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Quick weatherproof camera box.

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Offline Microfunguy

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Re: Quick weatherproof camera box.
« Reply #90 on: 09 / September / 2013, 20:06:47 »
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Quote from: ahull on 09 / September / 2013, 12:20:54
Any pictures of the surgical procedure?

I was going to but never got around to it.
I can describe the key points for the SX220hs.

First of all, the camera interior is packed so tight that there is virtually nowhere to fit a socket.
The only options, that were not easy, was the middle of the front top and very near the lens as in the above photo.

That was so tight that the holes had to be drilled to within 0.5mm of the desired location.
As the body was metal, I started with a 0.5mm drill and gradually worked up to 1.8mm.
The  socket strip pins were inserted into the holes and a tiny blob of cyanoacrylate applied from the other side using a needle, carefully checking the pins did not touch the metal.
That was verifield using a multimeter and tiny blobs of just-mixed 5-minute epoxy applied with a needle and allowed to flow into the hole around the pins.
After four minutes the now less viscid epoxy was applied all around the pins and built up into a little block.
After one hour, extremely thin wire (as used for indoor flying) was soldered to the pins and run in a shallow groove to the top of the case and secured with a blob of glue.
By holding the case front (with the socket) inverted and upright against the camera body, the trimmed wires were just long enough to reach the pcb tracks connected to the battery springy contacts.
The front could then be folded down and with difficulty pushed over the body.
Quite simply, if there had been excess wire or you had used the thinnest wire commonly available, you would not be able to mate the two parts.
The back of the camera was then fitted.

The Pololu worked with short leads but when I tried them just now with very long supply leads the camera turns off just after starting to extend the lens.
In such situations Pololu state you are meant to fit a capacitor of 33uF or more across the supply pins.

I will try that later.
« Last Edit: 09 / September / 2013, 20:08:33 by Microfunguy »
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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #91 on: 10 / September / 2013, 05:23:26 »
Quote from: Microfunguy on 09 / September / 2013, 20:06:47
The Pololu worked with short leads but when I tried them just now with very long supply leads the camera turns off just after starting to extend the lens.
In such situations Pololu state you are meant to fit a capacitor of 33uF or more across the supply pins.

I will try that later.

This may be stating the obvious, but I would keep the regulator as close to the camera as possible, and make the feed wires to the regulator long, rather than having long feed wires *from* the regulator. If the input voltage to the regulator drops slightly as a result of the long wires,  so long as the drop is not too much for the regulator to deal with, then this is obviously far less of a problem than if the output voltage from the regulator drops for this reason.

The 33uF cap (or indeed a much larger one, say 470uF)  may well help, if the issue is due to slight brownout due to short periods of high current demand (for example extending the lens), the cap will help smooth these dips out, but if the issue is due to the resistance of the wires from the regulator, it might make little difference.
« Last Edit: 10 / September / 2013, 05:28:48 by ahull »
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Offline Microfunguy

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Re: Quick weatherproof camera box.
« Reply #92 on: 10 / September / 2013, 06:14:14 »
No, I have already tested with 300mm length of wires on regulator output and that is fine with short wires from the battery.

Even with the capacitor, the camera still turns off.
The 1500mm supply cable is rather thin, I will try something else.
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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #93 on: 10 / September / 2013, 09:21:50 »
I would need to scope the pins on the camera end of the cable to know for sure what is happening, but I suspect you are correct, thin wire would give more loss. A Cat5 cable pair would be around the minimum gauge I would trust at that length. We are talking about the camera drawing around 2A for the lens move, so roughly speaking anything thinner than 2A fuse wire will probably pop (or at least heat up, and in the process cause significant losses).
« Last Edit: 10 / September / 2013, 09:45:30 by ahull »
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Offline Microfunguy

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Re: Quick weatherproof camera box.
« Reply #94 on: 10 / September / 2013, 12:16:17 »
I have used thicker wire on the supply side and that is OK.
The previous cable resistance was 0.7R.

As I am using a 6V battery, when the supply voltage drops you get into the region where it sources less current.

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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #95 on: 10 / September / 2013, 19:23:54 »
2A through 0.7 Ohms looses a lot of power relatively speaking P(W)=I^2R so far as I recall, so you are loosing 2^2*0.7 = 2.8 Watts in the wire. That should warm it up nicely, and the 0.7 Ohms should also work as a pretty effective voltage divider   :P  No wonder it was struggling.
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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #96 on: 11 / September / 2013, 15:36:05 »
Still no mosfets, so being an impatient chap I decided to start hacking my Ikea Lottorp alarm clock ...

"Ikea Lottorp"

...without the mosfets. It seems I'm not the first person to dismantle one, here is another version of the same clock, ripped apart and put back together.

The idea is to take the alarm signal and use it to wake up the camera every day at a specific time. After it wakes up, the camera can decide what it wants to do next. Sleep till exactly X minutes before calculated local sunrise would be the sort of thing I was thinking of, or set the alarm to  just before dusk to switch on the camera and try to catch the Owl on the fence post with motion detection, then have the camera switch itself off again when it becomes too dark for it to take a decent picture. Any other idea that needs to wake the camera at specified time would be a candidate. This particular clock has a count down timer too, I might investigate using that for repeated wake-ups, say every hour.

My particular variant of Lottrop was in the pile-em high, sell-em cheap bins at one of our local Swedish sell anything retailer a couple of years back, and is obviously a cheaper iteration of the design seen in the link I just mentioned.

Mine is simpler in construction, lacking the fancy bezel and the coloured LED.  It only cost £1, so naturally I couldn't resit, and bought two. This is at least part of the reason why the head of Ikea is a multi-millionaire and I am not.

The idea is simple and has been done 1000 times before, take the "beep" output and use it to switch something else on.

In this case I was planning to rectify and smooth the beep and use that to charge a capacitor/resistor pulse extender, and use this to drive a mosfet to switch on "Gold Solar Battery Charger 2600mAh" and/or any other battery pack. Not an arduino in site so far you will notice.  ;)

So first on the agenda, rip it to bits and see what makes it tick  :P Pictures of the gubbins inside are in the usual place...



It turns out this may be easier than I expected, inside is a simple single sided board with solder pads that a human being with a normal soldering iron can attack.  There is even a discreet transistor to drive the beeper.


This is roughly the idea. Q1 is the existing buzzer transistor. I fired my scope on it and the base is fed a square wave of about 1kHz. I will rectify and smooth this with a view to switching on an N-Channel mosfet (and thus the battery or solar charger) with the DC Alarm Out signal which should be a pretty rough but elongated pulse.

I wired 3 strands of ribbon cable, one from the base of the transistor, and one each from 0V and +3v from the 2xAAA cells that power the clock. These two batteries typically last over a year, more than enough for this project.
« Last Edit: 12 / September / 2013, 15:46:23 by ahull »
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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #97 on: 12 / September / 2013, 07:07:37 »
This idea would work with pretty much any alarm clock, or even a digital watch module, so long as the mosfet you choose will switch with whatever voltage you can derive from the buzzer output. Most alarm clocks use a single AAA cell, so if you used on of these, you would need to be sure that your switching mosfet will work with such a low voltage. Bearing in mind the voltage drop of the diode, you may be left with as little as 0.8V from the pulse extender to switch on your mosfet, so you may need to use some additional trickery to get the desired result.

Values for the capacitor and resistor after the diode should be chosen to keep the mosfet on between beeps, and their values would need to be determined by experiment. The purpose of the resistor is to allow the charge in the capacitor to drain away and thus switch the mosfet back off within a reasonable time after the last beep from the alarm. One other thing to watch out for is that the chosen alarm clock or watch stops beeping after a few minutes (most do), otherwise the battery will be switched on forever after the alarm activates.

The circuitry in alarm clocks is obviously designed to give very long battery life, so it has a rather obvious advantage over using something like an arduino with an RTC module.
« Last Edit: 12 / September / 2013, 07:58:39 by ahull »
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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #98 on: 12 / September / 2013, 15:43:34 »
In case anybody ever wants to copy this idea, but is unsure if they can get hold of a suitable device to hack, it seems Ikea is not the only source of this particular alarm clock.



This ebay number looks remarkably similar, click here for details.
It has an identical display, the same functions and even has the slightly tacky colour changing LED  :D , so it would be worth risking a few bob to try it.

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Offline Microfunguy

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Re: Quick weatherproof camera box.
« Reply #99 on: 12 / September / 2013, 15:59:45 »
1.97 GBP including shipping from China !

China will rule the World in the relatively near future.
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