I'm building the CBGitty amp and the psycho box and both use 9V batteries for power. I'm not a big fan of that, primarily because I'll need to keep running out to get some.
What about those rechargeable USB bricks? I have tons of them, big and small, around the house. But USB is 5V, not 9V, and these battery packs can put out huge current, 0.5 to 1.5A.
Can these be used safely?
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The manufacturer's spec sheet for the ARTEC amp board that Gitty sells states it will run on 5v-12v.
mines in a frame somewhere say diploma engineering ( electronic systems and computer systems ) never really got to use it..company i was working for went under before i finished it... 3 years of night school then 1 year full time.. thank god thats over....( finished back in 1988)
anyway JL's cable might work depends on the power bank you use. the RPi has the necessary circuits on board to get powered. and they assume it wont be by battery either. the trouble with USB is its a negotiated protocol. the device talks to the charger/battery bank and tell it how much current it will allow....
it all depends on how much effort you want to put in to not using a 9V battery Paul. most battery banks use 18650 lipo batteries. nominal voltage is 3.7 but at full charge they are 4.2. so you could use 2 cells get 7.4V to 8.4V . that should run the 9V circuit fine... just might have to charge the cells individually.
my problem is the boards i got are class d amps and have a 5 V to 5.5V max battery input .
I buy the little LM386 PCB's off Ebay for $2 each. I run them off throw away wall warts that are rated 5V, 9V, and 12V. They run on 5V just fine, with a dirtier output than using 9 or 12V. If you wanted to give it a try with out the bucky board.. your on the right track.,.,plenty of options...
2 thoughts: a power only usb cable that takes care of the dummy for the data wires, such as https://www.adafruit.com/product/2379
or browse your local store with RC cars, they run on rechargeable packs with a variety of voltages
Look into bucky boost transformer / circuit board - there are plenty that could raise the voltage from ~5-5.5 USB to 9V just fine.
The USB bricks put out up to 5V @ 1.5A - boosting to ~9V will mean total output about 9V @ 750mA - typical usage for 9V batteries puts the current draw closer to 30mA-50mA
And to get 1.5A out of the USB brick you will need to do something about the data lines, as this is meant for high-speed charging, the stand-by output of the USB spec is more like 500mA
I just re-read this. I missed the amperage before, jumping from 50mA to 750mA (or ever 1.5A) could make things nice and sparky...
Adding further to my previous comment -
The components i bought to test out the smokey amplifier circuit actually had voltage limits up to 30V. I was breadboarding it to use as a preamplifier in a 200 Watt Amp I am still working on, powered directly from the +12V rail of an old PC power supply - plenty of amps flowing through the entire thing but as long as the voltage is within spec you are OK.
versus when I was testing before with one of the 5V amplifier boards and mistakenly connected it to +12V ... The happy smoke was very quickly let out of the main IC...
that is not how this works, that is not how any of this works...
The circuit will only draw so much amperage.. over-voltage will fry chips and let out happy smoke, but additional amperage will just go unused...
in the case of batteries, the amperage used is partly what determines how long the battery will last on a charge - so if your USB brick is rated at 1500mAh and you draw only 50mA then it should last 30 hours or so...
but the nature of simple amplifier circuits and the psycho knob is they only draw current based on the volume of the signal passing through and the resistance of the output, so it is more likely you could rock out for a lot longer per charge than you would expect. A standard 9V battery in a basic smokey amplifier would run down quickly powering a 12" speaker cab but running a lil 4 Ohm 2" speaker could seem to last forever.
Oh that's great news! I sorta figured the amps would fry it.
This is actually really embarrassing since my diploma says "Electrical Engineering" on part of it. (The other part says "and Computer Science" and you can probably guess what part I cared more about... :- )
Its OK. It is easy to forget or confuse these things once you're out of school and really don't think about them much...
My job title is Engineer - Level 2 Support Engineer.
I have no degrees, just a certificate in Media Design and a GED.
I just know this stuff cuz its fun.
i do know a bit of Computer Science stuff too.. Not sure if I've coded more than I've soldered though.
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