good quality portable/compact mic pre for field
recording, that would be powered by a small battery (9V or other
compact battery types), and provide phantom power for the balanced
condenser mics.
A 9V battery isn't going to have that much kick to it, compared to other
types...
Analog Devices SSM2019 may be a good chip to base this on:
,2121,SSM2
019,00.html
I would just use the simple datasheet diagram for the chip and
phantom power hookup.
What's left is the power supply that could turn a 6...9V battery
input voltage into a +/- voltage to power the SSM2019 chip, and
provide 15...48V phantom power to the mic. The Analog Devices
includes a passive component hookup diagram to make +/- 48V phantom
power available out of a +48V power supply.
That 48 volt requirement is typically what's supplied at the mixing console,
and then there are series resistors at both the console and mic ends, which
means that you can probably get by with a lot lower voltage.
So my voltage requirements are:
+15...+48V for phantom power
+ AND - (identical) 6...16V to power the SSM2019 chip.
Any suggestions on creating these voltages from a single +6V...+9V
battery? I do not want to have multiple batteries.
Do you mean you don't want multiple cells? I hope that's not what you're
saying here.
I have a DC/DC converter that, when fet +5VDC on input, can produce -
10 Vdc, -19 VDC, -26 VDC. I don't think I can just reverse the
battery supply input and turn the - outputs into +, as the outputs
are relative to ground common with input (plus there may be
polarized caps in there).
Phantom power shouldn't have any common connection with ground, anyhow, it's
that voltage between the two balanced lines. I don't know how you're going
to do this without multiple batteries, unless you get some sort of a small
switcher going that actually uses a transformer to get you away from that
ground connection.
