[sdiy] +/- 9v synth circuits

[harrybissell]

Two 9V batteries gives 18V... regulated to 12V thats 5V drop...
you are going to eat batteries.

I'd say that a 9V is good for about 180mA/hrs... so a 180mA load kills
the battery
in one hour.  90mA = 2 hrs etc...   I probably would not want to use 9V
batteries
for more than maybe a 20-30mA load.

(some folks on the list suggested that the 180mA/hr figure is way low.
I don't know
whose right. Maybe they get better batteries than me :^)

I have to look at the madmouse again (carefully) but i'd say offhand it
was not designed
with battery operation in mind ...

You need to really pay attention to what you're doing in battery
operated design.  Either
use brute force (BIG batteries) or small circuits...

The minimodular indeed... rocks.  It has a +/-15V @ 400mA supply. Its a
hungry puppy.

H^) harry

Ryan Guilfoyle wrote:

> Thanks for the ideas guys! (spec the part about
> headroom) How about this, two 9v's in series per rail
> into 7812's,that will give me the headroom for the
> regulators even if the bat's go a little flat correct?
> The only reason I'm thinking about regs is for tuning
> stability. The wasp idea is a good one too, iirc
> someone was thinking about cloning one of these with
> midi as a commercial project. The main reason for
> using batterys is for my commute to school (no outlet
> on busses)and the fact that I hate wall warts. I am
> shooting to make this thing semi-modular (ala evenfall
> minimodular, I have one and it rocks). If the 4 9v's
> and regs can do it I may just build up the madmouse
> board ive had forever and save myself some dough.
> Two more questions, how can I figure the max current 2
> 9v batts in series can give me, and does anybody know
> how much current a madmouse (the non-midi one) draws
> per rail?
>
> Once again I'm amazed at the mass of knowledge on this
> list.
>
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