Phillips Webcam Mods

[The Thing]

Hi all,

Finally got my Phillips SPC900NC to do long exposures, it also has a BW chip for greater sensitivity and has been rehoused with a fan added on the end of the enclosure for good measure.

I used M Meijer's instructions at http://home.zonnet.nl/m.m.j.meijer/D_I_Y/spc900nc.htm which were fine except he appears to have confused pins with pads (maybe its me) so I initially made the connections reversed. Works now though so I am looking forward to using LX mode.

I had to add a Serial-Parallel level converter as I didn't want to spend £85+ on a proper pin addressable USB-Parallel port device. Cheap ones only do printing. It's the chip with the two large resistors fixed to it.

Here are some pictures. All components from Maplin except the BW chip from Framos.de. Total cost about £45.

(All pics removed as links invalid - Dunc Jan2012)

[Ian]

neat piece of work that.

[Fay]

You are very clever Duncan! Now I hope you are outside tonight!!!!

[The Thing]

SkyWatcher AT80 400mm f4 at f4. Phillips SPC900NC BW LX Cooled. IR Filter. Unguided. 29/38 x 20s.

There was trailing and blurring and such forth but who cares, it works!

[JohnP]

Well done Dunc - I remember the immense satisfaction I did when I got first light with my Modded Toucam. Great Job & nice image... I look forward to seeing some more now its all working.

John

[RobertM]

Dunc,  that's really interesting.  I have the b/w chip to swap out the colour one - did you have any issues when you did yours ? 

[Fay]

Duncan, that is so good, what a result!!!!

[The Thing]

Robert, the only issue I had swapping the CCD was ensuring I got all the old solder out of the holes in circuit board. A pointy soldering iron tip and some solder wick sorted it out. Also very fine solder is useful for soldering in the new chip as its easy to connect to pins together inadvertently if you melt too much!

However the SPC900 took all the punishment I could throw at it and still works. I was guiding with it last night using 0.5s exposures to get six suitable guide stars near M81/M82 and I was able to get some more subs to add to my previous efforts.

I have had to use WxAstrocapture instead of PHD for guiding as PHD won't work with my serial circuit, I only see the long exposure image flash up intermittently between 'dark' frames of video. I can't work out how to Invert the RTS serial signal, which is what I am doing in WxAstrocapture with a check box. Any ideas?

[Ian]

is your lx mod based on a 74HC00? If so there's a spare nand gate on it you could use.

Alternatively, if you used the 4066, then you could build a discrete not gate with a transistor. See http://www.hanssummers.com/electronics/misc/gates/index.htm for some guidance.

[Ian]

that said, I'm a little surprised you're the only one having this problem. Have you tried contacting the author or checked out other websites for suggestions?

[The Thing]

It's the 74HC00. I wouldn't know what to do with the other NAND gate if it stood up and bit me. Presumably it can be used to reverse the switching effect???

I have joined the Stark Labs Yahoo group to see if I can find anything out. re: PHD Guiding settings.

[MarkS]

Well done Duncan - a satisfying piece of work there!

Mark

[Ian]

Pins 9 and 10 are tied to ground to stop them flapping. If you were to connect them both together to your RTS line, the inverted signal will appear on pin 8.

But, what circuit diagram did you use when you built the camera? The one you've got it sitting on appears to be from Matteu Meijer's site and that uses a 4066 chip. This diagram from Pete Katreniak's site:

has a discrete inverter (the transistor) on the RTS line so you'd do worse than to compare these two with what you used and play spot the difference...

[RobertM]

Hi Dunc,

After replacing the chip are you still able to use the standard SPC900 software with the camera ?

Robert

[The Thing]

Hi Robert,

The standard Vlounge app works, if I flip the LX switch it still works but the shutter defaults to the minimum (as it should). In wxAstroCapture I set DTR on LX Mask, LX Init and LX Frame check boxes and select Inverted Logic. There are no such options in PHD unfortunately. I can get Gazarollis Guidemaster to show images setting it to use DTR but not inverted (limited options) however this does not control the exposure length, only how often the 1/25s exposures are presented.

It's all very frustrating - I want a guide app that will allow telescope control via ASCOM and work with my modded webcam.