Auto turn-off for DC/DC converter

No offense intended Jan--your stuff is great, fun, and it's great that you share it. We all admire that. And, hand-drawn schematics are art, elegant, functional art, a window into the designer's soul. It's just that those photo'd diagrams are /really/ hard to read--the camera does not begin to do them justice. (Is that any way to treat a Rembrandt?)

-- Cheers, James Arthur

On a sunny day (Sun, 6 Feb 2011 07:46:42 -0800 (PST)) it happened snipped-for-privacy@yahoo.com wrote in :

hehe Yes, those pieces of paper is what I use to build the thing on, to protect the desktop. And it serves as a memory if I later want to change anything, For a couple of thousand Euros I will sell you an original if you like them so much :-) But I can assure the Canon camera is really good, that is EXACTLY what the original looks like. A scanner gives the same image, but is much slower. On some I actually recoded to a lower resolution jpg, should make it less readable. The other thing is that it is for people to get a clue, and then design their own, it is not a kit and I do not sell [the] parts. Those who cannot find a clue should go to ..basics. I do not think Joerg even HAS a camera, he probably uses a shoe box with a hole in it. :-)

hint hint: there are Wacom Bamboo Tablets that sell for under 100$...

z

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That's pretty neat Jan. Swing it around over your head (axis of rotation towards the center of the earth), with some sort of air-foil to keep the leds oriented properly. All sorts of advertising uses.

Georg H.

On a sunny day (Sun, 6 Feb 2011 09:59:36 -0800 (PST)) it happened George Herold wrote in :

You can put it behind a window in the car, all pedestrians will read the message, It allows you put put a new text in it via RS232, stored in EEPROM. I have made a little box for it.

The goal is to show off, not share.

Jan is not interested in shareing his desings, he just want to say "Na, na, na, I have it and you all do not".

Thanks Jan.

hamilton

they make AVRs that'll run at 0.7V I think they make low voltage pics too.

on the other hand can you hve the ON button bypass the pic's control of the regulator?

So I came up with a simple RC

Put a 1M resistor in parallel with the LED. you'll have to wait a while.

10K parallel with the led and a small signal shottky diode parallel with the 10M (anode to ground) would speed that up.

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The chip is designed so that you never have to cut the coil power. Cut the power to the SHDN pin. Since you have a SPDT, you can connect the pole to the cap, one throw to OUT, and another throw to SHDN.

You could also boost efficiency a lot by taking the FB pin out of fixed

5V mode. Get rid of the resistor between OUT and the LED. Put a resistor between the LED and ground that will have around 0.2V to 0.3V when the LED is operating at normal current. Now add a pot where the wiper goes to FB, the high side goes to the point were the resistor and LED meet, and the low side goes to OUT. That will operate the regulator with just enough current feedback to be stable. You'll be losing 0.3V * I watts rather than 1.8V * I watts.

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