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  #81  
Old 15-07-2016, 12:19 AM
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I was looking for ways to control moisture inside the enclosure and came across these. There are 3 different sizes.
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  #82  
Old 15-07-2016, 08:56 AM
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IHi Luka

I haven't done any measurements so far but the sensor is 28.4mm diagonal, however, the pixel array is smaller than the package. I think Gary mentioned 26mm filters. I'm staying with colour bayer atm, but, If I get 2 running, one will go under the knife for some de-bayer action!

That's a dam good idea for silica gel. I think sealing the case might be a real issue. We only need to seal the sensor area, which is also not an easy thing. I suspect we will not get it fully sealed. I have read (an IIS user) who had sensor dew issues and he used a small piece of tube to direct some of the TEC cooler hot air over the sensor. Apparently it worked.

Finished drawing schematic of cam86 with eagle PCB. I'll now cross check parts on the schematic to the PCB images.
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  #83  
Old 15-07-2016, 08:18 PM
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I have spent last two years battling humidity, salt and water in devices (at work)... it is much more difficult problem due to salt...

Anyway, we should try to seal the sensor area as good as we can and then also seal the whole camera. A thin layer of silicone around the joints will ensure no air gaps. If you pick the right silicone it can be removed without much drama when camera needs opening.

Then there are few ways to prolong the operation time. You want to close the box with as little humidity inside as possible and then there is a possibility of a leak.
Silca gel bags (in little cages) will work fine but I like the ones from RS as they screw into the housing and have an outside indicator. In other words you know when the humidity is too high inside and you can take them out for baking without taking apart the housing. I just found them and have not used them yet. May be too bulky though.

If you look at some of the 450D cold finger builds (I just finished mine), there is lots of discussion about this. The other idea is to fill the camera with dry gas, for example with argon (easy to get from Bunnings). This will help a bit as well.

Finally, we could put a humidity sensor inside and measure humidity this way. If it goes too high, time to look for leaks, replace the silca gel, and refill with argon
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  #84  
Old 15-07-2016, 09:09 PM
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I forgot to say, my CDX1267ANs arrived today. No stickytape anywhere and properly packed

Got them from here.
Attached Thumbnails
Click for full-size image (CDX1267AN.jpg)
77.9 KB24 views
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  #85  
Old 16-07-2016, 09:41 AM
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Hi luka

I would have though that the the electronic humidity sensors are too big to fit in the case, near the sensor area?

I ran a cooled 450D, al la Gary Honis style (camera in a TEC coolbox) and it worked well, took lots of time to cool down, but would cool to below 0 C. I kept the sensor free of moisture by wrapping a dew heater on the camera/drawtube nosepiece. I used to find ice in the case area after use. Mostly the electronics doesn't ice up as they are slightly warm from passing electrons.

We can conformal seal the PCBs to protect them but I guess no matter what we do, sealing the case is a priority. Gary has some ideas on this, like "FADDYs" camera build. I see the cover filter as the most difficult area to seal, "sealing the UV/IR filter". We absolutely need to backfill the case with an inert gas, probably Argon. I guess we should pressure check them first. This is probably best with the sensor out as we don't want to damage it. I don't know what pressure differential the sensor coverglass can be subjected to.

I looked at the RS silica Gel Desiccators and my guess we need the small 10gram version, mainly due to the mounting hole size (17mm ). I saw some IP67/IP68 sealed "D" connectors, like this. I'll do a search for more or cheaper units but these look as good as we can get to seal the housing electrical connector. Which means we might need a small breakout box (like "FADDs") on the back of the camera to convert this "D" sub out to power, USB etc.

Can I ask where you got the CXD1267?

I'll get back on connectors and do some sealing case/UVIR filter research.
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  #86  
Old 16-07-2016, 12:17 PM
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Quote:
Can I ask where you got the CXD1267?
See the ebay link in my post above
Interestingly the ebay feedback was in German but the CXD1267 were apparently sent from Hong Kong. And I paid in Euros.
The postage is a bit steep, ordering some spares is advised. I have three, i.e. one spare assuming I make two cameras.

Regarding the waterproof electrical connectors, I should have offered my help before, I can easily find some. Somehow my brain didn't register that you were looking for them. Sorry. Too many things to think about...

Do we know what connectors we will have coming out of the box?
1. USB (I actually bought one of these yesterday, or this? A bit bulky but we could probably find space for it).
2. Power (what kind, i.e. how many connectors/voltages)?
3. Anything else?
Will the Peltier sit on the outside of the box, i.e. will it be powered from the outside? I assume it will be PWM controlled and that can interfere with the other communications (USB for example). It may be the best to keep them on separate connectors.


The electonic humidity sensors are bulky (this for example). You are right, they would not fit in the small space where the sensor is but could be used to measure humidity inside the case. We would also need a small controller... You went through all the Cam86 circuitry, does the build have any provisions for connecting temperature sensors? I don't believe they will release the source code for the firmware, otherwise it would be trivial to modify the ATmega code to include temperature/humidity sensor or whatever else we want.

If you are worried about the sealing the front window, here is a different idea... When I mentioned the 450D cooling mod, I meant the cold finger mods. Two different approaches were used to combat the fogging up of the sensor:
1. SMD resistor array to heat up the front of the sensor
2. Astronomik MC-clear glass in front of the sensor. It created a sealed chamber that was filled with argon.
We could 3D print a small plastic spacer, glue the MC-clear glass to it and then place it on the sensor (under argon atmosphere). This will create another sealed chamber providing extra thermal insulation.
It increases the cost significantly as the 450D glass was about $100 when I bought it about a month ago.
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  #87  
Old 16-07-2016, 01:42 PM
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Hi luka

I was looking more at the D sub sealed connector as it is not just moisture sealed it has glassified epoxy on the backshell around the pins. Thus its environmentally sealed, well, in a manner, and a flange seal, which will seal air inside, hopefully. Funny enough the RS USB sealed connector looks to be the goods! My guess you're right up this field already.

The peltier can sit outside the box and a cold finger (Slug) arrangement to the sensor but mostly I have seen them directly on the sensor. Since he's put peltier control on the PCB I suspect they are looking at locating the TEC in the case against the sensor.

I'm sure we can seal the front glass, depends on the mating arrangement. RTV3145 or such like.

Cam86 uses a DS18B20 sensor which can operate more than one on a one wire bus, though I suspect they are just using one. It connects to pin 14 or ATMEGA328. I don't think grim will release the source code. Not that he really cares, it's more someone using it to sell lookalikes.

Sorry have to dash...le tour highlights are on.
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  #88  
Old 16-07-2016, 02:34 PM
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Just realised RS USB connector is not good. Explain later, don't waste time looking into it.

edit: I am back, sorry about the cryptic message, I just didn't want you to waste any time on those connectors.
The RS connector has two parts. The actual plug is removable from the round housing - it is just a push-fit and it is not sealed. The waterproof rating applies only if a cap is used, or a matching connector is connected into the USB plug. The matching connector has a housing which screws onto this connector's housing. So, unless we want to keep the matching connector connected at all times, i.e. have a long cable going from the camera at all times, the plug is not good.

The Altronics connector is filled with epoxy and has pins coming out on the other side. A bit more soldering but it should be OK to use.

Last edited by luka; 16-07-2016 at 04:34 PM.
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  #89  
Old 16-07-2016, 04:47 PM
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Looking at some hybrid D sub connectors at RS atm. They would be good to carry power and signals. I don't think they have any sealing rating though as you select an insert the power pins you want. I'll look at digikey some more.

edit:
also looking at sealed (IP68) USB connectors element14...but they all appear to have rather large mounting diameters, like the Altronics version. We would have trouble with the case size and the connector size.

Last edited by wasyoungonce; 16-07-2016 at 05:17 PM.
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  #90  
Old 16-07-2016, 05:27 PM
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I think that the RS connector had similar size as the element14 and Altronics. I may even have them all here.

Question, how many connectors do we actually need to go into the box? USB + just one voltage (and GND)? Is everything powered from this voltage internally?

Edit: What I meant is that if PWM for the Peltier is generated inside then I don't see any issue passing USB + voltage through the same plug.
Something like this or this may be suitable.
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  #91  
Old 16-07-2016, 06:00 PM
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Or we just get any connector, solder wires to it and mount it and then put a big blob of silicone on it (from inside) to seal it
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  #92  
Old 16-07-2016, 06:06 PM
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Quote:
Originally Posted by luka View Post
Question, how many connectors do we actually need to go into the box? USB + just one voltage (and GND)? Is everything powered from this voltage internally?

Edit: What I meant is that if PWM for the Peltier is generated inside then I don't see any issue passing USB + voltage through the same plug.
Something like this or this may be suitable.
We need a separate +12V for the peltier. PWM puts a lot of noise on the power line and grim has allowed for this (separate +ve). Reality...it should also be separate gnd as well.

The Altronics IP68 connector looks good. Yep of stuff I'm looking at and also in D sub. I looked for sealed USB....nothing available. USB was never intended for this. Probably why FADDY made a breakout for all this. Actually his last images, page 84 look, good. Hi Cam85m is obviously working well.
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  #93  
Old 16-07-2016, 09:36 PM
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Brendan, I was just looking at the circuit diagrams and the Gerber files for Cam86 and, unless I am mistaken, 12V and Peltier+ are joined by a track in the copper top layer. Can you please check this.

Also, (I know we are not using it but...) the element14 USB connector is not sealed unless you put a cap on. They are the same as the RS ones. This is not obvious from the datasheet but the seal is only achieved by the outside o-ring. There is a sentence there saying "dust and waterproof sealing when mated". We use them at work. The connector itself can be popped out from the housing with a bit of pressure from the back. It makes it easy to replace when they get full of dirt.

I did lots of searching for a sealed USB connector that is smaller than the Altronics one over the past few years and didn't manage to find anything. If you do please let me know.

By the way, Altronics has lots of sealed D-sub connectors. Just search for "waterproof".


Back to Faddy's design, did he just poke the wires through a hole in a camera housing into a breakout box? I suppose that could be a way to go
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  #94  
Old 17-07-2016, 09:21 AM
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Just noticed I have the Peltier power rail wrong. Yes on the PCB image they are indeed joined. Sorry missed by ...that much!

Faddy made a hole in his case rear and sealed this with something that looked like silastic. These wires then ran to his breakout/peltier control box. It depends upon the material used. Something like a metal set like JB weld/Devcon would be ok but I suspect they wouldn't stick to some wire insulation.

The Altronics sealed D subs look just like the digikey versions or copies there of. I'd like to see their data sheet on them.
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  #95  
Old 17-07-2016, 10:06 AM
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I meant to link this before, Martin Raabe.

A German guy who built his own ICX453 camera, quite awhile ago, ~2010. Obviously is very talented, doing his own firmware, machining, design even its own inbuilt control and CF card etc. He obviously also paid attention to the sensor sealing.

He also built his own scope, autoguiders, stand alone autoguider, telescope mount and goto controller.

Pity he hasn't released any details.

Also of note is the way he had a secondary chamber around the sensor and desiccant system. Which I have been thinking about. From the RS images and data sheets, it's not entirely obvious that we can access the desiccant or remove the desiccant plug externally, without camera disassembly. It looks as if the plug seals with a nut and O ring but its not obvious if we can remove the desiccant without undoing it's housing. Thus we may not be able to purge our camera. Am I missing something here?

Brendan
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  #96  
Old 17-07-2016, 10:30 AM
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Quote:
Originally Posted by wasyoungonce View Post
I meant to link this before, Martin Raabe.

A German guy who built his own ICX453 camera, quite awhile ago, ~2010. Obviously is very talented, doing his own firmware, machining, design even its own inbuilt control and CF card etc. He obviously also paid attention to the sensor sealing.

He also built his own scope, autoguiders, stand alone autoguider, telescope mount and goto controller.

Pity he hasn't released any details.

Also of note is the way he had a secondary chamber around the sensor and desiccant system. Which I have been thinking about. From the RS images and data sheets, it's not entirely obvious that we can access the desiccant or remove the desiccant plug externally, without camera disassembly. It looks as if the plug seals with a nut and O ring but its not obvious if we can remove the desiccant without undoing it's housing. Thus we may not be able to purge our camera. Am I missing something here?

Brendan
Brendan why not put the dessicant on a plug that inserts into the housing, screws in and seals with the O ring. Several commerical cameras use this method. You can always charge the interior with Argon before you insert the plug, assuming you have it properly sealed. The new ASI1600 cooled cameras, have a top sensor cover section that unscrews from the rest of the case, exposing the desicant pill holders (4) underneath the cap; simple to change. I am sure you guys can come up with a solution.
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  #97  
Old 17-07-2016, 11:58 AM
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JThe Altronics sealed D subs look just like the digikey versions or copies there of. I'd like to see their data sheet on them.
Brendan, if you open the Altronics page with a D-sub connector of interest, say for example this one, you can click on specifications to get to a mechanical drawings. Also, to the left just above the image of the connectors it says "Amphenol LTW SDB-09PFFP-SL8001". That is the original manufacturer and the part number. This is not what Altronics usually does, only for some more industrial parts.

Glen, we are looking at commercial screw-in silica gel holders. However, the one we found here is VERY bulky. If you know of a smaller one it would be wonderful!!!

Brendan, the RS silica gel holder has a nut and o-ring. The way to do the mounting would be to screw it in properly and then use epoxy or some other strong glue to glue the nut to the box from the inside. Just have to be careful not to get the glue on the thread

However, the size of it is still a problem for the sealed chamber around the sensor. We could drop the idea of having a separate chamber for the sensor only and dehumidify the whole box. Or we could redesign the 3D printed part that the sensor sits on (see Faddy's images) and enlarge the chamber so it can have silica gel insert on a side... somehow...
As Glen suggested, we may have to make our own smaller insert, the RS one is too large.
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  #98  
Old 17-07-2016, 12:01 PM
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Brendan why not put the dessicant on a plug that inserts into the housing, screws in and seals with the O ring. ....

Yep spot on. The desiccant carriers we were looking at have an "O" ring and nut that would sit inside the housing, thus when undone the nut comes loose nor can it be taken out to "charge".

Which means its not suitable and yes I've been looking at other camera set-ups just like you mention. You can actually buy some of these plugs from camera mfgrs.

We would need to ensure the housing is threaded for this...but the housing walls are a little "thin". Maybe glue in place a doubler?
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  #99  
Old 17-07-2016, 12:29 PM
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Thanks for the info Luka. They did look the same as the Amphenol. IMHO the DSUB 9 pin might be best connector. Put it down the base of the case. Looking at the DB9 drawing and G106 drawing, there should be just enough room (edit...maybe not the G106 will need serious machining). Probably more if we use the Jaycar case. (Edit: might be better on the case lid at bottom. This way we could use a female to plug in a small power/gender box to hold a small PCB for USB/Power plugs)

The way the PCB is laid out should allow room for this as well even enough to put the connector on the case rear down the bottom.

Some desiccant plugs: here; here; here; here;

Gary is asking how many camera cases we want. Send him an email.

edit:
oh it would be easier if the D sub was male pins with solder cups...just easier to solder wires into. Some of the D subs have long pins coming out the rear which may interfere with the PCB, or we can cut them down, but soldering to a pin is more problematic than a cup.

Last edited by wasyoungonce; 17-07-2016 at 01:00 PM.
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  #100  
Old 17-07-2016, 03:01 PM
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Agree, solder cups at the back would definitely be easier to solder to than pins.

(If you were looking at the connector I sent a link to before, I just picked a random one to show you the part number on the top. I did not mean to imply that we should use either male or female connector)
Normally when building stuff like this I would use a female connector on the cable as it carries power and it is more difficult to short compared to pin connector.

Off-topic question, have you "freed" your sensor from the aluminium holder yet? I just noticed on Martin Raabe's page (your link few posts up) that he machined the aluminium to get the sensor out.
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