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external battery question / wall warts.

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RogerJ

New Member
Hi. I'm interested in audio recording and I have a few bits of gear that do not have an IEC mains connector, but instead use dreaded "Wall wart" PSUs.

Some of these have needpower input from an AC output wallwart. For example: Joe Meek MQ3 need 12v ac and M-Audio Audio Buddies require 9v ac. Both are microphone pre-amps.

I'd like to be able to take these out as "field" equipment and my question is about feeding DC from a battery/s into gearlike this. Is it safe to do so? I'm making an assumption - that could be challenged! - that the first thing the AC will see in this type of gear is a bridge rectifier. Therefore, without worrying about polarity the dc may pass though the bridge and the gear should work normally.

If DC was put in there's also the question of how much. If 12v ac was required then, assuming a conventional rectifier cct, the raw dc produced internally could be approaching 16v (depending on the load and Cap size)

So would you feed in, say 15v to the 12v ac input plug ?? I havn't dared try this out in case I blow something up so am posting this question in hopes of provoking some useful replies/thoughts..
 
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Sceadwian

Banned
The AC may be required to get a negative voltage internally, if you feed it only a positive DC supply it won't have a negative rail, and could fail pretty spectacularly, or just not work. You'd have to disassemble the devices and take a look at their power handling circuitry to determine if you could feed it straight DC. If you were brave enough to do so and took some decent pictures of both sides of the board people here might be able to help.
 
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