USB Power

Hey guys,
I'm sure others have already thought of this, but I think I am a bit impressed with myself...
I cut an old USB cord in half, trimmed off the data leads and am using the red and black power leads to power my axe090 hobby board. --Nice clean 5v and no more AA's!!

My USB powered Arduino board works that way too. Just don't draw too much current from it.

it's not a bad power source some of those ports can put out quite a bit, just got to be careful as some of them aren't actaully capable of putting out the whole 500ma when tested

what you're best off doing is using a powered usb hub that way you won't screw up your usb port as some of them are very difficult/costly to repair/replace

Cheap and cheerful current limiter; - put a 4.8V 300mA torch globe in series with either the red or black lead. Almost negligable resistance at low currents (picaxe 20mA) but will light up if shorted or if the circuit draws too much current. Saves potentially zapping a motherboard, doesn't need to be replaced like a fuse, is cheaper than a circuit breaker and gives a visual indication of a short.

Downloader and Power in 1 cable.

I've been using a USB-Serial adapter cable from mouser (pn 626-DLP-TTL232R) for a year now and it works great. Comes with a .01 Header for easy connection to a breadboard too. I plug it into a cheap USB hub instead of my motherboard. The USB-Serial circuit uses up 50ma leaving plenty to power my projects.

Wow, thanks guys-

I am really digging this forum -very nice people! Thank you for all your replies and, for the record, I am working off a USB hub. I like that little "fuse" trick too! I am also loving my new Picaxe!! Right now I have "borrowed" a remote control car from my boys and am in the process of hooking up all the transmitter switches to transistors. Got the first one working, only have 4 to go. Programable car, baby! The possibilities are endless!! Thanks again, folks.

could stick a gps module in that,

Dr_Acula said:

Cheap and cheerful current limiter; - put a 4.8V 300mA torch globe in series with either the red or black lead. Almost negligable resistance at low currents (picaxe 20mA) but will light up if shorted or if the circuit draws too much current. Saves potentially zapping a motherboard, doesn't need to be replaced like a fuse, is cheaper than a circuit breaker and gives a visual indication of a short.

Click to expand...

Clever idea! I'm buiding a new powered breadboard and will put one in.

Of course, in the colonies that would be a "flashlight bulb". Why "flashlight" instead of "torch"? To extend the life of the early batteries which were very expensive, peolpe would "flash" the light to illuminate the path ahead.

Myc

The USB standard only states that you can draw 100mA per port, if you need more you "should" ask for it, and the request can even be refused, meaning the item will have to stay in low power mode to be compliant.

MORA99 said:

The USB standard only states that you can draw 100mA per port, if you need more you "should" ask for it, and the request can even be refused, meaning the item will have to stay in low power mode to be compliant.

Click to expand...

certainly a good point but how does somthing like a usb charger which i doubt employs the usb data lines "ask" for more?

I'm an entrenched USB fan & have grabbed that 5V supply for all manner of tasks in recent years. It can deliver up to 500mA & overloads/shorts will NOT destroy the USB port in my experiences,but just shut it down until a PC reboot.YMMV! But although a PC will be on while PICAXE editing anyway, IMHO it doesn't make that much sense to have a $$$($) laptop on just to supply 5V for $($) finished designs!

The arrival of cheap USB socket fitted 5V plug-paks (for Ipod charging etc) makes a workaround however. These $($) 5V mains adapters are fast becoming a standard, & could make a very compact low voltage PSU "engine". That 4.8V 300mA torch globe idea of Dr.A's could even make for a simple visual ammeter,although LED designs would be more sensitive. (Stan's 2nd Law "All bench top PSU should include an ammeter")

N.B. Most 5V plug-paks are switcher based however & their output can be a tad noisy, so cap. smoothing may be needed to prevent PICAXE brain scrambling woes. Stan

Blimey, not a breadboard photo

Dippy-take your pick...

That 'birds nest' on the left is truly amazing. That it has probes attached suggests someone is seriously trying to debug it ... or it's a complete hoax and I've been suckered. Either way; great photo.

All credit to the great Bob Pease -it's not yet 1st April (although this gives me an idea for an A1 Dippy tease...). FWIW here's Bob in his pre .pdf days too.

Is that a loose connection in the centre of the breadboard?

@ Manuka : It was that bit of beard top left of the birds nest image which had me thinking it could possibly be 'for real' - Just the sort of beard a fully fledged hacker would have. Plus sandals

I hadn't heard of Robert A Pease, but a quick Googling put that right. "Passionate, talented Guru and Maverick" seems fitting praise.

That's not a beard hippy, that's one on Stan's breadboards stuck to his chin. He's been economising by using all the wiring in grey, but the giveaway is a bit of felt-tip pen marking on the 326th wire from the right.

I assume it was a high voltage and high RF design as that bloke had a full head of hair last week.