Camera CCD fabriqué maison "CAM86"

[Cedric02700]

Je viens de remplacer DD11 par un régulateur un peu plus costaud (MC78M06 0,5A). Un offset avant avec C30=80uF et un chimique de 100uF en parallèle:

 

 

Avec le nouveau régulateur et C30=80uF seul:

 

 

Avec le nouveau régulateur et C30=330uF seul:

 

 

Niveau bruit de lecture pas de différence significative.

[luka]

I noticed that the vertical lines get worse if 2x2 the binning is used. The sensor may be pulling more power as it has to read more pixels at the same time???

 

If you are adding extra capacitors make sure they are as close as possible to the pins on DD8.

Modifié 8 février 2018 par luka

[pagpatrice]

Je viens de remplacer DD11 par un régulateur un peu plus costaud (MC78M06 0,5A).

 

Niveau bruit de lecture pas de différence significative.

 

Je m'attendais vraiment à mieux

[luka]

A question for people with Cam86:

Is anyone using the humidity sensor? If yes, how useful is it?

 

The support for the humidity sensor has been removed from Cam90 and I am thinking of doing the same for Cam86 (this may improve the cooling).

[gehelem]

A question for people with Cam86:

Is anyone using the humidity sensor? If yes, how useful is it?

 

The support for the humidity sensor has been removed from Cam90 and I am thinking of doing the same for Cam86 (this may improve the cooling).

Hi Luka

I did (on my first one)

I will (on my second one)

I find it useful to know when it's time to change silica gel

But i can do without (CCD freezing => time to change )

 

I don't understand why it might improve cooling : is it because of removing continuous reading values on DHT22 ??

[luka]

Hi Gilles,

 

Rim (grim on the Ukrainian forums) has changed the cam90 cooling to also work during the frame reading. This improved the temperature stabilisation, especially when taking short exposures, for example for live view or the acquisition of flats.

(He has also removed the support for the humidity sensor)

 

I was thinking implementing the same cooling improvement to cam86. However, cam86 is different and we possibly have to remove the support for humidity sensor. I am not sure, this is all theory at the moment and it may not work for cam86. But before starting I wanted to see how many people actually use the humidity sensor and how useful it is.

 

By the way, I am not sure if the possible removal of the humidity sensor for cam86 is related to the removal of the humidity sensor for cam90.

 

 

What humidity is your DHT22 showing when everything is fine and what is it showing when cam86 needs silica gel change? Also how often do you need to change the silica gel?

 

Thanks

Luka

[luka]

Hi,

 

As we know cam86 cannot control the temperature during the 2 seconds frame reads but cam90 can. I have been thinking about the possible solution for this.

 

The reason for this is that Cam90 uses pin PB1 of Atmega for the cooling which supports hardware PWM while Cam86 uses pin PB0 which does not support hardware PWM. So Cam86 has to control the pin/cooling in software and this is not possible during the frame reads. This is not a problem for long exposures but I found that the temperature changes a lot when using LiveView or when taking flats.

 

A possible solution would be to cut tracks and use bridging wires to "swap" the Atmega pins PB0 and PB1 on the Cam86. This is difficult to do and it requires good soldering skills.

(If the DHT22 sensor is not used then only half of the soldering needs to be done)

 

I would change the firmware to include proper cooling during frame reads, like Cam90 does. Rim mentioned before that this did not affect the camera noise.

 

Is anyone interested in the change?

[pagpatrice]

Hi,

 

As we know cam86 cannot control the temperature during the 2 seconds frame reads but cam90 can. I have been thinking about the possible solution for this.

 

The reason for this is that Cam90 uses pin PB1 of Atmega for the cooling which supports hardware PWM while Cam86 uses pin PB0 which does not support hardware PWM. So Cam86 has to control the pin/cooling in software and this is not possible during the frame reads. This is not a problem for long exposures but I found that the temperature changes a lot when using LiveView or when taking flats.

 

A possible solution would be to cut tracks and use bridging wires to "swap" the Atmega pins PB0 and PB1 on the Cam86. This is difficult to do and it requires good soldering skills.

(If the DHT22 sensor is not used then only half of the soldering needs to be done)

 

I would change the firmware to include proper cooling during frame reads, like Cam90 does. Rim mentioned before that this did not affect the camera noise.

 

Is anyone interested in the change?

 

HI Luka,

I've been talking about this change a long ago , personally I do not use a humidity sensor and I think a real PWM would be beneficial.

[luka]

Hi Patrice,

 

I have been thinking about the real PWM for a while but it was not possible to do so because the TEC pin in Cam86 did not support it. Only a few days ago I thought about cutting tracks on the PCB and "swapping pins".

 

The support for the humidity sensor can be retained even after this modification, it will just need soldering an extra wire.

[gehelem]

Hi Patrice,

 

I have been thinking about the real PWM for a while but it was not possible to do so because the TEC pin in Cam86 did not support it. Only a few days ago I thought about cutting tracks on the PCB and "swapping pins".

 

The support for the humidity sensor can be retained even after this modification, it will just need soldering an extra wire.

 

Luka, do what you like, i don't really need humidity sensor, it's just for setup time...

there's engough place for an Arduino and if i ever really need it

But can you keep your code somewhere, just commented ?

 

And be carefull, this forum will be down in the next few days, for upgrade :

i'll watch IIS forum if we need more explanations...

 

Gilles.

[Cedric02700]

A question for people with Cam86:

Is anyone using the humidity sensor? If yes, how useful is it?

 

The support for the humidity sensor has been removed from Cam90 and I am thinking of doing the same for Cam86 (this may improve the cooling).

 

The humidity sensor is convenient but not essential. If to ameliorate the cooling it is necessary to dispense with the humidity sensor, that suits me.

 

I would change the firmware to include proper cooling during frame reads, like Cam90 does. Rim mentioned before that this did not affect the camera noise.

 

Is anyone interested in the change?

 

The modification interests me. Thank you!

[Cedric02700]

Première image pour moi avec la Cam86! J'ai choisi IC410.

Coté prise de vue:

-Monture Neq5 + AstroEQ

-Newton sky watcher 150/750

-Cam86 avec le capteur N/B et filtre Ha 7nm

-23 pose de 900" (5h45)

-225 offsets

-31 Darks

-Pas de Flats. J'avais fait une série à 21000 ADU et une autre à 37000 ADU. Dans les deux cas , ils dégradent l'image... A voir.

-Traitement Siril et Photoshop

 

Je débute en traitement. Voici un premier jet traité vite fait avant le black out du forum:

 

 

Je pense que des poses de 1200" auraient été plus adapté à la luminosité de l'objet.

[gehelem]

Champion !!!

[impla007]

Waouu des poses de 900" et 5h45 .. Je crois que tu détiens le record avec cam86.

 

Ça veut dire Qu elle marche drôlement bien et Qu elle est fiable

[pagpatrice]

Superbe ta IC410, tu dois pouvoir gratter un peu plus dans les nuages mais attention aux étoiles elles sont déjà à la limite.

 

En tous cas pour une première tu frappe fort .Les seules étoile que je verrais ce soir sont celles de neige, on en est à plus de 10 cm et ça continue .

[Cedric02700]

Champion !!!

 

Merci!

 

Waouu des poses de 900" et 5h45 .. Je crois que tu détiens le record avec cam86.

 

Ça veut dire Qu elle marche drôlement bien et Qu elle est fiable

 

Merci. J'ai pas encore battu le record, sur AstroBin la concurrence est rude! C'est vrai qu'elle est fiable et le driver de Luka une merveille! Pour l'instant pas de photos à la poubelle a cause de la camera.

 

Superbe ta IC410, tu dois pouvoir gratter un peu plus dans les nuages mais attention aux étoiles elles sont déjà à la limite.

 

En tous cas pour une première tu frappe fort .Les seules étoile que je verrais ce soir sont celles de neige, on en est à plus de 10 cm et ça continue .

 

Merci. J'ai essayé d'en avoir plus de nébulosités mais les étoiles prennent une claque. En même temps à part les niveau et luminosité/contraste j'ai pas touché à grand chose. Je vais prendre des cours de traitement et ça ira mieux! Bon courage pour la neige!

[Cedric02700]

Une petite V2 pour la route et j’arrête.

 

[pagpatrice]

Une petite V2 pour la route et j’arrête.

 

 

Touche plus a rien, elle est parfaite, bravo

[luka]

Hi everybody,

Good to see that this forum is back. I have been waiting, waiting and waiting as I have several issues to discuss. I will split them into separate posts.

 

1. The capacitor C30... I have seen lots of discussion about it as it is the cause of the vertical lines on the left of the image.

I am not sure which value people have used but the original capacitor GRM31CR60J107M is a MLCC capacitor and its capacitance changes with the bias voltage applied. At 6V in Cam86 it only has 20% of the rated 100uF capacitance, i.e only 20uF.

 

I would suggest a large tantalum capacitor but with at least 10V rating. Tantalum capacitors need to be derated in voltage by 20%-50%, depending on the type, otherwise they can explode. 6.3V is too close and the next highest voltage rating is 10V. The best I could find was 10V, 100uF tantalum. I have not tested it yet.

 

If you do not get vertical lines on the left of the image, try taking a 2x2 binned image or try stacking >20 bias files. The lines will likely reappear.

[luka]

2. Another driver version is out, v0.7.10. Get it from here.

I added some delays in the camera initialisation code. Previously too many commands were sent too quickly and some were lost as the ATMega did not have enough time to process it all. You may notice a slight delay only when you first connect to the camera, otherwise the functionality is the same.

No changes to the firmware.

[luka]

3. The switching of TEC during the frame reading... where to start.

 

It is possible to switch the TEC during the frame read in software. The frame is read line by line (1000 times) and I can switch on/off TEC in between the line changes. No hardware modification of the camera would be necessary for this.

 

However, if the TEC is switched during the frame read on my camera I get horizontal stripes in the image. I have attached an image of stacked 10 bias files where the TEC was switched on/off at lines 250, 500 and 750. The 4 horizontal stripes are visible where the switching occurs. 

The stripes are present in the single images as well but not as clearly. Rim mentioned similar problems for Cam90.

(Also of interest are the vertical lines on the left which I do not see in the individual images)

 

I need other people to test the effect of switching during the frame read. If we cannot get rid of the stripes then we cannot have switching of cooling during the frame reads.

 

The attached firmware will switch the TEC on/off 4 times during the frame read, at lines 250, 500, 750 and 900 (the striped pattern will be slightly different than mine). The switching is independent of the cooling and will be done at every image taken.

 

Can you please:

1. Upload the testing firmware to your camera

2. Cool the camera to less than 5 degrees C. Otherwise the thermal noise can make stripes difficult to see.

3. Take a bias image.

4. If there are no stripes visible (after stretching the image) please take 10 more and try stacking them.

4. Let me know if the stripes are visible in the individual bias files and in the stacked bias file. If possible post an image here.

5. If there are no stripes you can try the same at sub-zero temperatures.

6. If you still have no stripes then did you do any modifications to the original design? Is the cold finger grounded? What thermal paste was used (electrically conductive or not).

 

Also, I know that someone did some modifications to the TEC circuitry to solve USB issues but unfortunately I do not speak French and cannot use the search function. This may help with the stripes, not sure???

 

When finished do not forget to flash the original firmware back (https://github.com/axsdenied/cam86_fw).

DO NOT USE THIS FIRMWARE for your real photos, they will be ruined. This is only for testing.

 

 

cam86.zip

[Cedric02700]

Il y a 22 heures, luka a dit :

3. The switching of TEC during the frame reading... where to start.

 

It is possible to switch the TEC during the frame read in software. The frame is read line by line (1000 times) and I can switch on/off TEC in between the line changes. No hardware modification of the camera would be necessary for this.

 

However, if the TEC is switched during the frame read on my camera I get horizontal stripes in the image. I have attached an image of stacked 10 bias files where the TEC was switched on/off at lines 250, 500 and 750. The 4 horizontal stripes are visible where the switching occurs. 

The stripes are present in the single images as well but not as clearly. Rim mentioned similar problems for Cam90.

(Also of interest are the vertical lines on the left which I do not see in the individual images)

 

I need other people to test the effect of switching during the frame read. If we cannot get rid of the stripes then we cannot have switching of cooling during the frame reads.

 

The attached firmware will switch the TEC on/off 4 times during the frame read, at lines 250, 500, 750 and 900 (the striped pattern will be slightly different than mine). The switching is independent of the cooling and will be done at every image taken.

 

Can you please:

1. Upload the testing firmware to your camera

2. Cool the camera to less than 5 degrees C. Otherwise the thermal noise can make stripes difficult to see.

3. Take a bias image.

4. If there are no stripes visible (after stretching the image) please take 10 more and try stacking them.

4. Let me know if the stripes are visible in the individual bias files and in the stacked bias file. If possible post an image here.

5. If there are no stripes you can try the same at sub-zero temperatures.

6. If you still have no stripes then did you do any modifications to the original design? Is the cold finger grounded? What thermal paste was used (electrically conductive or not).

 

 

Hi Luka.

 I made the test of firmware.

1. OK

2. Temperature 1°C

3. One bias image

 

 

Thank you and good luck!

Modifié 20 mars 2018 par Cedric02700

[luka]

Thank you Cedric.

The stripes indicate similar problems as with my camera.

I will wait for someone else to confirm with their camera but it may not be possible to switch TEC during the frame reads

Maybe if we add an inductor to smooth the current during the TEC switching???

 

Did you ground the cold finger? What kind of thermal paste did you use? I tried grounding the cold finger and the camera did not even start.

[pagpatrice]

Hi Luka,
yes it was long without webastro but it is more beautiful now  , to answer you:

1- yes a tanatale is very good, with my 6.3 V I had no problem but since I solder a 100μf directly on the pin 16 DD8 and since more problem.
  2- I saw on IIS, but did not have time to install it yet, not much time for astro right now
3- I would do in the weekend, and for the modifications of the problem USB, it is Impla007 who had posted this:
https://www.webastro.net/forums/topic/148427-camera-ccd-fabriqué-maison-quotcam86quot/?do=findComment&comment=2337576

 

If you are looking for something on our forum, do not hesitate to ask, with the new interface that may be more difficult for a not french, also the first message, I created a summary to make it easier to find everything .

Modifié 20 mars 2018 par pagpatrice

[Cedric02700]

Il y a 4 heures, luka a dit :

Did you ground the cold finger? What kind of thermal paste did you use? I tried grounding the cold finger and the camera did not even start.

 

I did not grounded my cold finger. My thermal paste is not conductive.

Modifié 20 mars 2018 par Cedric02700

[luka]

New driver update is out, version 0.8.0. Get it from the usual place.

 

Changes:
1. The cooling power % is shown in the info section now (next to the temperature).
2. Image minimum, maximum and mean are displayed now.
3. Sped up the image processing time. Each image will be taken about 0.2-0.3 seconds faster now.
4. Several interface improvements.
5. Minor bug fixes.

 

Enjoy and please report any bugs and suggestions.

 

Still working on the TEC switching, no new updates yet.

[luka]

More information about the horizontal stripes:

1. They are not noise caused by the TEC switching. If I set the switching to be very slow (once a second) the stripes stay at the same intensity for the whole 1 second. Any electrical noise caused by the switching would not last that long.

2. They feel more like the gain or offset or some voltage is slightly changing, hence the darker/brighter stripes. Or some capacitive effect???

3. I measured voltages with oscilloscope to try to find any variations that happen at the same frequency as the stripes. I did not find anything but it is very difficult to detect small voltage variations on large base voltages.

4. If we use higher frequency the stripes start losing their sharp transition edges. Unfortunately we don't have proper PWM on the pin controlling the TEC and we cannot manually change the TEC pin fast enough during the frame reads. The stripes are clearly visible even if the TEC is switched on and off at every line change (1000 lines in 2 seconds).

5. The intensity of the stripes can be reduced if the cold finger is electrically connected to the back of the sensor by using an electrically conductive thermal paste, like Arctic Silver 5. However, they are still present.

6. If the cold finger and the back of the sensor is grounded the camera will stop working.

 

So, unless someone figures out what is causing the stripes I don't think it is possible to use the current TEC pin to have manual PWM during the frame reading.

Rim said:

Citation

The peculiarity lies in the fact that it is necessary to properly connect the power wires supplying the "+" and "-" peltiers to the source of the power switching transistor, otherwise there will be some banding of the image. It is necessary to drive these wires separately from the input connector and it is better to use a separate connector for powering the cooling power section.

 

 

Cam90 uses a different pin for the TEC control and that pin has PWM. TEC is switched at about 500Hz and the stripes are not visible. So the only option for us would be to use the humidity sensor pin (which supports PWM), cut traces on the board and wire it to the MOSFET that switches the TEC. Or alternatively wire the humidity sensor pin to a separate MOSFET that is not mounted on the board - this would mean that no traces need to be cut.

[Cedric02700]

Le 19/03/2018 à 17:07, luka a dit :

3. The switching of TEC during the frame reading... where to start.

 

It is possible to switch the TEC during the frame read in software. The frame is read line by line (1000 times) and I can switch on/off TEC in between the line changes. No hardware modification of the camera would be necessary for this.

 

However, if the TEC is switched during the frame read on my camera I get horizontal stripes in the image. I have attached an image of stacked 10 bias files where the TEC was switched on/off at lines 250, 500 and 750. The 4 horizontal stripes are visible where the switching occurs. 

The stripes are present in the single images as well but not as clearly. Rim mentioned similar problems for Cam90.

(Also of interest are the vertical lines on the left which I do not see in the individual images)

 

I need other people to test the effect of switching during the frame read. If we cannot get rid of the stripes then we cannot have switching of cooling during the frame reads.

 

The attached firmware will switch the TEC on/off 4 times during the frame read, at lines 250, 500, 750 and 900 (the striped pattern will be slightly different than mine). The switching is independent of the cooling and will be done at every image taken.

 

Can you please:

1. Upload the testing firmware to your camera

2. Cool the camera to less than 5 degrees C. Otherwise the thermal noise can make stripes difficult to see.

3. Take a bias image.

4. If there are no stripes visible (after stretching the image) please take 10 more and try stacking them.

4. Let me know if the stripes are visible in the individual bias files and in the stacked bias file. If possible post an image here.

5. If there are no stripes you can try the same at sub-zero temperatures.

6. If you still have no stripes then did you do any modifications to the original design? Is the cold finger grounded? What thermal paste was used (electrically conductive or not).

 

Hi Luka

 

I like the new features of the new driver! I'm ok to test the PWM cooling with or whithout external MosFet. Thank you!

 

Modifié 27 mars 2018 par Cedric02700

[pagpatrice]

I did not have time to do the test, but I think that the humidity sensor is a gadget that does not serve much, so very little commercial camera uses it.

for my opinion to choose between moisture sensor or PWM the choice is simple the PWM would be a great improvement 

 

[gehelem]

Same for me, i agree with Patrice 

Gilles