[sdiy] Alfa AS3350 power supply question

[Ben Bradley]

Those do look odd and contradictory. I looked up the CEM3350 data
sheet and (because apparently the AS datasheet is a copy) it also
shows the "Electrical Characteristics" table with +/-12V, so that's
surely the "Recommended" supply voltage. It also shows the same
maximum of +/-16V and the note that the total voltage should not
exceed 26V. The last note suggests the "actual" maximum is +/-13V.

To directly answer your question, if you used +/-15V I suspect 90 or
99 percent of them would work fine. But even so, I wouldn't do it, I'd
run them off +/-12V. That way, if several started going bad down the
road, I wouldn't be second-guessing if it was a problem of operating
them outside their voltage rating. I don't have a strong feeling about
them being powered by an op-amp or another regulator, either should be
fine.

And since you seem to be asking ... most 50/60Hz power transformers
have two identical secondary windings. I take advantage of this by
making them power two identical and independent 15V power supplies,
and only connect them with one's positive output going to the other's
negative ouput to get +/- 15V. This lets me use the same type
regulator for both supplies. I use the LM318 and appropriate resistors
to set output voltage. To get 12V from 15V, I could again use LM318's
with resistor values to get a 12V output from a 15V input.

On Mon, 20 Jan 2025 at 22:29, David G Dixon via Synth-diy
<synth-diy at synth-diy.org> wrote:
>
> Hey SDIY Team,
>
> I just bought 100 AS3350 dual SVFs for a massive project.  The datasheet is a bit strange.  In one place, it says that the supply can be from +/-3V to +/-16V.  In another it says that the total supply voltage should not exceed 26V.  On the diagram, it says that the supplies can be +3 to +12V and -3 to -12V.
>
> So, obviously, they are intended for +/-12V supplies.
>
> My question is this:  What do you think would happen if I used my +/-15V supply?  Would it a) work just fine, b) get too hot, or c) exploderate?
>
> Of course, I'll try it out, but if it works fine and doesn't get hot, is there some hidden catastrophe that will take me by surprise later?  The chip basically contains four exponential sources and six OTAs.  I don't really understand why it should be that sensitive to supply voltage.
>
> In a related question, if I want to provide a +/-12V supply for the chip, then what do you think about just dropping 15V to 12V and -12V through a couple of opamps and using that as the supply for the chip?  Everything else on the board is perfectly happy with the +/-15V supply.  Alternatively, I could use 78L12 and 79L12, but I'd rather avoid that if I could.
>
> Cheers,
> Dave Dixon
>
>
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