Carole's SC3 Webcam

[MarkS]

Following John and Mac, I'm the third person to look into the problem with Carole's Astronomiser SC3 modified webcam - the long exposure mode does not work on her laptap.

I've found the following:
* LX mode definitely works on my own laptop
* Using the same software (both GuideDog & K3CCDTools) and all the same settings, it does not switch to LX mode on Carole's
* During operation, using a meter, I can see the voltage being changed on the relevant serial pin as the software drives the COM port - both on my laptop and Carole's (but the voltage goes slightly higher on my own laptop).  So the software is definitely driving the COM port.

I reckon it may be a problem of voltage or timing of the pulses but I don't really have the expertise to take this further.

Is there anything else simple and obvious I should try? Or could it be that this particular camera is just incompatible with this particular laptop?

Mark

[Ian]

you have confirmed the BIOS has the parallel port configured correctly? I can never remember which it is you need but if yours in working, that'll be a template to work with

I suppose there's a possibility that the pull-ups in the camera are too low drawing too much current from the port, but that would be a serious error in the camera that could kill the port drivers in the laptop... Conversely, it might be that the port on the laptop has been damaged in some way. A PCMCIA parallel port card is available in Maplins for about 50 notes.

I did once have some software that allowed control of individual setting of pin states in the parallel port. I'll see if I can remember what it was.

[MarkS]

Ian - it's the serial port.

The BIOS only allows you to enable/disable it.

[Mike]

Does it have USB ports? If so how about trying a USB-Serial convertor cable?

[Ian]

you know what. I made that mistake last time too...  

what voltage are you seeing on the port with the camera connected (if you can get a meter probe to it)? It does look like the port driver is not driving properly. Have you got a usb-serial port to try? I've got one you're welcome to borrow.

If the circuit used is similar to this Thanks to Peter Katreniak then I would investigate the resistor limiting current into the transistors. If this resistor is too high there won't be enough current supplied to the base of the transistor to fully turn it on. It might be that the camera has a different circuit for inverting and level shifting the signal, but even so, if the laptop port isn't driving hard enough (and alot of them don't as part of power management) it's not going to work.

Has Carole given you the go-ahead to take the camera apart? If not, I'd recommend dropping it from a height of 1.295m onto a surface with a Brinell Hardness of 1.6. That aught to do it  

[MarkS]

No, I'm not going to dismantle the camera!

Yes, I'd love to borrow your USB-Serial port.  If it works then we have identified a feasible solution.

Mark

[Ian]

No, I'm not going to dismantle the camera!

You're no fun

I'll dig the adaptor out when I get in from work. I should have a driver CD for it too, if not I'll stick them on a USB key for you. When would you like to pick it up?

[MarkS]

Thanks, Ian. Is sometime this evening convenient?  Send me a PM with your address.

Mark

[MarkS]

Thanks Ian,

The Webcam LX mode worked first time on Carole's laptop when using the USB-Serial adaptor - with both GuideDog and with K3CCDTools. 

So we have a potential way forward.

Mark

[Ian]

cool

[Mike]

Must be a snookered USB port then. Wonder how that happened.

[Ian]

nope. under-spec built-in serial port...

[Carole]

Blimey guys, I had no idea all this was going on yesterday until Mark contacted me, as I never logged into the Forum all day being pre-occupied with other things.

Thank goodness for friends like yourselves and Mac and John who previous helped, I would never have fathomed this all out and the thread above goes way over my head.

Hopefully once I get the lead which Mark has kindly ordered for me I can now start to try to do some DS imaging.  I was on the brink of giving up and getting a DSLR instead. 

Many thanks

Carole

[Mike]

nope. under-spec built-in serial port...

No USB port?! Where did this laptop come from? The Science Museum??

[Ian]

mike, it's time to lay off the sauce in the morning...

There's nothing wrong with the USB ports, but being an SC3 camera it connects to USB for video and a serial port for exposure control. I thought you knew that.