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

[mark verbos]

I'd look at the circuit in the top right corner of the Paia tube mic pre.
Or use a packaged DC-DC converter, which are often regulated. Looks like they don't come cheap in that voltage though. You might do ok with something like this 

http://www.mouser.com/ProductDetail/Murata-Power-Solutions/NMH0524DC/?qs=sGAEpiMZZMtwaiKVUtQsNc5yzZotoBjeh7%252bctzLi63g%3d

It's specced to be +/-24 volts isolated output, but if you put the -24 side to ground, the +24 will look a lot like +48.

Mark




On May 21, 2013, at 1:58 PM, Dan Snazelle wrote:

> This is to power 2 mics in a rack
> 
> I was thinking a dc to dc type circuit would provide ample current
> 
> 
> Thanks!!!!
> 
> Sent from my iPhone
> 
> On May 21, 2013, at 12:44 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
>> 
>> 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
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy