Garage door IR sensor pairs are expensive (around $50 USD), and they use a proprietary communication protocol to prevent people from finding ways to disable them. It would be very difficult to use them.

I have a water pump coming from spark fun http://www.sparkfun.com/products/10455 it is 350 GPH
I am planning on attaching this to a large plastic container (tub) to make a robotic boat. I wondering if
there is any way to figure out how much weight I can put on the boat before the pump does not have
 enough power to move it.

You're going to want to take a look at http://www.homebuiltrovs.com/. They have done some testing in this area using this test stand: http://www.homebuiltrovs.com/teststand.html. We used a similar pump, but converted it to use a 30mm propeller. It moved our ~90lb ROV at roughly 1.5mph.

If I am understanding you correctly (and the specs from the XSENS website), the sensor sends its data over a serial connection, but it uses a serial to USB adapter to make it easier to connect to a computer. So wouldn't it be easier to modify the sensor so you can use the serial pins on the arduino to read it directly?

Thanks for the info. I'll look into doing that. it would be nice to be able to program it with everything attached if necessary. But as far as the basic idea of using the parts on on a larger board and programming it as an arduino, there's no problem with that correct? I guess I'm not super clear on the interface between the bootloader and the hardware. I thought the bootloader is only on the chip so as long as all the external parts (clock etc) that it needs to reference are there, it shouldn't care if there are other parts attached. As long as they don't interfere with the programming itself. I should have enough pins to leave the tx rx pins empty if I can use other pins for the serial lcd.

Thanks!

I am not familiar with the Arduino Pro mini, but it would appear that you would need a USB to serial adapter to program it using the Arduino IDE software. If I were you, I would base the board off of something easier, like the Arduino Uno. The Arduino Pro mini uses surface mount components, which are difficult to solder unless you are set up for it. You might want to take a look at the Arduino Standalone article in the playground: http://www.arduino.cc/en/Main/Standalone

So what I'm looking to do is create a custom board for my application. due to some of the components involved (serial lcd) and ease of programming I'd like to be able to interface/program it using the arduino environment. My thought is to essentially take all of the components of an arduino pro mini without changing them at all and include them with the other components I need all on one board. Is there any problem with doing that? The computer should still communicate with the board as if it were a mini and can be programmed accordingly correct?

I have heard it might be necessary to not have the serial lcd connected to the tx rx pins when uploading code to the board. Can anyone confirm that one way or the other?

You don't want the serial LCD attached to the arduino when uploading, because the serial pins are used during uploading. When you upload the code, it is possible that some of the bytes being sent over the serial lines could be recognized as commands by the LCD, which could damage it (setting the backlight to the highest value, and overtaxing the powersupply for example). You can use the Software serial library to get around this (by making a regular digital pin to a serial pin).

Hi everyone,
I was wondering if anyone has messed with a IR beam on a garage door. Im building a project and it doesnt seem that the beam is a simple high/low when it is broken. Anyone know exactly how they work.I see a DC voltage on the 2 wires but it doesnt toggle high to low or visaversa. It does change but only a small amount. I would like to use a interrupt input to detect this too.
Thansk for any help

I don't have any specifics, but I do know that garage door manufactures put quite a bit of effort into making it really difficult to disable/bypass them. I don't believe the IR sensors are simple photodiodes, they communicate with the door opener with some proprietary protocol.

I'm assuming you are "Tibo371" from Youtube, if not, just ignore my post.

I use this serial LCD from digikey, its only $21:
http://search.digikey.com/scripts/DkSearch/dksus.dll?x=16&y=16&lang=en&site=us&KeyWords=NHD-0216K3Z-NSW-BBW-ND

If you just need the extra pins for the siren and some LEDs, you can use the analog pins for that. Just treat analog pin 0 as digital pin 14.

Wouldn't you get better results if you used a cheap $50 still camera to take and store photos, and just used the Arduino to trigger it? You could use a wireless USB adapter to transmit to a "nearby computer". Although it would probably be cheaper to use a USB over ethernet adapter and 300' of cat5e.

The pros would be cost savings and space savings. You can use the Arduino to develop your project, then get an atemga 168 for $3.33, load your code on it, and only add in the parts you need for your project.

For example, this is a board I made for my airsoft props:
http://nightscapetech.com/images/stories/bombprop/thumb/Bomb_Prop_PCB_diagram.jpg
It has the same basic functionality of an arduino, but only has headers for the pins I need, and lacks a USB to serial adapter since I don't need one for my project. That board, including PCB printing costs (which you wouldn't necessarily need), connectors, and a relay, costs me about $20.

There are devices that will get you around HDCP, but they cost around $100,000 and require a lot more power than the Arduino has. Think about it, HDMI has a theoretical transfer speed of around 5GBps, thats way too much data for an Arduino to process. I'm curious as to how you are converting from the digital HDMI signal to the analog VGA signal? There is no HDCP on analog signals, so most people with this type of setup just use the analog outputs on their source device. You're not going to see a loss of quality with component over HDMI unless the environment is really noisy or the run is very long.

You're better off trying a device like this: http://www.monoprice.com/products/product.asp?c_id=101&cp_id=10114&cs_id=1011410&p_id=8126&seq=1&format=2

That device supports HDCP, according to the manual.

Depends on the type of sleep. Some computers require you to press the power button again to wake it up. This could be achieved with a simple relay on the power switch. To wake up my desktop I usually just hit the spacebar. You could either make the arduino act like a keyboard, and have it "press" a key a few times to wake it up, or you could take a cheap keyboard and have the arduino short one of the keys a few times.

A 9v battery will not damage the Arduino Mega, so long as you wire it through the internal voltage regulator:
http://arduino.cc/en/Main/ArduinoBoardMega2560

The question is, why would you want to use a 9v battery? You're going to get horrendous run time with one of those. Better off using 6x AAs.

If you can add a source of 12v, you could use some car heaters. Theres small blowers like this:
http://www.amazon.com/Wagan-EL9933-Visor-Mounted-Heater-Defroster/dp/B000BQOO6O/ref=sr_1_10?ie=UTF8&qid=1327788697&sr=8-10

110v Contact heaters like this:
http://www.amazon.com/Kats-1153-Handi-Heat-Magnetic-Heater/dp/B000BOABS6/ref=sr_1_29?ie=UTF8&qid=1327788722&sr=8-29

And 110v heating pads like this:
http://www.amazon.com/Kats-24150-Watt-Universal-Heater/dp/B000I8TQD6/ref=pd_rhf_se_shvl5

A simple transistor and relay would let you control this with the arduino if you had to. i don't know what your setup looks like, but the 12v heater would probably be the best at keeping dew off it.

I use a siren similar to this one: http://www.ebay.com/itm/NOS-Security-Alarm-System-Siren-Horn-12V-20W-1-Tone-/200597012231#ht_1631wt_1037

12v, 20W siren, so you need a 2A relay. They run fine off 9v as well. The volume is about the same as sticking your head inside a police siren.

Hi there.

I am developing an Arduino based control system for a glider launching system.

I'm about 99.9% complete and I only need to deal with the line recovery phase.

Basically, once the glider has done with the towing session, there is up to 3000ft of tow line to be reeled back onto the winch drum.

I'm looking for a way of detecting when the end of the line is near. (The line has a drogue on it to offer some resitance during the line recovery)

I was thinking of using an RFID capsule embedded in the line. As the RFID capsule passes the RFID reader I can detect it and shut the winch down.

Question is this: What is the response time for an RFID reader as a capsule is placed near it. It has to be quick and I suspect it will be ouside the 200ms range I need

Nigel

If response time is a problem, you could just mount the RFID reader farther away from the spool, on an arm or something. However, i don't think the RFID reader will have time to register that the tag is near it, if its moving that fast.

We have a hose reel that uses a styrofoam ball about 16" from the end of the hose, and a limit switch to shut the thing down. You could have a spring mechanism in the styrofoam that gives a little when it hits the switch, or you could just let the styrofoam slide on the string, and have a sensitive limit switch.

I assume weight is an issue here, so the styrofoam may be too heavy. What is the line made out of? An optical sensor may work if you paint the last foot of line bright red or something.