Building the CB245 CCD camera







Introduction
You can make the CB245 camera, also called Cookbook camera, by yourself. It’s not very difficult if you know a little about electronics.

Richard Berry, Veikko Kanto and John Munger developed two CCD cameras, the CB211 and CB245. These cameras are relative easy to make and are comparable with cameras you can buy in a store, but they are much cheaper!!! I made the CB245 camera and it cost me about 300$ (USA), but you can spend a bit more or less. The CB211 is the simplest and cheapest one, but can’t be used with lunar and planetary photography without a shutter.

You will only need a simple PC to control the camera, a XT (8086) can do the job, but an 80286 or 80386 is better.


Building
The first thing you need, to build one of the cameras, is the ‘CCD Camera Cookbook’, made by the developers. It describes how you can make the camera and how it functions. It also delivers software that helps you building and testing the camera and also acquisition software to control the camera. The second is to order the electronical components, or available sets of electronics. The ‘Cookbook’ gives information on where to order the components. Than you can start building.

The test software is very important. The electronics are made in a couple of phases. Between every phase, the test software lets you verify resistances and voltages on the board you are making. If there would something be wrong, you would notice it with the tests. After you completed all tests, your camera should work. This is also my experience.

Main parts of the CB245 camera:
  1. Power supply
    This unit gives the camera it's power of +15V and -15V. It's easy to make.

  2. Interface card
    This unit connects the computer to the preamplifier. It converts the computer signals and also the analog signal from the CCD chip to a digital format.



    The interface card from inside.


  3. Preamplifier
    This unit is mounted on the camera body. It amplifies the analog signal from the CCD chip and converts the clock signals.

  4. Camera body
    The camera houses the CCD chip.

    The camera and preamplifier are on the left, and the interface card is on the right.


    The electronics from inside.



Technical Specifications
The CB245 uses a TC245 CCD chip and the CB211 a TC211 CCD chip, both from Texas Instruments.

Chip TC211 TC245
Total pixels h. 192 755
Total pixels v. 165 424
Size h. (mm) 2.6 6.4
Size v. (mm) 2.6 4.8
Pixel size h. (m) 13.75 8.5
Pixel size v. (m) 16.0 19.7

The TC245 has very rectangular pixels. This is because it was originally made for TV imaging. Normally, horizontal pixels are combined. Combining two pixels gives 378 horizontal pixels and combining three pixels gives 252 pixels.


Cooling
Cooling of the CCD chip is used to reduce thermal noise. This is not very important with lunar and planetary photography, so you don’t have to build it. It is only interesting with integration times of more than a few seconds.

LDC mode
A modification to the original CB245 camera was made to reduce the thermal noise (LDC = Low Dark Current). This is also not very important with lunar and planetary photography. But if you want it, it’s easier to make than cooling. Don’t use it with lunar and planetary photography, it has a negative effect on your images. Luckily, it can be switched on and off with the acquisition software. With planetary photography, LDC mode is only interesting when you want to photograph faint moons.