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I have built a circuit around 4 input signals from the pc printer port.

D0 = enable charge transfer pulse frame 1
D1= enable charge transfer pulse frame 2
D2 = On chip amp enable.
D3 = Shutter enable.

My thanks to Jim Talbot for the graphic.

An graphic by Ashley Roeckelein is here

(Notes in French by Jean-Pierre Bourgeay here and here)

The design is pretty modular so you can just connect up the bits you want. The chip I have built the circuit around is the 4066. Jean-Pierre Bourgeay introduced me to this chip with his simplification of the original circuit. I have chosen to keep the 4 signals separate, as this will give the software writers more flexibility. Firstly leads need to be connected to the D16510 chip. I won't go into details here as the connections are identical to the original mod except that the connection between pins 8 and 13 needs to be broken and connection made to each pin separately. The modifications to the D16510 connections control all features of the mod except the ccd amp.

To allow the ccd pre amp to be powered off a transistor is placed in series with pin 9 and its connection to ground. This part of the mod is easier than the work required to the d16510 chip but does carry a bigger risk of destroying the camera. The pre amp is powered from a 'fragile' 15 v supply. This comes into the ccd on pin 8. A couple of months ago I destroyed a ccd camera by accidentally grounding this supply. If you want to learn from my mistake, check very carefully connections you make in this area before connecting the power.

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The end of pin 9 has been bent to aid soldering

The control transistor can be mounted next to the logic chip and control the amp via flying leads but beware these leads don't get too long or come into contact with sources of interference. Alternatively you could mount the transistor directly to the chip. In the case of the vesta the easiest way to isolate pin 9 from ground, to allow the transistor to be inserted, is carefully cut the pin with a craft knife. The transistor leads can then be soldered to either side of the cut pin. Emitter goes to ground (best use the remains of the cut pin) and collector to the ccd pin 9.

To make my life easier, and because I had the bits to do it, I have put the circuit on a PCB. The pcb will easly fit inside the vesta case but see next page for a much better idea. If you would like to do the same the graphics are below. They should be printed out at 1.6x1.7 inch. Also the Express pcb file is here.

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If you will be shopping at Maplins the codes you need are:-

QB55K for the transistor although anything similar will do.
QX23A for the 4066B.

Both are stocked at Maplin shops

Also you will need a connector for the control lines. I have used 9 pin D connectors. 5 pin DIN or RJ45/RJ11 network type connectors would also make a good choice.
When choosing cable go for something lightweight and flexible.


If you are implementing the amp switch on a ToUcam add a 420ohm resistor between the collector and emitter of the amp control transistor.

If the addition of the amp switch transistor introduces diagonal banding to the images try either shortening the leads to the ccd from the transistor; or adding a 10uf capacitor again between the collector and emitter of the amp control transistor.

For more information on amp switching please follow these links.

William Behrens

Martin Burri

Peter Katreniak

Mike Kudenov



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See the full range of Atik cooled CCD cameras for astronomy on the Atik Website


Copyright 2006 Steve Chambers. All Rights

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