12v L7809

[hazefuzz]

I recently bought a new pedal,

It's came with 12vdc power supply (1000mA) but on the pcb there is voltage regulator (L7809)
http://www.datasheetcatalog.com/datasheets_pdf/L/7/8/0/L7809.shtml

if I understand correctly It's 12v to 9v ........ 
so why they just didnt use 9v power supply or battery like any other stompbox

[WaveshapeIllusions]

I would assume that they want that 9V regulated. Regulators drop some voltage, so that difference of 3V is needed to do its job. The supply is most likely unregulated, so I guess they found it simpler to tell people to get a higher supply rather than specify a regulated one.


What pedal is it?

[mth5044]

Perhaps some of the circuit is powered at 12v and some at 9? Idk

[cortezthekiller]

I would think that if the pedal uses a 1 amp power adaptor that batteries would be useless and common single-pedal adaptors wouldn't hold up?

[Digital Larry]

You can free yourself (to a certain extent) from worries about ripple (hum-causing) from the wall wart by doing this.  Get a cheap wall wart then add a (fairly) cheap voltage regulator on board.

[mistahead]

Its a digital pedal I'll wager.

I've seem this commonly used to ensure a "perfectly regulated and filtered X volts" to a couple of digital multi's and the such.