This page is hopelessly out of date, and should be revised completely. Due to systematic lack of time i need to set priorities, and this camera is currently quite low on the list. Note that it has never been built by me, and probably never will be either. I now have a toucam which should yield similar results
For people who are interested i have a more up to date design Eagle format, including schematics and an attempt of a PCB layout.
CCD-237 is a design of a camera for astronomic imaging, based on the TC237 chip by Texas Instruments. It has not yet been implemented, and as such no guarantee on its correctness can be given.
Design details of the CCD-237 can be found on pages about:
The reason i decided to design my own camera is that i could not find an existing one that completely satisfied my wishes. My requirements for this camera were as follows:
- Single camera module: no external adapter boxes, apart from a PSU. This means that no complex interface is required, since outside the camera module everything is digital.
- Direct PC control through printer port: to avoid complex clock circuits on the camera module. A parallel printer port is available on about every type and version of PC. This solution does not give the fastest interface, but the TC237 is of the frame transfer type so for image quality read-out dedlay is not really an issue. Realtime video is not required for astro imaging anyhow.
- Simple design: use as little components as possible, and avoid using exotic components. Straightforward and easy to understand design limits the chance on failures.
- Powered by mains and car-battery: the camera module should synthesize the necessary voltage levels from a straightforward symmetric +/-15V power supply. The peltier element may have its own supply, and can optionally be left off (or out).
Some characteristics of the TC237:
- 7.4 um square pixels,
- VGA form factor: 640x480 pixels
- Read-out noise: 10 e-
- Conversion factor: 20uV/e
- Full well-depth: 30,000
- Dynamic range: 70 dB
- Not expensive: $75
The TC237 may not be as suited for astro-imaging as for example the KAF400, but the main advantages are that it is of the frame transfer type, and that it is much cheaper.
The system block diagram shows the Camera Module, the PSU and a PC (laptop) to control the camera and to collect the data. The interface to the camera uses the laptop parallel printerport. To simplify the design of the camera the printerport output signals are used to directly clock the CCD and the ADC.
Other CCD camera designs:
- There is one more TC237 (and TC255) based camera design available on the web: Kitty 237/255. I consider the design quite complex, mainly due to the analog camera / adapter box interface.
- There is some more information available on TC255 and TC211 designs from Club ASNORA.
- The all time favourite Cookbook 211/245 camera design (TC211 and TC245) available in book form only.
- Another design, based on Kodaks more expensive KAF401, is the "Audine".
Both the KAF401 and the TC245 will be discontinued. The design of CCD-237 is to some extent based on the information found on the web.