[sdiy] Running off a DC insted of AC 'wall wart' Any issues i should be aware of?

[Ken Stone]

The only forseeable issue to running low voltage (transformerless) AC
circuits from DC is to do with the rectifier. If you have a bridge
recitifier in there, the 0V line internal to the sequencer will be 0.6 volts
above 0 volts, meaning that plugging it in to anything on the same
accumulator that uses true zero, will result in power flowing through the
signal wire shields.

Of course if the rectifier is set up to do +/- VE via half wave
rectification from the AC source, you are stuffed.

Ken


>Hi there,
>
>I have a couple of MAM sq16 sequencers.  The power adapters that i got with
>the units are 12v AC ones.
>
>Now i suspect that, being digital devices, the whole lot probably runs off
>+5v DC inside.
>
>Opening up the box i see a 5v fixed voltage regulator strapped to a big
>heatsink.
>
>The sequencer seems to run fine off 9v DC from my brief test.
>
>I dont have the schematics, and havent even taken it appart enough to see
>the underside of the dual sided pcb.
>
>So, my question is:
>
>Is there any reason why i shouldnt continue to run it from a DC supply?
>Could there be any 'time bomb' type failures?
>
>Of course, this is all leading to me wanting to run it off a 12V SLA battery
>(yes, i know with the regulator, it wont be the most efficient way of doing
>it, but im not too bothered about that)
>
>Thankyou once again,
>
>Julian
>
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or ken at cgs.synth.net
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
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