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241  Using Arduino / General Electronics / Re: Controlling ATX power on switch with 3.3V Arduino on: September 03, 2013, 08:42:20 am
http://pewa.panasonic.com/assets/pcsd/catalog/tx-s-catalog.pdf
It requires 16 mA at 3V.
242  Using Arduino / General Electronics / Re: Controlling ATX power on switch with 3.3V Arduino on: September 03, 2013, 06:13:00 am
A reed relay would also work.
243  Using Arduino / General Electronics / Re: Voltage regulator and battery pack on: September 03, 2013, 06:10:37 am
The sentence I quoted was from the first page, right side (STANDARD APPLICATION subtitle).
You can also find the information in multiple tables (characteristic is called "Dropout Voltage").

You could use a standard 3,3V regulator if that is the version you have (3,3V Pro Mini), or a low dropout regulator, something like this:
http://www.farnell.com/datasheets/78392.pdf
It has typical dropout voltage of 0,32V.
244  Using Arduino / General Electronics / Re: Voltage regulator and battery pack on: September 03, 2013, 02:20:40 am
The datasheet says "The input voltage must remain typically 2.0 V above the output voltage even during the low point on the input ripple voltage."

Your 4 AA batteries don't supply 7V, so the voltage regulator can not function properly.
245  Using Arduino / General Electronics / Re: Controlling a solar panel via Arduino & MOSFET on digital pin on: September 02, 2013, 02:38:36 pm
What about a latching relay?
246  Using Arduino / Project Guidance / Re: Science Fair Project on: September 02, 2013, 12:44:42 am
Arduino is not good at image processing.
You'd have more chance to do it in a reasonable amount of time with a Raspberry Pi, or even a full fledged computer.
247  Using Arduino / Project Guidance / Re: Arduino as Still controller on: August 31, 2013, 01:43:12 pm
Sure you can. If all you need is one temperature sensor and one vent/motor, than any arduino will be able do that with its hands tied behind its back.
An ATtiny45 can do it too.
248  Using Arduino / Project Guidance / Re: Hyperbaric on: August 31, 2013, 06:07:23 am
OP did not mention pure oxygen.

Quote
regulate the air flow inside the unit
Quote
pushing air into a sealed vessel.
249  Using Arduino / Project Guidance / Re: Hyperbaric on: August 31, 2013, 05:21:08 am
There should not be any medical concerns regarding that overpressure. The increase in pressure is equivalent to diving three meters under the surface of water.
It's mechanical stuff that won't hold up.
250  Using Arduino / Project Guidance / Re: Hyperbaric on: August 31, 2013, 01:02:19 am
Radman, the pressure in that sort of inflatable buildings is usually around  250 Pa. That's far, far away from 30 000 Pa drfpoulin is mentioning.
The last such inflatable structure I was in was a tennis court (well there were 4 or 5 of them inside) and it had revolving doors so you didn't have to worry about releasing all that air.
The pressure differential could be felt once you enter, but certainly nothing uncomfortable. Sort of like what you feel when driving down a mountain road from higher to lower altitude.
251  Using Arduino / Project Guidance / Re: Hyperbaric on: August 30, 2013, 02:33:01 pm
That's, what, 30 000 Pa of overpressure?
So, 1,3 atmosphere. If my calculation is correct, that's around 85 000 N of force on an opening with 60 cm diameter (something a person might crawl through). I would not mess around with those forces and the thing pictured in your first post most definitely could not withstand that pressure, even if you could seal the door itself.
Controlling the pump and a release valve is doable with arduino, but not advisable for this purpose in DIY method.
252  Using Arduino / Project Guidance / Re: Hyperbaric on: August 30, 2013, 11:40:15 am
From what I could investigate, the thing in the picture is not a hyperbaric chamber at all. It's an armchair with roof, a door and a TV. That's it.
http://www.mccormackdesign.co.uk/design/ovei-pod
253  Using Arduino / Project Guidance / Re: Tiny, really tiny 7 segment display on: August 27, 2013, 03:18:22 pm
I'll have to check that out. Thanks for the tip.
254  Using Arduino / Project Guidance / Re: best way to keep arduino powered in car when car is off on: August 27, 2013, 03:17:17 pm
CrossRoads, car batteries can be as small as 50 Ah on smaller cars. "Hundreds" is a bit of an overestimate even for larger diesel engined cars.
That could be a problem if there is additional power consumption hooked to arduino.

All that being said, there is always a fuse box that is powered all the time. It is usually near the steering wheel or in the glove compartment area.
255  Using Arduino / Project Guidance / Re: Tiny, really tiny 7 segment display on: August 27, 2013, 12:45:10 pm
I need only one or perhaps two of these displays so ordering the board seems a bit of an overkill.
An OLED display would also be a bit too large, I believe (I'm talking about the entire package).

Well, I suppose I'll just get some LEDs and start experimenting.
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