SP900NC Webcam

I purchased a Phillips SP900NC webcam on ebay for $50.00 with the idea of modifying it for long exposure. These modifications have been published on many websites. These modifications are controlled by a computer parallel port which is now impossible to find on a laptop. I took an very old (obsolete) motherboard that has a parallel port built in and put it into a box that I built with a power supply to control this camera. I call this my dirt-top computer (laptop … dirt-top, never mind..). Used a large 12V battery running an inverter to power the computer. All this is very cumbersome. There is a modification that works over USB only out there that I would like to try (see below). I only did the long exposure part of the mod – thinking I would do the amp off mod later. Ended up doing the USB mod shown at the bottom of this page.

The software to control the camera is called wxAstroCapture – it is a free program that has a long exposure function. Without the amp off mod the longest exposure I could do was about 10 – 15 seconds. The program creates a .avi file that can then be processed by RegiStax which is a free image processing software that stacks the individual frames of the .avi file. The image can then be post processed using PhotoShop or other image manipulation program.

I used the camera with my 8″ Orion reflector on the Orion Sky View Pro equatorial mount. Focusing the camera on an object the first time was really difficult.  The field of view is tiny (about 1/4 degree)  and just touching the focuser could move the object off of the chip.

Some early results:

I finally decided to convert the camera from parallel port control to usb control. First I had to undo the parallel port modifications shown above. I soldered tiny jumpers to repair the cuts I had made on the board. The new modification required cutting pins 7 & 9 on the connector between the two boards, I figured that This mod could be corrected with additional jumpers if it didn’t work.  I got the wiring diagram for the modifications from this website: http://www.yesyes.info/index.php/diy/philips-spc900-webcam-lx-and-ampoff-mod/

Thanks to yesyes DIY and astro for making this information available. On the wiring diagram photo the pins and the solder pads appear to be off – I believe this is due to the camera being angled with respect to the board when the picture was taken. The diagram is correct: the pins to break are 7&9  and the pads to solder to are 7&9. I took some pictures during the modification process.

I saw no need to try to get the usb to serial converter or the usb splitter into the case. The control signals are brought in through a 9 pin D connector. and the video cable is brought out through a grommet in the case.

Downloaded wxAstroCapture http://arnholm.org/astro/software/wxAstroCapture/ to my laptop. Installed the driver that came with the prolific usb to serial converter, set up the com port in wxAstroCapture and set the frames per second to 5. My camera sees light and color. The long exposure and amp off modifications appears to work!. Next step: put it in a telescope. I will post some pics soon (weather permitting).

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