[sdiy] Getting 48v from +/-12v??

[Tom Wiltshire]

It depends how much current we're really talking about here. "A lot" doesn't really give us a spec to work with.
A bit of a search turned this up:

"2 mA is not even very much by modern standards. A Neumann TLM 103 draws 3 mA; Schoeps CMC 5-- and 6-- microphones draw about 4.5 mA; Shure KSM-series mikes typically draw 5.5 mA; many CAD Equiteks draw 8 mA. The maximum allowable current per microphone is 10 mA, at which point the voltage at the microphone will have dropped to a mere 14 Volts or so--more power is dissipated in the phantom resistors than is available to be used by the microphone! But there are some highly regarded Earthworks microphones which draw that much current, for example."

from http://www.mandolincafe.com/forum/showthread.php?7362-Phantom-Power-Current-Draw-in-New-Mics

That suggests you might be looking at 10mA as a reasonable top end. I'd have thought that's ok for a buck-boost, but I haven't checked the specs of those. Noise from a switched convertor would be more of a worry for me, since we're going to be pre-amping some small signal coming out of this mic and any noise along with it.

HTH,
Tom


On 21 May 2013, at 16:52, cheater00 . <cheater00 at gmail.com> wrote:

> Not the best idea if you want a lot of current.. don't do it, just say NO!
> 
> If you want 48v DC then you need 0 and some AC voltage a bit above 48,
> so that the regulator has something to work off.
> 
> On Tue, May 21, 2013 at 5:50 PM, Martin Klang <mars at pingdynasty.com> wrote:
>> 
>> On 21 May 2013, at 16:31, dan snazelle wrote:
>> 
>>> So my question would be what sort of transformer to look for?
>> 
>> what you need is something like a buck-boost converter, like the one Barry linked to.
>> 
>> hth,
>> 
>> /m
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