Logitech Quickcam VC long exposure modification.

Introduction

The following pages detail the steps I took to make my Quickcam VC (parallel) capable of long exposures. Now I'm not sure how this modification will perform in other situations but it works for me, so far I have tested it on two of my PC's and it has worked. I think this was pretty pioneering work with the Quickcam VC, as I couldn't find anything else on this camera, so if you are successful in working on it please let me know.

In the end the camera was controlled via a serial line driven by Astrovideo. Here I must give thanks to Dr. S.J.Wainwright (site here) and Bev Ewen-Smith (site here) for all their help to develop this modification.

Disclaimer

Be aware that you will invalidate the warranty of your camera if you attempt any of the modifications you read about on this site.

No warranties of any kind are given or implied that the modifications shown on this site will be safe either for the camera or the computer or other equipment to which it may be attached. All that can be said is that the modification, as described, has been found to work.

It is each individual's responsibility to decide whether they wish to experiment with their equipment in ways described here.

Do not try to blame anything that may go wrong on anyone but yourself. It is on this understanding and this understanding alone, that the results of modification experiments are shared with others.

Some background

I was doing some research into CCD astrophotography when I found the Steve Chambers modifications and the good QCUIAG (QuickCam & Unconventional Imaging Astronomy Group) site. I had already got the QC VC so whilst reading through these pages things didn't look good for getting long exposures from this web cam. Anyway as this sort of work appeals to me I set about finding data sheets for the various ICs that I could see where connected with the CCD chip. Here was some more bad news:

There are 3 main ICs to deal with the CCD control:
There's a Exar 4460 chip which is a image digitizer, with some processing. Managed to get data sheet.
There's the Orbit 61509A this seems to be the main control. No data sheet.
Then there's the CDD, Sharp LZ2547. Got a data sheet.

Reading the Steve Chambers introduction to CCDs I saw I had to block the transfer gate pulse and keep the Shutter high. The only data sheet of help was the Sharp (download here). I found the TG and Shutter pins and traces and tracked them back to a convenient breaking point. The point I chose was the legs on the Orbit chip.

Onwards to the work I have done. Before we start I am sorry for the quality of the picture.

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