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Power and Data Box


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I have been busy again ( I just can't stay away from the shed :))

This time it's a Power and Data Box for my telescope. It will be mounted on the pier once I have an obsy. Until then I'll just hang it from the eyepiece tray under the tripod.

Features:

Output:

- 10x USB in 2 5x USB groups

- 6x 12V socket

- 4x 5V socket

- 2 channel PWM dew heater controller

- 1 serial port (USB to serial adapter)

Input:

- kettle style mains socket

- 2x USB-B socket

The heart of the box is a 12Volt 20A switched power supply. It powers the 6x 12V sockets, the dew heaters and a 12V to 5V 5A voltage regulator. That 5V regulator powers the 2 USB hubs, the 4x 5V sockets and the fan.

There are 2 completely separate (apart from the power supply) 7 port USB hubs with separate input sockets. I have kept this separate in case I ever needed to connect 2 PCs (one guiding, one imaging for example). I hope the common power supply does not pose a problem.

This shall be sufficient for the forseeable future. :eek:

The only thing I know I forgot is a 7.4V power supply for the EOS 1000D. I'll add that.

Here is the finished product:

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And this is what it looks like inside:

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This took me 18 hours to build (without planning) ;-)

As usual, more pictures of the build in progress here:

https://picasaweb.google.com/chris.yesyes/201107TelescopePowerAndDataBox#

Edited by yesyes
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Hi Steve, I'm sure you know already but with the Startech hub you have to set internal jumpers to control how the hub supplies power to the USB outlets. This is taken from the 'reviews' of the un

I have three of those StarTech hubs - one of them slightly broke. They are tough to break but my mount cover leaked some time ago and let water through, this literally filled the hub with water! I onl

Hi Steve, I can't say anything against this PSU. It's been in there for many years now and has never given me any problems. I'm using a few more of these around the house and observatory; one for

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Nice Workmanship! As a matter of interest, what are those "Off-Centre" power sockets? :)

(Having "standardised" on XLR sockets (plugs), still not entirely enamoured...)

Edited by Macavity
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Thanks for the nice comments... ;-)

Nice Workmanship! As a matter of interest, what are those "Off-Centre" power sockets? :)

These sockets are these ones:

eBay - The UK's Online Marketplace

I chose them for 2 reasons:

- they have a long thread so allow for more panel thickness

- they have the thread at the back making them look nicer from the outside

Also, the plastic doesn't melt immediately when you approach them with a soldering iron. :eek:

Oh, and at just over £3 for 10 pieces the price is right too. Delivery from China does take about 2 weeks though.

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A very neat job indeed!

One quick comment if I may, I assume the lid will go on to enclose it all? If so, will you need any vents cutting to draw cool air in for the fan to exhaust the hot air from the psu and regulators?

Don't want you to have any meltdown after all that hard work.

Ian

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I was hoping someone would ask .. :)

The fan blows cold air in from the bottom. The gaps between the USB ports should be large enough for the warm air to be pushed out. So cold air in from the bottom left and warm air out at the top right. I'm hoping this roughly diagonal air flow would be enough.

The fan is a 12V fan running at 5V so it's rather quiet. It has been recommended here in another thread that the fan blows inwards because that makes it easier to install an air filter if dust becomes a problem. If teh fan sucks the warm air out, you have no control over where the dusty cold air gets in.

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This is a great job, now if I were to ask you to build one for me say, how much would it cost, hope you don't mind me asking, not very good with my hand's and this could help.

The materials alone came to about £110. I didn't realise just how much until I added it up a minute ago. It silently adds up when you buy bit by bit...

And it took me 18 hours to build (at a leisurely speed in my own time). I'm not sure I'd want to do that again... ;-)

But more importantly, I'm not a qualified electrician. So I wouldn't take the risk of building anything involving mains electricity for someone else.

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But more importantly, I'm not a qualified electrician. So I wouldn't take the risk of building anything involving mains electricity for someone else.

It would also leave you open to prosecution from trading standards as to sell anything electrical in the E.U. requires it to be CE marked, and to do that means ££££ worth of testing.

I keep reptiles and also have an interest in electronics, and around 18 months ago started a project to build a 4 channel pulse proportional thermostat with control for lights etc. The prototype of which is shown below

MK2%20front.jpg

MK2%20back.jpg

There was so many requests from other members of a forum that followed my progress on a build thread that I had a small batch of PCB's made, and was then informed of the regulations, especially with mains powered devices. Not having the £10K to get them through testing and marked with the CE so I could sell them I opted to refuse requests to make them for other members.

Whilst I'm confident that the units are safe (my prototype has been keeping my two Royal Pythons at 36c for the past 14 months and never had an issue), with the common practice to sue anyone over anything I wasn't prepared to take the risk of selling a unit to someone else.

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Very nice - 18 hours without planning, any less if you had planned :)

Only joking. Really nice set-up. I don't have anything as elaborate and mine sits under my mount, but I worry if there is any hot air turbulence from the fans that could distort images...

Francis

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It would also leave you open to prosecution from trading standards as to sell anything electrical in the E.U. requires it to be CE marked, and to do that means ££££ worth of testing.

I keep reptiles and also have an interest in electronics, and around 18 months ago started a project to build a 4 channel pulse proportional thermostat with control for lights etc. The prototype of which is shown below

There was so many requests from other members of a forum that followed my progress on a build thread that I had a small batch of PCB's made, and was then informed of the regulations, especially with mains powered devices. Not having the £10K to get them through testing and marked with the CE so I could sell them I opted to refuse requests to make them for other members.

Thanks Malcom. I didn't know it was against the law. Do you know where to find these regulations? What about low voltage stuff (12V or less)?

Your controller looks really professional. :)

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Very nice build. The only thing I don't see is any fuses? I would have put a few fuses on the outputs.

Fuses are for sissies... :)

The 12V power supply is pretty well protected on the output side (or so they say). I'll put a lower fuse in the mains plug and I will never run it without an RCD in the mains feed. So the mains side should be fine too.

Also, the whole thing is over engineered. I don't think I'll ever get anywhere near 20A output.

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Very nice - 18 hours without planning, any less if you had planned :)

Francis

hehehe, I think that came out wrong. ;-)

18 hours building plus time planning what I need, comparing prices, ordering, ....

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Thanks Malcom. I didn't know it was against the law. Do you know where to find these regulations? What about low voltage stuff (12V or less)?

I've since deleted most of the bookmarks, but googling CE Mark directives should throw up some results. From memory there were three directives, LV (below 50v dc), mains voltage, and radio interference which basically covers anything that switches voltage either in the process of voltage regulation or when manually activated (like turning it on!). As your unit has a main feed, uses a PSU (presumably switching), and has 12v outputs my guess is that it too would need to comply with the same three directives.

The thing is that it's not actually against the law for you or I to sell one of our projects to someone else, as technically the law only applies to businesses, and not private individual. However in a telephone conversation with local trading standards the officer said that whilst the risks would have been made clear to the purchaser, if something drastic happened such as a house fire or electrical shock the purchaser could take the seller to court and it would be down to the Judge how to interpret the guidelines. She did site some test cases but stated that to her knowledge theses were very fare and few. One factor is the definition of "business" as selling a single unit for profit (even to cover building time) could be deemed as trading... If found guilty of breaching the directives the fines are tens of thousands or even imprisonment. Basically it's such a mind field its simply wasn't worth the hassle for me to pursue, and I wasn't prepared to take the risk, especially as my unit could be switching up to 2KW of heaters

Your controller looks really professional. :)

Thank you...

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excellent job.. and coming to this late.

You can see why so much stuff is made with low voltage supply inputs relying on bought in PSUs, you lose so many CE requirements that way.

Re the fan.. do you have a filter on it or just a finger guard?

Derek

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Re the fan.. do you have a filter on it or just a finger guard?

Derek

For now it's just a finger guard. But I was remembering your advice about the air filter and had that in mind when I placed the fan. If dust becomes an issue, I can add a frame / air filter holder on the outside. I also made the fan blow inwards thanks to your advice.. ;-)

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I made a few improvements to the box last night.

I changed the USB to serial adapter. The one I used initially turned out to be one of these that have a "fake" PL-2303 chip that doesn't work on Win 7 x64. (See this post for more details). The adapter I'm using now has a real PL-2303HX chip and a level shifter chip for proper RS232 signal levels.

I also integrated my power supply for my EOS 1000D camera into the box:

IMG_4777.JPG

I used a 6.3mm mono audio plug / socket in order to avoid using the wrong socket by mistake and potentially damaging the camera.

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I also added a few more wires between the PSU and the 12Volt "distribution board". The 2 wires I had would have never been able to cope with 20 Amps. ;-)

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So now the inside looks like this:

IMG_4770.JPG

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