Thanks for the excellent tips.

The rotary solenoid sounds perfect.

>   I would use a rubber hose or a rubber foot (the kind with a hole in the middle for the screw) to "grab" the camera knob.

Interesting. Could you elaborate on this? I've been worried about damaging the knob through excessive force, and this sounds like a good solution.

As far as the camera being controllable via USB, this camera's predecessor, the S3, turns on when it receives 5v through the USB port. Alas, for whatever reason, the S5 doesn't do that, but I need to use the S5 because only it has a flash hotshoe.

Interesting. Can I make a servo motor turn both ways? After it turns that dial, it needs to then turn it back the other way.

I have a servo motor, but it only has 3 wires, which as I understand it is two power leads and one signal lead.

Looking here for example:

http://itp.nyu.edu/physcomp/Labs/Servo

I'm trying to remotely turn on a Canon Powershot S5 camera. It has a power knob that you turn about 15 degrees and then it snaps back to center. Here's a picture:

http://www.digitalcamerainfo.com/images/upload/Image/Canon%20S5%20IS/Product%20Photos/S5IS-top.jpg

Note that knob at the bottom right, with the "off" button inside of it. I'd like to simply turn that knob.

I was thinking a stepper motor glued to the top of the knob?

That's kind of a shot in the dark though, I have no experience with stepper motors. If I went that route, would I then use something like this to drive it?

http://store.fungizmos.com/index.php?main_page=product_info&products_id=246&zenid=e9a645bf0b7067566c3ba2aa58502443

And any tips on which motor to use?

Or maybe I'm barking up the wrong tree?

Thanks for any help.

I found this circuit, which looks pretty perfect:

http://www.electronic-circuits-diagrams.com/alarmsimages/6.gif

More description here:

http://www.electronic-circuits-diagrams.com/alarmsimages/alarmsckt6.shtml

One thing I'm not sure about is how to connect this to an Arduino. Could I just connect to digital inputs instead of the LEDs?

I need my Arduino to measure the water level in a 50 gallon drum. I don't need very fine resolution, in fact I really only need to know when the drum is almost empty.

I found a few posts that recommend doing this by measuring pressure in a column of air or water, such as this blog post:

http://spiffie.org/electronics/archives/microcontrollers/Arduino%20and%20Freescale%20MPX%20Pressure%20sensors.html

And I could dfo it by measuring the weight of the drum. But for my purposes I was hoping for an even simpler solution, and one that would allow me to mount the Arduino 10 meters or so from the water barrel.

I used to have an RV that measured the level in its water tank via a sensor placed in the water itself. All the sensor did was know if there was water at that point. Note that it could distinguish between it being a little wet and actually submerged. Can anyone think of a way to do this?

Thanks for any help.

For future reference, I just discovered that the Arduino IDE can monitor the arduino just fine. Click the serial port button at the top right of the IDE....

I wrapped a gui around it:

http://gizmoware.net/arduinospy/ArduinoSpy.exe

For now its Windows only, but its Python so once I get the kinks out I'll cross-compile. Still definitely beta. For example I'd like to change the way the serial port is getting polled to make it a bit more efficient. I'll release the Python sourcecode once I finish it. No clue whether it works on Vista, feedback invited.

A few features:

- not meant to be a general purpose arduino/computer bridge like gobetwino, this is just to see println messages from the Arduino for debugging.

- single file, no installer. Sorry about the file size, the program itself is very small but I have to include all the Python libraries.

- minimal interface, and resizable and remembers window size & position.

- global hotkey: printscreen or scrolllock will connect/disconnect from the arduino. So if you need to upload a new version of your script to the arduino, hit printscreen to disconnect without having to focus on arduinospy.

- can optionally try to find your arduino

- if you need to go to device manager to look up your arduino's comport number, view --> show device manager

- button turns green when connected, red when not. The idea is you can see connection state at a glance

True, but personally I see a commandline switch as a hassle since that means not being able to run it with a mouse click. I suppose someone could make a shortcut with the switch included or a batch file, but still that's extra work.

Something like this might be easier:

Code:

comport = raw_input("What's the number of your com port? ")

Or better yet just hard code the comport number in the script and have the user edit the script manually, since the comport number probably won't change on any given computer:

Code:

comport = 6

If I get a chance I'll wrap it in a simple gui using WxPython, my gui framework of choice. I'm not sure how much need there is for one though since gobetwino works.

Thanks, the gobetwino works. I made a little Python script that works too if anyone needs it:

Code:

import time, wmi, serial

def find_arduino():

    c = wmi.WMI ()
    for device in c.Win32_PnPEntity ():

        current = device.Name

        if "(com" in current.lower():

            if "FTDI" in device.Manufacturer:
                # figure out the port # with a horrible bit of duct tape
                # other way to get the port number?
                comport = device.Caption.replace("USB Serial Port (COM", "")
                comport = comport.replace(")", "")

                try: comport = int(comport)
                except ValueError: return None

                return comport



print "Searching for the arduino, this might take a moment..."

comport = find_arduino()

else: comport = 6

if comport: print "Hallelujia, I found it! Its at COM" + str(comport) + "..."
else: print "Whoops, I didn't find an arduino..."



baud = 9600
ser = serial.Serial(comport - 1, baud, timeout=.25)

while True:    
    ln = ser.readline()
    ln = ln.replace("\n", "") # get rid of the extra hard return
    print ln
  

Note that this is written for Windows. The only semi slick thing it does is find the Arduino's serial port automatically, at least on my computer. It does this using the Windows WMI interface using a bit of duct tape. Its slow since it iterates through the entire PNP interface, but it works reliably for me.

Would probably be better to hardcode the serial port if you're running it often.

And also note that you'll need to install the pyserial module from here: http://pyserial.wiki.sourceforge.net/pySerial

And I think to use WMI you need to install the Windows extensions for Python.

I'm wondering if its possible for the computer to receive messages from the arduino? In other words, have the arduino print the word "hello" or whatever, and have it show up on the computer?

I'm guessing if so it's using the Serial class, but I'm not sure how to receive the messages. I'm on Windows if it matters.

Thanks for any help.

D'oh! Didn't know the IDE had that feature. Very very handy. Oh well, it still passed the time at the airport, and was good practice for me doing guis in wxPython from scratch.

But no I'm not giong to add interactions with the computer from this, gobetwino already exists for people who don't program, and for people who do its way easier to just script something in Python or whatever.

I suppose I could add support for Arduinos to another program I wrote called Control Freak, which lets you control a bunch of things on the computer from a variety of sources, and Arduinos would be easy enough to add.

http://gizmoware.net/controlfreak

By the way if anyone needs some code to interface an Arduino with Python, I'm sure there's lots of examples around, but here's the code that's the core of ArduinoSpy:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238637191/

I made a little program to interface an Arduino to Windows and soon Mac and Linux:

http://gizmoware.net/arduinospy/

I needed something to get traces from my Arduino programs and had a long airport layover... Note that Gobetwino will show output from an Arduino too, but for me ArduinoSpy is a bit simpler for just getting debug messages. And plus variety is a good thing. Some notes:

- written in Python so once I get the kinks out I'll release it for Linux and Mac along with sourcecode

- minimal interface, and resizable and remembers window size & position.

- single file, no installer or registry involvement. Sorry about the file size (8 megs), the program itself is tiny but I have to include all the Python libraries.

- global hotkey: printscreen or scrolllock will connect/disconnect from the arduino. So if you need to upload a new version of your script to the arduino, hit printscreen to disconnect without having to focus on arduinospy.

- can automatically detect your arduino

- if you need to go to device manager to look up your arduino's comport number, view --> show device manager

- button turns green when connected, red when not, so you can see at a glance whether you're connected to an arduino.

This is most definitely a beta, and I haven't tested on the dreaded Vista. Feel free to let me know how it works or doesn't work for you or if you need it to do something it currently can't.

wrybread at gmail dot you know what.

Wow that would be fantastic if those were 12v. In the past I've owned an LED crosswalk sign, and if I remember correctly it was wired for 48v, which is brutal to work with for me.

Does your have any brand markings on it?

And did you have to physically open the sealed light fixture?

Would there be a way to dim these guys?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150332729949&ssPageName=ADME:B:ONA:US:1123

I'm guessing this would be much too slow:

http://cubloc.com/product/01_03ssr4.php