Show Posts
Pages: 1 ... 330 331 [332] 333 334 ... 452
4966  Forum 2005-2010 (read only) / Development / Re: Whats a good PIC programmer (hardware). Epic? on: July 07, 2009, 03:20:35 pm
2nd the recommendation for PICkit2...
4967  Forum 2005-2010 (read only) / Development / Re: Amanduino - final design on: June 24, 2009, 05:30:24 am
Check the USB-mini connector pinout; you have a different pin connected to GND than I do on the Freeduino design that has an SMT mini-USB connector.  But I'm not sure which is right...
4968  Forum 2005-2010 (read only) / Development / Re: Voltage regulator suggestions? on: June 10, 2009, 03:38:23 pm
You should be able to find or build a 12V-5V switching regulator for much less than $15.

1) Check thrift stores for car phone chargers.  A lot of these are 12V to (approximately) 5V switching regulators.  Or you might find a 12V to 8V regulator which would power the input to a 5V linear regulator for a nice overall efficiency boost.  Most of these are based on the mc34063 switchmode chip, which is less than $1 (for just the chip.)  So  you can consider building your own.  (or import modules from china: ?)

2) Consider discreet circuits like  "The Black Regulator"
    Somewhere I have a freeduino board design with a Black Regulator replacing the linear, but I've never built or tested it (nor even a plain Black Regulator), so it's "not ready for prime time."  It does fit, more or less.

60% is really poor for a switchmode converter, BTW.  Most are 80% plus...

But the efficiency difference IS pretty dramatic.  Back in the good old days, large computers had these HUGH linear power supplies.   One mainframe I was familiar with, during its decline into dotage, had someone do a mod where "modern switching power supplies" were added to replace the linear monsters.  The supplies were small enough to fit in the chassis without removing the old supplies, and the increased efficiency allowed the mod to pay for itself VERY quickly, once you took into account both less power into the computer AND less power used by the air conditioning...
4969  Forum 2005-2010 (read only) / Development / Re: Voltage regulator suggestions? on: June 09, 2009, 02:21:39 pm
The power consumed/dissipated by a linear regulator is:
     Preg = (Iquiesenct * Vin) + ((Vin - Vout) * Iload)

And of course the power consumed by the load is:
    Pload = Vout * Iload

"Efficiency" is then:
    E = Pload / (Pload + Preg)

A simple regulator like a 7805 has Iq of a couple milliamps, which is absolutely terrible if you have a microprocessor that spends a lot of its time in low-power modes consuming fractions of a milliamp; you'd like the circuit to be nearly OFF under such circumstances, and there it is still consuming several mA.
But for an operating circuit consuming some 10s of mA (an arduino is "about 50mA"), the dominating factor is that ((Vin - Vout) * Iload) term, and that's NOT dependent on any characteristic of the regulator itself; it's pure physics ("ye canna break the laws of physics!")
A low-dropout regulator will permit you to use a lower Vin to increase efficiency, but that's frequently a factor not under your control (batteries coming in fixed voltages), so they frequently don't help much in the real world.
4970  Forum 2005-2010 (read only) / Development / Re: new arduino with Xmega avr serie on: June 17, 2009, 04:50:56 pm
The xMegas, while announced in Feb 2008, have only appeared at distributors within the last couple of months (and only SOME of the announced parts.)  HW designers are being ... cautious.

There have been previous discussions; it's also not clear how many of the xMega features would "fit" within the Arduino environment.   Faster clock and more RAM is nice, but DMA is ... hard to simplify.

I was a bit annoyed to see that the 100pin xMega chips are not at all compatible with the 100pin Mega chips.  It would have been nice to plop an xMega onto the MEGA board and double the clock speed/etc, but it can't be done :-(
4971  Forum 2005-2010 (read only) / Development / Re: eagle libraries on: June 18, 2009, 02:00:47 pm
EXPORT is in the FILE menu.
4972  Forum 2005-2010 (read only) / Development / Re: eagle libraries on: June 17, 2009, 07:40:13 pm
(if you BOUGHT 4.09, then 5.6 might be an expensive upgrade...)
4973  Forum 2005-2010 (read only) / Development / Re: eagle libraries on: June 17, 2009, 11:26:26 am
Get the EAGLE freeware version of 5.6, load the desired libraries, EXPORT them as a script, and see if you can read the script in your 4.09 version  (you may have to do some text editing of the script, but perhaps not.)  Don't let 5.09 overwrite the eagle.ini files (I think it will ask...)
4974  Forum 2005-2010 (read only) / Development / Re: CompuBlino Arduino based computer bling on: June 15, 2009, 01:42:14 am
It still has a voltage regulator of unlikely usefulness...
4975  Forum 2005-2010 (read only) / Development / Re: CompuBlino Arduino based computer bling on: June 13, 2009, 01:30:36 am
Why bother having a 5V regulator when your computer has a whopping huge 5V capability already?
(actually, it looks like you're trying to run the 5V computer supply through a 5V regulator as well, which won't work...)
(however, a fuse of some kind might be a good idea!)
4976  Forum 2005-2010 (read only) / Development / Re: Arduino Mini  Footprint for Eagle on: January 16, 2008, 10:54:03 pm
I could probably make one pretty quick, but I wouldn't be able to test it...
Come to think of it, a set of footprints for ALL the arduino boards might be useful; the footprint for the "standard" arduino would pretty much be the "shield prototype" that other people have been asking for.
4977  Forum 2005-2010 (read only) / Development / Re: ATmega328 vs ATmega128 on: June 03, 2009, 01:37:47 am
Note that you can go the other way too, plugging an ATmega8 into the same socket that had your 328 once you decide the code and features are sufficient (for some reason, ATmega8's seem to be especially inexpensive  purchased from eBay.  Hopefully they're not counterfeit...)
4978  Forum 2005-2010 (read only) / Development / Re: 1337uino MINI (alpha) need endorsed... on: May 09, 2009, 11:34:04 pm
There is now a higher-res PDF file here:

It's "printed" on A3-sized paper (big), so you can zoom in quite a lot to see details.
4979  Forum 2005-2010 (read only) / Development / Re: 1337uino MINI (alpha) need endorsed... on: May 08, 2009, 06:55:36 pm
Even the largest size available on flickr is unreadable...
An actual .sch file put somewhere would be a lot better.

Hate the name. :-)
4980  Forum 2005-2010 (read only) / Development / Re: A Cheep Easy Ethernet Shield on: May 06, 2009, 11:33:08 pm
The wiznet chip isn't inherently that much more expensive than the Microchip ethernet controller, and the Wiznet chip does a lot more for you.  If you can figure out how to bypass the relatively expensive manufacturing costs, you could produce a clone of the official shield and maintain SW compatibility.  (This is one of the big advantages of open source; if you need large quantities of cheap, you can figure out how to make it yourself.)
(For that matter, you might be able to design a home-builldable PCB that uses the Wiznet 811MH MODULE (less than $20) and get something SW compatible for about half the price of the official shield.)

Unfortunately, ethernet for microcontrollers hasn't really hit the "economies of scale" that would make it cheaper....
Pages: 1 ... 330 331 [332] 333 334 ... 452