Yet another camera rehousing

[Dave_D]

Thought I'd start a new thread instead of hijacking someone elses.

Now I figured out why the camera wasn't starting up after I stripped it, the rebuild is under way.

looking quite good if i say so myself

still got parts to arrive yet then i can wire in the arduino, camera power and peltier. Nedd to fit a thin rubber layer between the front casing and the coma corrector for a good tight fit when i remove the CC spacer.

The heatsink is out of an old dead nVidia 8800gt i had sat in my spares box. There's enough clearance with the peltier and coldfinger in place. just have to fashion a fan holder. (may be a good excuse to get in touch with the local 'maker' centre...

[madjock72]

what you planning on doing with the arduino Dave. Going to my local maker next week, need some info on stepper motors.

[Dave_D]

the arduino will be controlling the peltier cooler and associated sensors. the back panel has a 20x4 lcd display for output.

this vid shows the lcd on the back panel

http://vidmg.photobucket.com/albums/v369/vanityassassin/VID_20160601_194525_zpsre9jjapu.mp4 

the focuser i built uses a 12V 4-phase 5-wire Geared Stepper Motor (28BYJ-48-12V) and a ULN2003 4-phase 5-wire Arduino Stepper Motor Driver module Driver board (LL4B301) both standard items and easy to throw together (both are easy to find on fleabay)

[Gina]

Nice neat looking unit   I use the 28BYJ-48-12V and ULN2003 for my focusers too driven from Arduino Nanos.

[Dave_D]

Question about fitting the cold finger...

the three screws (with red dots) hold the sensor in place. would it work using longer screws and drilling three holes in the cold finger in these locations to screw the cold finger down and hold it in place. i've ground down the two location studs (green dots) flush with the sensor plate so either way, the cold finger is flush.

[Dave_D]

bought some 2mm Black Smooth ABS Sheet off fleabay... makes excellent inserts for the box. printed off a template in my cad software and cut out with a stanley knife. fits like a glove

the electronics will be housed in this partition. don't really need to isolate them from the camera but it provides a good surface to mount the circuit boards and has the added benefit of letting me remove all the  electronics in one go. just need to make pass-through holes for cabling.

 

[Jokehoba]

On 13/06/2016 at 22:09, Dave_D said:

Question about fitting the cold finger...

the three screws (with red dots) hold the sensor in place. would it work using longer screws and drilling three holes in the cold finger in these locations to screw the cold finger down and hold it in place. i've ground down the two location studs (green dots) flush with the sensor plate so either way, the cold finger is flush.

On my 1100D mod I made sure that the cold-finger was only in contact with the back of the sensor. All other contact zones were insulated to prevent any chance of condensation on the electronics.

Screwing it in place will certainly earth the cold-finger to the camera but builds a thermal/electrical bridge to the sensor support frame. Would this not lead to an increased risk of condensation and less efficient cooling?

John

[Gina]

I think it could.  I have cold finger well thermally insulated from everything except back of sensor and Peltier TEC.

[Dave_D]

ahhh yes, i see... so just drilling the coldfinger with large enough holes to clear the three screws to allow the coldfinger to sit flush against the sensor is a better method?

[Dave_D]

Cold finger rough cut ready for cleaning up and bending to the final shape. Larger section provides full contact for the peltier i'm using.

[russellhq]

Hi Dave, here's how I tackled the cold finger design for my 1100D:

https://stargazerslounge.com/topic/209720-canon-1100d-cold-finger-peltier-cooling-wip/?do=findComment&comment=2321254

I never screwed mine down. I found the plastic shim gave enough resistance to hold it in place.

[Dave_D]

Board design Mk I

nerdiness is running high

This designspark pcb is really good fun lololol

[Dave_D]

Anyone with greater (much greater) knowledge of circuit design see aanything glaringly wrong so far on this schematic?

not done the 12v side yet though.

[ringz]

The only thing I can see is really just the fact that you have added +5v and Gnd to each inverter when in reality you only have to do it once on the physical chip. If you make a PCB for this it might have an impact on the routing if the software isn't clever enough to notice.

 

[Dave_D]

yeah it looks that way but when the pcb is generated, only 1 5v and ground are created... this designspark is pretty damn clever

currently trying to find a schematic for a non-pwm peltier driver... heard that banding can be an issue.

i've also gone with resistor arrays for the RC inputs to the inverters. hope this works ok. the power requirement for each input is quite small and the resistor arrays have a total of 1.25-1.4w according to the specs of the parts i've found.

[Dave_D]

 

1st prototype of the hardware debouncer bypumping a cheapo KY-040 rotary encoder through a 74HC14 inverting schmitt trigger.... works so much better than software debouncing...

Encoder Position: -1
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Encoder Position: 3
Encoder Position: 2
Encoder Position: 1
Encoder Position: 0

silky smooth...
 

[hughgilhespie]

Hi Dave,

Coming late to this and I  definitely fail your stress test "Anyone with greater (much greater) knowledge of circuit design" but one possible thing is that you have used the Nano D0 and D1 pins as inputs. As I'm sure you know, these are used during programming so anything hanging off them MAY prevent uploading. I always leave the pins alone, plenty of others are available.

Regards, Hugh

PS Another vote for hardware debouncing!!!

[Dave_D]

On 30/07/2016 at 10:09, hughgilhespie said:

Hi Dave,

Coming late to this and I  definitely fail your stress test "Anyone with greater (much greater) knowledge of circuit design" but one possible thing is that you have used the Nano D0 and D1 pins as inputs. As I'm sure you know, these are used during programming so anything hanging off them MAY prevent uploading. I always leave the pins alone, plenty of others are available.

Regards, Hugh

PS Another vote for hardware debouncing!!!

 

true on d0 and d1. Ive been using a full arduino nano so i can program it by usb so it isnt an issue. I just got an ATMEGA  and crystal for the completed project. Gonna build a programming board like i mentioned in another thread... like i need a good excuse to make more stuff

[Mick J]

Good work Dave,  just found this thread - looking forward to seeing the finished article.