#121

Just now realized that the 18650 is also the cell of choice for those making DIY e-bike battery packs. Pretty amazing battery. Lots of videos online about making battery packs of various sizes.

1 Like
#122

Oh, and this is what the manual says about the topic:

Does the Field Kit work on a 9V battery?
:black_small_square: The Field Kit is designed to work with a 9V power source, so a 9V
battery could be used if the user fnds a way to connect it to the
power input. The Field Kit draws approximately 80mA of current
in normal working conditions without driving any external loads,
such as an external speaker or a motor. An 8Ī© speaker driven
with full volume draws up to 220mA of current, while the DC Interface
can draw up to 500mA of current. This adds up to 800mA
of current consumption in total which would give the user with
a ā€œstandardā€ 9V alkaline battery with 550mAh capacity a usage
time of ~ 40 min in full work mode, although the voltage of the
battery would drop as it discharges. We are investigating different
ways of powering the Field Kit with a portable solution, keep
an eye on our media channels to check the progress!

Iā€™ll be getting a pre-soldered centre-negative barrel plug adapter this or next week, and Iā€™ll try it out then.

#123

Iā€™m confused because I was under the impression that a 9V battery only provides about 50mA of current.

#124

Yes, maybe itā€™s an error in the manual?

#125

According to WIkipedia (which admittedly isnā€™t always the most reliable source) an alkaline 9V battery has Typical capacity of 550mAh, which, if iirc should mean that it can deliver 550mA for one hour, after which the nominal voltage will drop below the accepted range (though I donā€™t know what that is).
If this is correct, then the manual is correct.

And btw. @vehka thanks for pointing that out. I guess I somehow remembered this part from the manualā€¦ but totally forgot that it was there.

3 Likes
#126

Battery performance is non-linear.

duracell-copper-top.jpg1644Ɨ1098 156 KB

From:

#127

Yep. so I wonder how the calculate the mAh thing, relative to what voltage?

#128

I think you mean amperage/current. So, depending on the current draw,

The Field Kit draws approximately 80mA of current
in normal working conditions without driving any external loads,
such as an external speaker or a motor. An 8Ī© speaker driven
with full volume draws up to 220mA of current, while the DC Interface
can draw up to 500mA of current.

You can look at the chart above (or get a similar chart from a data sheet for your preferred battery brand) to find expected voltage over time at that level of mA draw. You probably donā€™t want the voltage to droop far below 9V.

#129

Yes and noā€¦ and Iā€™m confused. How do they calculate the 550mAh?

#130

Chemistry and physics. Or through QA testing. Iā€™m sure the theory and praxis interact in interesting ways on the production line. I would expect the numbers to vary from manufacturer to manufacturer and from model to model.

I guess Iā€™m saying that Iā€™m far more likely to believe the battery manufacturer numbers over Komaā€™s.

#131

Some recent experiments with the Field Kit

Here the envelope from the cassette player triggers the solenoid that pushes the auto-reverse button. I love this.

This is with marbles that add variation on a PO-12 beat.

13 Likes
#132

@AlessandroBonino cool sounds! :slight_smile:

1 Like
#133

Hereā€™s another one then :smiley:

4 Likes
#134

I just received my Field Kit yesterday - not from the Kickstarter, but this seems to be merging into a general FK discussion. So far, Iā€™ve only used the on-board sound sources (LFO, radio) through the mixer and played with the DC interface for a moment. It is going to be a lot of fun for experimentation and its utility as a compact mixer makes it incredibly useful.

Any tips or tricks from the experienced users? Any wires work particularly well for the radio?

#135

For the radio i use those tighteners that come with some foods. :smiley:
They work.

The electromagnetic pickup works with motors and PSUs, donā€™t bother with modern cellphones.

2 Likes
#136

the pickup does cool sounds with old TVs, and old electronics in general (but it depends so you need to experiment with it).
As for the radio antenna, I use a standard breadboard wire. Apparently something made out of ferrite would be best though.

2 Likes
#137

Anyone hook it up to any sensors - heat, light, etc? Been curious to try this out, so I might have to do some browsing this weekend.

#138

i am curious about this as well, had a hard time finding any info/videos/examples of this.

#139

One source of info is page 31 of the manual.

#140

I ordered some cheap arduino sensors and tested them briefly. Most of the arduino sensors have 3 pins and just work. Iā€™ll write more details after Iā€™ve had more time to play with them. =)

3 Likes