Help!

[the bus driver]

This isn't strictly a stompbox question, but here goes anyway...

Can I get a drum machine which usually works on a 9-volt ac adaptor to run off a 9 volt battery?

[The Tone God]

If the adapter is putting out 9V AC then no. Batteries are DC. Even if you could the battery probably couldn't supply enough current.

Andrew

[R.G.]

Unfortunately, probably not, or certainly not simply.

The 9Vac supply is used inside the unit to make the DC voltages that run the unit by rectifying the AC to DC, filtering it, and then regulating it down to the voltages needed. 9Vac rectified and capacitor filtered gives you about 12Vdc. This is the likely internal DC voltage that is then filtered.

You ...might... be able to find the place where the main DC is made inside the unit, hook on a battery clip, then splice 9V battery voltage there. This may or may not work, depending on how the internal power supply works. There are many, many variants of how the internal power supply could work, and some of them would not work with this kind of hacking.

Then there's the problem of power. AC powered units don't need to be particularly saving of power. They can use all the current they want. A battery powered unit can't use too much or it eats batteries. Powering a normally AC powered unit from a battery, no matter how cleverly it's done, will likely also eat batteries.

So no, there's not a simple, easy way to do this. There are complicated, expensive ways to do it that are not very practical.

[the bus driver]

hhmm, ok.

I'm new to all this stuff, I always assumed that there was ac going into the adaptor, and dc coming out, from what you've said I take it I am mistaken - ?

on the adaptor it says

ac adapter
class 2 transformer
input:230-240V ~ 50Hz
output:9V ~ 0.78 7VA

what does this mean?

This adapter seems to have stopped working so I soldered a 9 volt onto the wire. The machine lights up fine, but make a big !BUMP! noise when I turn it on and not much but a big hiss comes out when you play the loops......

[aron]

Ohhh I think you have an AC adaptor so, no, you can't easily run it off of a battery. It would probably require too much current as well.

[octafish]

Yup the sine wave on your adapter represented by the tilde~ in your post is a shorthand for AC. I think the shorthand for DC is an unbroken line with a broken line underneath sort of like pass/don't pass road markings.

[Paul Perry (Frostwave)]

on the adaptor it says
ac adapter
class 2 transformer
input:230-240V ~ 50Hz
output:9V ~ 0.78 7VA
This adapter seems to have stopped working so I soldered a 9 volt onto the wire. The machine lights up fine, but make a big !BUMP! noise when I turn it on and not much but a big hiss comes out when you play the loops......

I have some 9v AC equipment, and when upi accidentally plug 9v DC in (if the polarity is right) the digital side works (including the flashing lights) but, of course, the analog side doesn't, because the AC was intended to generate + and - rails.
What is the unit in question? it will probably be possible to confirm the power requiements on the net.

[the bus driver]

It's an Alesis SR-16 - I wanted to open it up and circuit bend it, but I heard it's not a good idea unless it runs on batteries, hence the idea...