New PIC project: USA_PIC :-)

Or at least throw away your brushes and use a 10" roller. :)

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.

I'm still p*ssed that $millions of my tax dollars went to buy this thing, wot anyone could make in ten minutes with a roller:

Turns out that the CIA was sponsoring abstract art as part of a cultural cold war. 8-(

Best regards, Spehro Pefhany

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The Canadian government blew YOUR money ?:-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
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           Except for those parts which are the same ;-)

On a sunny day (Mon, 16 May 2011 18:52:58 -0400) it happened Spehro Pefhany wrote in :

Right, and then this real time clock :-)

On a sunny day (Mon, 16 May 2011 20:27:13 -0400) it happened Spehro Pefhany wrote in :

Oops I though that was the new US flag after it defaulted on the debt :-)

"J.A.

Yup. My share was less than a dime, but still..

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Wouldn't you like to project a clock like that? Onto a bent surface, but flowing like Dali's work? :o)

Grant.

On a sunny day (Tue, 17 May 2011 21:11:36 +1000) it happened Grant wrote in :

Personally I am not a Dali fan, but what he tries to picture is in a way unique. I like some of the impresionists much betetr:

at least those could paint.... To put that in perspective you have to be able to darw a real diagram before you can draw a Jan Panteltje impression.

On a sunny day (Tue, 17 May 2011 21:11:36 +1000) it happened Grant wrote in :

PS I ordered some LM2596 fixed 3.3 V switch mode voltage regulators from ebay,

150 kHz, I think I can use these for higher voltages too, with an extra resistor. Will just play with those a bit, needs only a small inductor, and no other components than in - and output caps. Cheaper than from digikey, free shipping from Hongkong. 5 for less than 8 Euro, inclusive shipping.

y,

esistor.

I think it's still design overkill. I am using ST L4931CZ50-A (5V

250mA) for 97 cents and Diode Inc. AP130-33WL-7 (3.3V 300mA) for 84 cents and external switching wall plug ( 7V 1A) for $2.

On a sunny day (Tue, 17 May 2011 08:01:44 -0700 (PDT)) it happened linnix wrote in :

L4931CZ50-A is a linear regulator. AP130-33WL-7 is a linear regulator, So if your wallwart goes up to 8V (high mains), and I draw 200mA @3.3 V, then dissipation is (8 - 3.3) * .2 = .97 W

1W is already a lot for in a small plastic box like I use. Could still work if it was for an ethernet chip only, but I have several other projects, The LM2596 can do up to 3 amps, nice for bigger projects. For example that could stabilise some LEDs strings, or make a small adjustable benchtop supply.

eba=3D

a r=3D

I need 250mA @5V and 20mA @3.3V. I can use 6V (7V for safety margin) plug and

(6 - 5) * .27 + (5 - 3.3) * 0.02 =3D 0.3W.

other projects,

We design for the project, not for everything else in the future.

On a sunny day (Tue, 17 May 2011 09:13:20 -0700 (PDT)) it happened linnix wrote in :

The reason I changed the LM317 linear regulator to a switcher in ethernet_color_pic is, that even in a small box like this:

with only the ethernet (same chip) at 160 mA and a 12 V regulated switcher for supply (for the LEDs), the dissipation in the LM was about (12 - 3.3) x .16 - 1.392 W. As it had no heatsink it created a hot spot on top of the plastic box that melted something I had put on top of it, and left an impression in the box itself, of that object, permanently. That box is a WHOLE lot bigger and has ventilation openings for air, than his one: So for this smaller one I designed the LM317 switcher. I have measured current consumption at 12V as about 70 mA, that makes for 0.84 W total power into that small transparent box. The ethernet module uses .16 x 3.3 = .528 W, and some mA, say mW goes into a 7805 for the MAX232 chip. MAX232 has a typical current of 8 mA, and the 7805 a max quiescent current of 6 mA, makes (6 +8) * 5 = 70 mW Efficiency is then (.578 + .07) / 1.392 = about 47 %. Not extremely good for a switcher, but things stay cool to the touch and no melted plastic. Doing it with a linear regulator, even if I had not standardised on 12 V adaptors and connectors here, and would use a 7 V regulator, would create much more heat and melt the beautiful clear plastic housing.

So, makes me wonder how big is your box, is it plastic (thermal insulation?) or metal, and what is the surface temperature after say an hour on a 1 square meter desk without air flow? If it was metal you could mount the regulators in some way against the case, and that would likely solve the thermal problems, like this:

Then there is the US defi

V,

al =3D

_color_pic is,

..

r for supply (for the LEDs),

I don't know why you need 12V for LEDs.

t melted something I had put on top of it,

n?) or metal,

1" x 2" x 3" molded plastic.

desk without air flow?

There will be air vents.

250mA is max. worst case in charging empty battery. Average should be around 100mA.

On a sunny day (Tue, 17 May 2011 10:52:18 -0700 (PDT)) it happened linnix wrote in :

Yes, sometimes the user manual states: do to put anytything on top etc etc.

Some time ago somebody posted a chart with the surface temperatures for a wooden box of given size and given power inside it.

7 V at 250 mA makes 1.75 W... I cannot find that chart (I did download it). Some plastics melt or deform at really low temperatures.

resistor.

Good price. There is an adjustable version too. Though it's easy enough to boost a 3.3V version's output voltage.

I used some of this family devices a couple years ago for 3V regulator for A590 cam and 9V for Nikon D70 cam, running off 12V SLA battery.

Like star trail stacks:

Grant.

On a sunny day (Wed, 18 May 2011 08:31:31 +1000) it happened Grant wrote in :

resistor.

Wow, that is incredible.

On a sunny day (Tue, 17 May 2011 18:38:29 GMT) it happened Jan Panteltje wrote in :

wooden box of given size

Anyways, some of the energy will go into chemical charging in the battery, not all will generate heat. You will probably OK.