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PostPosted: Sat Apr 18, 2015 7:42 pm 
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The heater appears to be attached firmly to the Bi metal strip, it's the wire which has come loose, I tried to solder it back on but I'm not getting enough heat into it to melt the solder. I only have a 25w soldering iron! I will let you know how my Engineer gets on with the silver solder.

After looking through the Horstmann T20 cells I noticed that some of them have two heaters for some reason.

The majority of the Zodion ones I have are Electronic. No nice click when they switch on!

Regards,

Andrew.


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PostPosted: Sat Apr 18, 2015 8:35 pm 
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Interesting picture, didn't realise they had 2 heaters. A 25W iron should be sufficient, it may be difficult though to get the new solder to flow onto the old joint.

No wonder the mechanism was simplified as time went on - its very much an "engineers" internals in that one.


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PostPosted: Sat Apr 18, 2015 9:40 pm 
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I know it must have been expensive to manufacture.

I have just tested some SS55  zodion cells, one of them just made the lamp flicker when it was supposed to be off. I decided just to bin it, the build quality is very poor on the controllers and the base. The older stuff like the ss34 seemed to be better.

Regards,

Andrew.


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PostPosted: Sat Apr 18, 2015 9:55 pm 
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Here are the insides of a Horstmann type 705. It has 7/69 stamped on it so I assume it was manufactured in 1969. The heater on this one is quite large compared to the 'newer' ones.

The fault with this one is when the system is first energised the controller switches on. After a short while the output switches off but doesn't come back on in the dark. Even after a power cycle the output remains off. The contact 'stopper' has snapped internally as shown in the pictures allowing the bi metal strip to spring open fully and not return to the on state.

Regards,

Andrew.


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PostPosted: Sun Apr 19, 2015 7:24 am 
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You have highlighted another failure mechanism, especially for the RT thermals. There is a small spring strip in those which snaps the contact to make up for the gradual movement on the bi-metallic strip which would otherwise cause the contacts to arc.

When this fails, it prevents the bi-metallic strip moving too far, which in bright sunlight can cause the strip to bend to far and result in a day burn.


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PostPosted: Fri Apr 24, 2015 6:08 pm 
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Hi All,

After doing a few tests last week on my photo cells and controllers, I decided to build a testing station.

I was intending to have two little brackets made up to hold the photocells but they sit quite nicely on top of the controllers as can be seen from the photographs.

When the system is powered up the lights illuminate, after a short while the lights go out, then after another short delay the lights come back on again. This keeps cycling until the power is removed. If the lights don't go off or when off don't come back on again then there is a fault with either the controller or the cell or both!!

The zodion SS55 range behave very strangely, the switching cycle starts off normally then after a minute or so the switching on and off times get faster and faster until the light is flashing on and off?

Would any one know why this is?

Regards,

Andrew.


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PostPosted: Fri Apr 24, 2015 6:30 pm 
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Zodion photocells are very poor. Aside from the "flashing" you can see at switch on and switch off time, another variation is that at switch on time a Zodion photocell will switch on the lantern, then half or one minute later switch it off, then a minute later back on, then half a minute back off, and so on for a few cycles. Outside the front of my house two thirds of the Zodion-controlled lanterns repeatedly switch on and off at lighting up time.


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PostPosted: Fri Apr 24, 2015 7:12 pm 
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Zodion cells have very simple electronic circuits that lack hysteresis which results in flashing at the switch points. SELC and RT cells are far more advanced and the latter monitor several time periods to check each one is getting darker (or lighter). When they have (I think) 4 periods whereby each darkens or lightens, then they will switch.


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PostPosted: Fri May 01, 2015 7:44 pm 
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Hi,

You can see there isn't much to the newer Zodion cells on the circuit board. The older SS6s seemed to have a lot more components on board including some kind of op amp circuit.

Regards,

Andrew.


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PostPosted: Sat May 16, 2015 9:44 pm 
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Hi All,

I have just acquired a dimming photocell. It is a Zodion SS20. This is the first one in my collection.

Has anyone any experience with these?

Regards,

Andrew.


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