Li-Po power supply for active pickups.

[RobA]

Well, it's not a pedal, but I'm happy with it, so here's a report anyway.

I've been working on this for some time now and I'm finally really happy with the results. This is a circuit I built to take the input from a Li-Po battery and outputs 9.6V of really clean power. Actually, according to my measurements, the output power is cleaner than a straight 9V battery. The other main advantage is that the power sits at 9.6V for the entire life of the charge -- and the charge lasts months.

The photo below is of the battery and the boost installed in my Kramer "American" Forum II bass. The bass has active SD pickups in it and active electronics (bass & treble TC). (The "American" is in quotes because according to every thin I can find, the bass was made in Japan.) I've got the Li-Po circuit installed with EMG and Active Blackouts as well.

The boost PCB is sitting on the original battery clip tray and clipped in using a battery snap. The only other connection to the bass is an additional ground wire.

Note that in the photo the charge port isn't connected. I haven't decided yet if I should just drill the mounting hole in the bass' cover plate or not. I can't find any good info yet on if the bass actually has any value or not. I'm guessing no, but if it does, I'll cut a new plate out of plastic to keep the original intact.

 

[jkokura]

Rob, I'm very interested in putting this sort of thing in one of my acoustic guitars that runs a Fishman Matrix 2 preamp.

I wonder if you could get it into a package that's very similar in size/shape to a 9V battery, or at least some sort of package that mounts easily into something.

Jacob

[sturgeo]

Very ballsy using a LiPo in a guitar, my brother uses them in his RC Cars and they can be very volatile!

[jubal81]

Very ballsy using a LiPo in a guitar, my brother uses them in his RC Cars and they can be very volatile!

I believe the Li-po is the safer chemistry among lithium batteries.


Really great project, RobA! I especially like that the voltage is stable throughout the life of the battery. Any chance you'd be willing to show the schematic?

[muddyfox]

i've dabbled in rc racing for quite a while and the only time i've seen a violent lipo reaction when the battery was either charged or discharged at very high current, none of which i see happening here. yeah, i'd stick a lipo in a guitar ...

[RobA]

Rob, I'm very interested in putting this sort of thing in one of my acoustic guitars that runs a Fishman Matrix 2 preamp.

I wonder if you could get it into a package that's very similar in size/shape to a 9V battery, or at least some sort of package that mounts easily into something.

Jacob

I'm working on a version for an acoustic setup now. It'll be a bit different though, since I'll be doing it with a split rail design at +/-5V. It will let me test how this works with a couple of different types of acoustic pickups.

Getting it into a 9V battery compartment is doable. I had one packed into the 9V slot on my EMG equipped Charvel. It was tight, but doable. The only problem there is that you have to go with a smaller battery in the type I've been using. The battery in the pic is a 1000mAh. The one that I used that would fit in the compartment is a 450mAh. That'll still last months in the testing I've done so far. The other possible issue is that you have to get a ground wire out that goes from the boost to the ground in the guitar.

Very ballsy using a LiPo in a guitar, my brother uses them in his RC Cars and they can be very volatile!

I believe the Li-po is the safer chemistry among lithium batteries.

Really great project, RobA! I especially like that the voltage is stable throughout the life of the battery. Any chance you'd be willing to show the schematic?

The Li-Po is a pretty safe battery. You can cause problems with them if you puncture them. You've got to be careful charging them too, but I've got a companion circuit to this that is a charger for it and you can set the charge rate to match the battery size you use.

Yeah, I will almost certainly put out the schematic for this and the charger. I may actually decide to try to commercialize this in some way, but even then I'll do it as an open hardware project. I want to do just a bit more testing with it though before I do. I've only had the latest revision in the guitar for about a week. It's only a minor change from the last one that's been working for a couple of months, but I'd like to verify it for just a bit longer.

[alanp]

Niiiice, I wonder how well this would sell.

[mario741]

Hi!

I can't see the photo, how was the circuit?