After putting off working on this project for a bit, I’ve taken in up again this week and successfully used the bluetooth chips to send data between two computers. I set up one of the chips on my server (using a RS-232 adapter board), and used my D-Link DBT-120 bluetooth adapter on my desktop. Using hyperterminal, I was able to send ASCII characters and small files between the two machines without too much trouble. One of the issues I noticed is the inability of the two bluetooth devices to reestablish a connection when one of them is turned off. I think the problem lies with the settings on the ACODE-300 bluetooth chip that I’m using but I am not sure. I need to do more testing, but I’m pleased with the success of the chips so far.
After getting the bluetooth to work between two computers, the next logical step was to test it with the microcontroller that will eventually be placed in the car. I was unable to get the microcontroller to communicate wirelessly. The only reason for this that I can think of is the serial cable may need to be a crossover cable. I have a crossover adapter, but I can’t connect it until I get a male to male gender bender. I’ll probably run down to Radio Shack (they’re not big on carrying useful stuff anymore…) tomorrow to try get one so I can get this thing going.
In researching information about using a webcam as a low cost camera for astrophotography, many people recommended the Philips SPC900NC camera due to its use of a good quality 1.3 megapixel CCD sensor at a decent price. I bought mine from ebay, but its also available on Amazon and Newegg. My first attempt at playing with this camera was on my main desktop running Windows XP x64. This proved useless, however, as the drivers will not work. The Philips software will install fine but it cannot recognize the camera. Windows detects that a USB device is plugged in but can’t do anything with it because of the incompatible driver. I currently do not have a 32 bit version of Windows XP, so the next course of action was obviously Linux.
My laptop currently runs Ubuntu (was running Xubuntu until yesterday, just did a little swap of GUI’s) and was a prime choice. The camera did not work “out-of-the-box” as can be expected, but a little searching netted me a working driver for the camera, known as pwc. The pwc driver works for many Philips cameras, including the SPC900NC that I’m using. Installation is very straightforward for anyone who has compiled programs. Once the driver was installed, Camorama didn’t have a problem detecting the camera and capturing images from it. Next step is to work on capturing video from the camera, which mplayer may do for me.
Since the camera is working, I took a few pictures to test it out. Image quality is pretty good and should work perfectly for my astrophotography plans. Here is a picture of my Tele Vue Pronto refractor that I’ll be using for this project:
A while back one of my roommates bought 2 LED displays as part of a project idea. The signs kind of fell on the backburner as other things came up, but I thought that I could start playing with one of them since it shouldn’t need much work to get it operational again. The display is an Alpha 210A, and is missing both its power supply and controller. Normally a missing power supply wouldn’t be a problem, however this sign uses 7.5VAC. Finding a transformer with a secondary rating of 7.5VAC proved to be rather difficult, but I finally managed to find a place that had something usable. Herbach & Rademan carry a transformer that provides 7.5VAC at 1.5 amps, so I need 2 of them, as the sign is rated at 2 amps, but for $3.95 a piece I can’t complain. They do have a $15 minimum order but they had other items that I needed anyway. Their site does not have a secure checkout, so you might want to consider calling or faxing your order.
The next issue, of course, is the programming controller. According to the Alpha website, the displays use either RS-232 or RS-485 to communicate with the controller. I’m not sure which standard my sign uses, but if its RS-232 conectivity will be easy. RS-485 shouldn’t be a problem but will require an adapter. I’ll look for the specifics of the communications once the transformers come in and I can verify that the sign actually works.
An article in the December 2006 issue of Astronomy magazine about using cheap webcams for astrophotography got me quite interested. After doing some research this evening, it seems like it can be a cheap and fun project to undertake. I think I have my heart set on a Philips SPC900NC webcam, which goes for about $50-$70 on ebay. It would require a telescope adapter which goes for $20 shipped on ebay. My plan is to use this webcam and experiment much more fully with astrophotography than my past musings, which consisted mostly of taking an occasional film photograph of the moon or other easy targets. By shifting to a digital medium, I’ll be able to experiment a lot more without the guess work of traditional film, plus the webcam is cheap compared to specialty cameras.
My first target will most likely be the moon, as its easy and provides a good starting point to developing the techniques, starting with single pictures, and then moving on to mosaics. Images are captured by taking an AVI video for a length of time, using software to turn the AVI into a series of stacked images, and then combining the stack to reduce noise and provide a much clearer image. I’ll be able to provide more details once I get going with the project, but two popular programs used for this kind of photography are K3CCD ($49.00 after 35 day free trial), and RegiStax (free!). I hope to use my dad’s 8″ Schmidt-Cassegrain telescope for most of the images, however I’ll probably have to use something a bit smaller (like a Tele Vue 76) most of the time. This might have to turn into a spring project to take advantage of warmer weather…