Replies to This Discussion

Permalink Reply by Timothy Hunter on December 17, 2017 at 1:22am

the amp should still work at 5V but if it does it wont be as loud and may be distorted even on clean settings. depends on how the amp was designed.

USB power bricks might not output any voltage when powering an amp. i will try to explain. I tried 2 different USB phone power banks. I was trying to power a 3W class D amp board I bought off ebay. seemed like a good thing as the amp board was 5V. So i grabbed a spare USB cable cut it and hooked the black and red (gnd and +5V) the white and green are the data lines. ... and nothing.. tried it on my phone and it charged... hooked the amp up...nothing..

The battery bank needs to see some resistance between the data lines to enable it i could not find out online what it should be and gave up. 

• ▶ Reply

Permalink Reply by Paul Cezanne on December 17, 2017 at 3:36am

Bummer, but I guess I should have expected that. I just found a few more amp kits online, and they still all use 9V.

mmm, maybe I can put two in series, get 10V, fake out the data lines...

• ▶ Reply

Permalink Reply by Korrigan on December 17, 2017 at 4:45am

Unless you really need the devices to be portable/battery powered all the time, why not add a 9v wall adapter option for when you have access to an outlet?

• ▶ Reply

Permalink Reply by Paul Cezanne on December 17, 2017 at 2:12pm

That's a good answer. Why? Because the real question is why don't I like 9v batteries? I don't like them because I don't like batteries going in landfills.

So a good solution is both a 9V power adaptor or a set of rechargeable 9v batteries!

• ▶ Reply

Permalink Reply by Br Harold F Stubbs III on December 17, 2017 at 7:40am

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

• ▶ Reply

Permalink Reply by Paul Cezanne on December 17, 2017 at 2:11pm

Oooo, I can get my inner geek on, yeah, that could actually be fun.

• ▶ Reply

Permalink Reply by Br Harold F Stubbs III on December 17, 2017 at 2:43pm

I would be very interested in whatever you try and your results - I have a few 5 volt mono amplifier boards and a USB LiPo charger board and LiPo I haven't gotten to play with yet, as well as few of the psycho boards now. I was planning on building a rechargeable travel guitar but didn't have a complete plan yet.

The USB bricks do open up some potential to use Arduino or Raspberry Pi to create FX or control options... it will all come down very quickly to how much draw you can get and how much capacity the brick has.

btw - a basic smokey amplifier circuit will run fine just lower volume with 5V input straight up. CB Gitty themselves have indicated in a message to me that they have not tested the psycho board above 9V and don't recommend it as they just don't know what the limits really are for it.

Likely it should be fine up to ~12-15V but I wouldn't push it much past 10V without being willing to sacrifice it on the altar for everyone else to know.

• ▶ Reply

Permalink Reply by Paul Cezanne on December 18, 2017 at 12:38am

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...

• ▶ Reply

Permalink Reply by Br Harold F Stubbs III on December 18, 2017 at 7:16am

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.

• ▶ Reply

Permalink Reply by Paul Cezanne on December 18, 2017 at 1:40pm

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... :- )

• ▶ Reply

Permalink Reply by Br Harold F Stubbs III on December 18, 2017 at 2:53pm

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.

• ▶ Reply

Permalink Reply by Br Harold F Stubbs III on December 18, 2017 at 7:22am

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... 

• ▶ Reply

• ‹ Previous
• 1
• 2
• Next ›
• Page