Introduction and Question

[allanuk]

Hi, I am Allan from Hampshire. I am an amateur astronomer and solar observer, but with a preference for near real time observing using video cameras. I generally observe meteor showers visually, but have recently changed to video observing and capture as I can do it any night the sky is clear.

I am installing a better video meteor capture system up on my roof. It will be a 2 camera system controlled by a dusk till dawn photocell as in the link.

 www.neweysonline.co.uk/newlec-photocell-cell-kit-105-lux-switch-off/1000015760/ProductInformation.raction

I have installed the first camera in its housing and mounted it on its pole and connected all the electrics. All working fine except for the photocell??

I have checked the wiring and can find nothing wrong.

Basically, the power from the 12v supply goes to the photocell and then to the camera. As you will all know, the camera should turn off at dawn, but my camera is on all the time, even in bright sunlight.

Reading the specs for the photocell, it states the power supply as being 198-264v ac. I am only using 12v.

As the photocell switch is operated by lux levels, I would not have thought the voltage used would make any difference. Have I got a duff unit, wrong unit, or am I misunderstanding something.

Regards

Allan. 

[BillW]

Hi Allan,

Firstly, welcome aboard!

There was a similar thread a while back about some automatic switches. You need to be really careful when dealing with mains voltages. I had a look at the unit and it appears to be for switching on security lights and the like. So it needs mains power to run and when it switches on it sends mains to the external item to be powered.

There isn't a wiring diagram so I don't know how it works for sure.

If you've connected 12 volts to where mains is supposed to be connected it will not work. Depending on how the thing is wired internally this may have damaged it already.
However DO NOT connect it to the mains and have the output go directly to the camera. If it is switching mains voltages you will certainly destroy the camera!

I bought a similar unit from B+Q a while back. It works on what appears to be the same principle. The unit had a small sensor which detected the light. After it was plugged in, when the light faded to a set limit the thing would switch the mains through it. (This was made specifically for turning mains powered lights on and off.)I had this connected to a mains to 13.8V power supply which would then power the camera. I ditched it as it needed a bright light level to switch it off, basically the sun had to be up.

Now, if this is broadly how it is working, how are you currently getting 12v to the camera through the thing? That intrigues me...!

Is/was there a paper circuit diagram you could copy and post. That might give us a clue as to what is really going on.

However if you are unsure consult an electrician! You don't want to kill yourself let alone the kit!

cheers,
Bill.

[allanuk]

Thanks for the reply Bill. If you can tell me how to upload a pic, I can post a pic of the simple diagram to show how its wired. I am not using any mains voltage except to plug in the 12v transformer supplied with the cam. It is strange that the power is running straight through the photocell in sunshine.

One other prob has arisen. When I acquired my housings, one of them had a 24v ac transformer inside. This appeared to provide power for the heater and camera. I used this 24v transformer to power the heater only, but within 30secs I had a pure white patch appearing in the bottom left corner of the image. I unplugged it and the white patch faded. I can only assume that it is somehow creating heat in the camera and causing what appears like extreme amp glow at one corner of the sensor. I tested my other housing, and yes the heater gets quite hot, but its nowhere near the camera. The heater is right at the front under the lens.

Apart from teething troubles the cam is working fine.

[allanuk]

This may work.

photocell.bmp (50.56 KB)

The only difference is that I am only using a 12v supply.

 

[BillW]

Hi,

You've either been lucky or very lucky! The unit is what I described, used for switching an outside light on/off at dusk/dawn. The B+Q one is wired the same way.
You're probably getting DC through a route it's not supposed to (if it's not killed the camera that's the lucky bit) and if you had indeed connected it to your camera with mains it would have vapourised it (that's the very lucky bit).
Do not connect your camera to this at all. This sensor is for mains voltages only.
From your comments about the heater it sounds as if you have a leakage current problem too.
Other than I can't offer any more advice as I'd need to see it and get my meter onto it. Is there anyone you know, maybe in your local astro soc, that has some experience with electrics.
This needs to be handled with care so as not to do any damage.

cheers,
Bill.

[allanuk]

Thanks Bill, having done a bit of research it does indeed seem that I have bought the wrong photocell. I will get a 12v photocell and fit it into a waterproof housing. I'll disconnect the other photocell and just power the camera direct. As its dark when I get up in the morning and dark when I get home, I will just have to switch the cam on manually for the time being.
I've disconnected the heater until I find the problem.

Still, looking on the bright side, I have one cam set up for the Orionids tomorrow if the sky clears and dew doesn't become a problem.

[BillW]

Hi,
Good stuff. I've found that wrapping the camera and lens in a loose layer of bubble wrap helps.
The camera body's do warm slightly in during operation, the heat tends to be funneled up the length of the camera and lens underneath the bubblewrap.
This in turn helps prevent dew forming for a while.

I don't think I'll see much of the Orionids, the weather here was wild last night and the forecast is grim.

Cheers,
Bill.

[allanuk]

The camera is inside a saeled cctv housing Bill, so I don't think wrapping the cam in bubble wrap would serve any purpose. Its just the optical window I need to keep clear. Forecast down south is uncertain. Windy today, but may clear late tonight. Fingers crossed.

Its actually too windy to go up on the roof to install the second camera.

[stewartw]

Hi Allan,

Welcome aboard ... sounds like you've already resolved the photocell issue - the recommnedation to go for a 12V DC version (as opposed to the 230V AC model) is the safest option. It is possible to get the latter to work but it won't be as elegant.

If the CCTV housing is sealed (and you're confident there are no leaks (either water or moist air) then a couple of bags of desiccant should do the trick and remove moisture from within the housing. There are multiple online desiccant vendors (eg eBay).

Windy here too her ein Cheshire with very little propsect of clear skies for the Orionids

Best regards

William

[allanuk]

Hi Stewart, I checked the manufacturers spec on the housing and it is a 24V ac model, so the heater inside should work at 24v. Somehow it was creating a white out at one corner of the frame, so maybe it is faulty. I won't use the heater until I have tested it properly. The heater will actually work at 12V albeit a bit cooler.

Good idea with the desiccant bags.

Still howling here, but plenty of blue patches.

[allanuk]

Still at work at 9pm and crystal clear here. In fact I stood out on a playing field and there are so many stars visible, I find it hard to navigate. Can't wait to get home and fire the camera up.