USB power supply for pedals

[Dimitree]

Hello everybody
I'd like to use an external battery/portable charger (those used to charge the smartphone) on my stompboxes.
Did anyone already do that?
Those batteries output 5V, so I need to boost them to 9V.
I need to use a DC-DC converter then, do you have suggestions about which chip/design could be well suited? I could use a LT1054 but I think it won't supply enough current, I think a inductor-based design would be better. I can solder tiny SMD chips and parts, so no problems there.

[Brisance]

crude way would be to have it charge 2 cells to 5v in parallel and drain them in series.

[Dimitree]

it would not be really handy, I would need to previously charge both cells (instead of only 1) and then bring with me both..

[italianguy63]

You might have one (5V) try driving a DC/DC "buck converter"-- you can get them for less than $2 from China.  Dial on "up" to 9V..  Cool item.

(I use them to convert 12VDC down to 5VDC to run USB/Cellphones/Garmin/LED lighting in my cars....)

MC

[Brisance]

in parallel

As in have a switch which switches between "charge" and "use"

[Transmogrifox]

crude way would be to have it charge 2 cells to 5v in parallel and drain them in series.

That is otherwise known as a "charge pump".

I brewed up a simple boost converter based on discrete components for doing 12V to 330V for a tube stompbox.  I made a modified version to do 12V to 25V to regulate series heaters, which showed the circuit's versatility.

It's just an inductor value change and regulation (feedback network) adjustment for 5V to 9V boost converter.  I'm letting a simulation run in LTSpice as I type this.  Some minor component changes seem to be all that is needed to make the basic concept work.  If you're interested I can make an updated schematic to post later.  Just a handful of basic components -- no need for special transistors, special IC -- only the little inductor is "special".

[duck_arse]

the suspense is too much! what is special about the inductor?

[ben.there]

Hello everybody
I'd like to use an external battery/portable charger (those used to charge the smartphone) on my stompboxes.
Did anyone already do that?
Those batteries output 5V, so I need to boost them to 9V.
I need to use a DC-DC converter then, do you have suggestions about which chip/design could be well suited? I could use a LT1054 but I think it won't supply enough current, I think a inductor-based design would be better. I can solder tiny SMD chips and parts, so no problems there.

There are available portable power banks like you describe that have 9v outputs.  I know that Anker has a few models with 9v 2A ports.