This modification is based on Steve Chambers SC1 long exposure modification. Steve figured out a way to make the modification, and was kind enough to share his discovery with us all and allow us to attempt the same.
THE ELECTRONIC PORTION OF THE WEB CAMERA MODIFICATION DESCRIBED ON THIS PAGE IS DERIVED FROM THE INTELLECTUAL PROPERTY OF STEVE CHAMBERS. IN RETURN FOR HIS KINDNESS IN FREELY SHARING THE DETAILS OF HIS INVENTION WITH US, HE ASKS THAT THIS INFORMATION IS NOT TO BE USED FOR PERSONAL GAIN OR COMMERCIAL PURPOSES (WITHOUT PRIOR ARRANGEMENT WITH HIM).
THIS MEANS THAT WEB CAMERAS MODIFIED ACCORDING TO THESE INSTRUCTIONS MUST BE FOR PERSONAL, NON-COMMERCIAL USE ONLY, AND MUST NOT BE SOLD TO OTHERS FOR PROFIT!
STEVE'S COPYRIGHT NOTICE IS HERE (AT THE BOTTOM OF PAGE). PLEASE READ IT! TO VIOLATE HIS COPYRIGHT IS A PROSECUTABLE OFFENCE, IT MAY BE ENOUGH TO KEEP HIM FROM SHARING HIS OTHER IDEAS AND INVENTIONS WITH US!
PLEASE COMPLY WITH HIS WISHES!
On this page I describe how I constructed the long-exposure modification for the ToUCam Pro II.
BEFORE YOU START BE WARNED!!!
IT IS POSSIBLE TO RUIN YOUR WEBCAM!!! Consider carefully whether you want to attempt this yourself. If you do, you do so at your own risk. You've been warned!! To get a better idea of what is involved and whether or not you are up to the challenge see Steve Chambers page about the scale of the job.
NO GUARANTEE IN GIVEN OR IMPLIED WITH THESE INSTRUCTIONS.
Well that's the legal bit out of the way so on with the show.
As I only needed the SC1 modification I have changed the circuit to use a single analogue switch device which only has eight IC pins as opposed to the fourteen on an 74HC00 or 4066 as used in the original circuits. The space saving may seem minimal but it was worth it.
In my modification I do not lift any of the IC pins but instead cut two tracks to isolate the pins of the PD16510. This does mean that there are now four wires to connect to the tiny IC pins in total. Instead of the original two wires on the IC pins + two wires on the IC pin pads, there are now two wires on the PD16510 and two on the SAA8116.
Making these connections requires a great deal of patience, a steady hand and a VERY fine tipped soldering iron.
DG418 Analogue Switch
2 x 10K Resistors
1 x 100K Resistor
1 x 470R Resistor
SPDT Switch (The smaller the better)
Small amount of Strip Board
Thin Connection Wire
1 x 25W 'D' type Connector Male (Parallel Port)
Length of single cored screened cable
|Maplins XR12N(1 core) XR91Y(4 core)|
The screened cable only requires a single core for the SC1 mod but if you think that you may later change the camera to SC2 or SC3 mod then use the four core screened cable. The length of this cable should be the same as the USB cable from the camera to the PC.
Since the modification requires some close-up work I used an eyeglass and some helping hands to hold the board to keep both of my hands free.
All work should ideally be carried out on an anti-static mat and using a grounded wrist strap to dissipate any static build up which could destroy the camera.
The circuit diagram of the modification is shown below.
The original camera - Philips ToUCam Pro II
The camera first needs to be disassembled. Firstly remove the base which is simply clipped onto the rest of the camera. Next remove the front cover which again is simply clipped on. At the bottom of the camera are two small black screws. Removing the screws allows the back cover of the camera to be unclipped and removed from the front.
The PCB is held to the cover by means of two more screws. Remove the screws and place the PCB on the anti-static mat for protection until required.
If the camera will still be required to be used for normal exposure use, then a switch needs to be fitted. I chose to mount the switch where the hole for the microphone was. I simply enlarged the hole to allow the switch to be fitted. The switch came with a tabbed washer to lock the switch in place. I made a small indent using a 2mm drill bit to fit the tab.
The switch connections would have fouled the camera PCB once it was refitted so the switch terminals were bent over. The centre terminal would not have bent in the required direction without the possibility of it snapping off so it was simply cut to length.
Some of the plastic of the front cover was removed to allow the control cable from the PC Parallel Port entry to the camera.
A similar cut-out was made in the rear cover of the camera for the same purpose.
The microphone is not required for astronomical use and since the shutter control switch has been fitted in its space it had to be removed. Simply unsolder the two connections to the microphone and remove it from the board. The large IC underneath the USB cable is the SAA8116, Digital PC-camera signal processor, which is one of the IC's involved in this modification.
After removing the microphone I tested the camera to ensure that it still worked.
The Red LED on the ToUCam Pro II is very small but also very bright, especially with the diffuser at the front on the camera. The LED could be removed altogether but I opted to simply cover it with black insulating tape. The IC to the left of the CCD is the PD16510, vertical driver chip, which is one of the IC's involved in this modification.
After taping the LED I tested the camera to ensure that it still worked.
Here comes the first tricky bit, attaching the four wires to the IC's. The two IC's in question are the SAA8116 which is next to the USB cable entry of the camera. The second IC is the PD16510 which is situated on the other side of the board next to the CCD. After connecting each wire I tested the camera to ensure that it still worked.
Make sure the wires are long enough to reach either the shutter switch or the interface board location, depending where they are going, and add a bit extra as well. There would be nothing worse that just having enough for the job and then cutting the cable by mistake when stripping it back meaning that you will need to connect a new wire to the IC (which may now be covered in glue).
The first wire I attached was the 'Shutter Control Reset Output' pin, PIN97. Since I could not get a good close up picture with my camera see the DATA SHEET for the exact location of the pin.
The pin on the top row at the right hand end in the picture is PIN 1. Pin 97 is the fourth pin down on the right hand side, as shown in the picture. Once the wire was successfully attached it was held in place using a small piece of insulating tape.
The next wire I connected was the second wire to the SA8116, the 'Vertical CCD Load Pulse Output' pin. Pin 93 is four pins below the first wire on the right hand side of the chip, (as shown in the photo). Once the wire was successfully attached it was held in place using a small piece of insulating tape.
The next pin was attached to the PD16510 Pin 10, 'VOD Shutter Drive Pulse Input' pin. Since I could not get a good close up picture with my camera see the DATA SHEET for the exact location of the pin. Pin 10 is on the bottom row farthest to the right in the picture. Once the wire was successfully attached it was held in place using a small piece of insulating tape.
The final pin was also on the PD16510 on Pin 8, 'PG1 Three Level Driver Input'. Pin 8 is two pins to the left of pin 10. Once the wire was successfully attached it was held in place using a small piece of insulating tape.
Now all of the wires were attached I fixed them in place using a small amount of silicon sealant.
Two track cuts are required to complete the modifications to the PCB. Both of the cuts are on the CCD side of the board and are fairly close together. Extra care must be exercised when cutting the tracks so that you do not cut anything other that the desired tracks. Be careful not to slip!
Before making the cuts I tested the wires that I had connected to the two IC's for continuity using a multi-meter. The table below shows which wires should show continuity.
|Wire||From||Via Uncut Track To||Wire|
|1||SAA8116 Pin 97||PD16510 Pin 10||3|
|2||SAA8116 Pin 93||PD16510 Pin 8||4|
Whenever I have to cut tracks I find that by placing the knife on the track, using the eyepiece as a guide, and exerting downward pressure helped in creating the cuts rather than the conventional cutting action which may lead to slipping. This procedure may need to be repeated a few times before the track gives in. I also usually cut the track in two places and remove the piece of copper between them to ensure a good cut. The board may need to be handled, other than in the helping hands, to allow the pressure to be exerted so make sure your anti-static wrist strap is on!
The PCB appears to be a multi-layered board, (more than just the top and bottom track layers), and as such do not make the cut any deeper than necessary to avoid cutting into the hidden layers. This is most unlikely to happen but I thought I should mention it.
To test the track cuts use a multi-meter to check for a LACK of continuity as per the table below.
|Via Cut Track To||Wire|
|1||SAA8116 Pin 97||PD16510 Pin 10||3|
|2||SAA8116 Pin 93||PD16510 Pin 8||4|
Now that the tracks are cut the camera will not work as before, so to test it I connected the wires together to make the camera electrically the same as before I started. Connect the wires as per the table above (Wire 1 to Wire 3 and Wire 2 to Wire 4). Luckily the camera still worked fine.
The interface board consists of an analogue switch (DG418) and two 10K resistors. See the DATA SHEET for the DG418. The board interfaces the parallel port control signal to allow the computer to control the switching of the CCD vertical shift buffer. The piece of Strip Board is only a matrix of 5x4 holes and the IC is 4x4!!!
The four hole width restriction is due to the space I had between the camera lens and the shutter switch. One set of the IC pins does not connect to the board through the holes in the board but are wrapped around the edge of the board to save precious width.
See the drawings below for details on making the interface board. Tracks that are required to be cut are shown as an 'X' in the drawing at the cutting point. There are two wire links on the underside of the board denoted by a thick grey line. The two 10K resistors are shown in the underside drawing. Position them as best you can without gaining too much height in the board.
Make the board in the following order.
|Make the required track cuts|
|Mount and solder the DG418 IC|
|Make the two wire links|
|Add the two resistors|
|Add the Parallel port cable connections.|
|Add the USB 0V and +5V wires|
The final board is shown below.
The 100K shutter switch resistor was fitted to the side of the shutter switch, with the other end connected directly to the interface board +5V. Unfortunately I did not take a picture of this step so I have drawn the position of the resistor and interface board on an earlier picture.
As can be seen the board is fitted with the IC touching the front cover of the camera and the pins pointing upwards. Once the board has been fitted the connections from the camera PCB can be made. Two of the wires go to the shutter switch, (on the remaining two free connections), and the other two go to the interface board.
|1||SAA8116 Pin 97||
|2||SAA8116 Pin 93||DG418 Pin 8 (2nd Row from Top on Interface Board Picture Above)|
|3||PD16510 Pin 10||
|4||PD16510 Pin 8||DG418 Pin 1 (First Row from Top on Interface Board Picture Above)|
Once the connections are all made, cover the interface board with insulating tape to stop any short circuits to the camera PCB. Recheck all connections before refitting the camera PCB.
With the camera PCB back in place all that is left to do is make the +5V and 0V connections to the USB connector. The USB connector has five wires attached and the +5V one is RED and the 0V one BLACK. Other modifications have suggested using the second black cable down and not the end one. I could see no reason for this as the USB cable only has four conductors and a screen, which is normally connected to earth (0V), and must be the fifth cable. When tested with a multi-meter the two black wires do appear to be connected to the same point on the PCB. That said I have fitted the 0V as per the other modifications. See the picture below for more detail.
Here is a slightly better quality picture of the final modification.
Before fitting the back cover a test was made to ensure that the camera worked as before when the switch was in the normal shutter control mode. Fortunately, in my case, all was well and I fitted the back cover.
Soldering the connections in the parallel port connector will be a 'Walk in the park' compared to what you have just been through. The Parallel port connector only has two wires connected. The 0V connection goes to Pin 21 and the control cable connection to pin 2 via the 470R resistor. The connector I used was the only one I had and the pins that have been cut, in the picture, are not a requirement of this modification.
Fitting the resistor here saved a little bit of space in the camera and has no effect on performance as it only limits the current between the PC and the camera and will do the same job no matter where it is located.
The camera is now ready for testing. As with other camera modifications I have taken a normal exposure picture, a long exposure picture in the dark, a dark frame and a final version of the long exposure picture with dark frame removal. All of the testing was done using K3CCD Tools http://www.pk3.org/K3CCDTools/ .
It has to be said that the room was pitch black, I couldn't see a thing myself. I think the pictures speak for themselves.
Picture with about 300W of candle bulbs
Long Exposure (15 Seconds)
Long Exposure Minus Dark Frame
All I need now are some cloudless skies :-). Check the telescope pictures page for images taken using the modified camera.
Any comments or questions then please e-mail me at the address below.
Good luck with any modifications you try.
Check out the Peltier cooled modification I am currently doing with the modified TouCam Pro II.
Copyright © 2004 - 2007 Phil Davis
Last updated 2nd December 2009