Christmas Holiday Project

[Stargazer33]

As I shall be off work for just over a week during Christmas I thought I should find myself a little project to stop me from going stir crazy!

I have been having a little trouble with my jump starter power pack recently and have been thinking about making a mains power adaptor. Therefore I thought this would be the perfect opportunity to build one. At the moment I am only worried about powering my CG5-GT mount and an anti-dew heater band, but I am including another two power outputs for future purchases! Each output will be independently fused in addition to a main case fuse.

This will all run through an RCD.

I am hopefully going to be getting all the parts from my local Maplins store on Saturday so that I can be sure to have them for the holiday.

My parts list consists of:

1x ABS Box MB4 (LH23A)

2x Panel Mount Power Socket 2.1mm (JK09K)

1x Switched IEC Chassis Socket (N94CZ)

2x Panel Fuseholder (GU73Q)

1x LED Toggle Switch Red (N26BJ)

1x Euro 3Pin Lead 5m Black (QZ82D)

1x CCTV 12Vdc Regulated 5 amp Switch-mode Power Supply (N63JN)

Plus 3 amp wire in red and black.

I'm going to add a 12v fan to draw out any heat that may build up in the case and put a couple of filters at the opposite side of the case to allow for air ingress. I will probably also add some feet to the bottom of the case just to keep it off of the floor & reduce any possible vibration noise from the fan.

Not including the wire it comes to £53.53. I could probably source some of the parts cheaper elsewhere, but I wanted all the bits ready for the holiday and I didn't want to have to rely on the post getting through in time.

If anyone sees any glaring problems or ommisions then please let me know.

I am intending on taking pictures during the build which I will post here for your delight and edification!

[JAS]

Sounds good Bryan,

I would consider a diferent PSU.

I am not sure about your mount, but I am using a HEQ5 and this requires about 12.6v to run properly, and is rated at 2 amps, most batteries used to power a mount will be outputing 12 - 13.5v. This psu, http://www.maplin.co...r-supply-589145 is a bit more money but you can regulate the output up to 13.2v.

When I made mine the output was set at 12v, I have had to turn it up to 12.8v to keep the mount happy.

I would also consider a higher amperage output to allow for any later aditions, your mount and dew heaters would probably take up the best part of 5 amps.

Take a look at the one I made here: http://stargazerslou...0625-mount-hub/.

Good luck

Jason.

[Stargazer33]

Hi Jason,

Thanks for the advice. I was looking at that power supply originally but wasn't too sure if it was overkill. I think my mount only draws 2 amps and my dew heater only draws 0.5 amp. I didn't really think about the voltage! I don't think my battery pack has ever been above 12.5 Volts even at full charge - I guess there-in lies the problem.

I liked the look of the CCTV power supply as it came with the mains power lead and a 4 way splitter that I was going to use to route the 12v to the dc sockets. I thought that as it was a regulated power supply it would give a constant 12v no matter what I connected to it and as I would only be drawing half of the potential 5 amps it would be well within tolerance. I guess it would be a shame to build this and then find out that it couldn't power the mount properly!

I think your power box is amazing by the way - very professional looking! I see you have USB ports like yesyes. Can I ask what these are used for? Are they used just as an alternative power socket or are they used as a hub to link multiple USB items into the laptop?

[JAS]

Both psu's supply 5 amps, I would look into the power requirments of your mount before spending any money, I can see the ease of using the CCTV supply, but as you said you dont want to build it and then find out it doesn't do the job. I thought the same and had a constant 12v, but I was wrong! The mount was working but the power LED was flashing when slewing because the voltage was to low, this also efected the guiding at times, more so as it got colder. There are also other things to consider like how long the wire to the mount is and the gauge of wire.

I know I would have been gutted if I wasnt able to turn up the power in mine.

I use the USB hub for PC mount control, DSLR/ webcam, guide camera, game pad for mount, and GPS dongle.

Jason.

[fwm891]

Good luck with the build - I hope your Maplin store is better supplied (for compnents) than mine... Ended up ordering online because so many bits were not stocked.

[Stargazer33]

Thanks Jason, looks like I'm going to have to delay the build slightly as the variable PSU is only available off the web and it is too late to get it delivered for the holiday.

Francis: I checked my local Maplin had all the bits through their on-line 'buy and collect' thingy. I had to reduce my dc socket and fuse holder counts as they only had 2 of each in store and I wanted 4 of each for future proofing. As I only need 2 to get me up and running I settled for that at the moment but I will mark up for the other two for later.

[JamesF]

Please do post pictures of your progress. This sort of project is always interesting to see.

James

[Stargazer33]

Slight change of plan and possible delay to build.

On Friday about half an hour before we were due to leave work for the Christmas break our boss called all the technicians into the office and put a problem to us. One of our customers has fallen down on an important delivery (which includes a financial penalty clause) so they have asked us to provide 200 units by the end of the year (I believe all their guys are having Christmas off!). That means us technicians going in over the Christmas holiday! It's one of those situations where you can say no, but you know it will count against you in the future if you do. Especially if you are the only one that says no!

So my build time has been considerably cut short.

On a positive note, whilst I was picking up the parts from Maplin on Saturday (the fuse holders were out of stock despite showing a positive stock level when I ordered) I noticed a different project box that I hadn't seen on the web site.

It's bigger and should be easier to drill for the sockets and switches etc. Also when I saw the size of the original box I had ordered it looked way too small. Especially if I want to expand later.

I went with my original power supply despite Jasons advice. As soon as I got the parts home I tested out the power supply on a fully laiden mount and it performed perfectly. It is also a cool running power supply so it looks like I may be able to do without the case fan.

I am also doing away with the LED tipped switch as it is just way too big. I have bought a couple of 6a on/off switches from Halfords that I have used before in my heater tape controller. I am now intending on incorporating this controller in my power box and with the larger case I will have room to fit one or two more at a future date.

My next job is to work out where everything is going to go. I am going to try to use CoralDraw to lay things out and maybe even produce a template that I can just stick onto the facia to mark out where I need to cut/drill.

Watch this space!

[Stargazer33]

I have just completed the design stage for my mains power supply box.

The first picture shows the positions and sizes of all the holes. The double line around the outside indicates the lip where the facia panels slot into the outer case. The red markings are there to indicate the maximum size of the switches, sockets, knobs etc. so that I could work out the spacing. I didn't want to drill all the holes and then realise that I hadn't left room for the securing nut or switch, socket, holder casing!

The second picture is of the facia lable that I am intending to print off using photographic ink jet paper. I am then going to cut it out completely - including holes - and then spray it with conformal coating on both sides to seal it from the damp. This will then be glued onto the front panel.

I am intending (once I learn how to do it in Corel DRAW) to put graduated markings around the dew heater tape pot knobs (middle row on right hand side) to indicate increasing temperature as the pot is rotated clockwise.

[JAS]

Looks like it will be a nice tidy job.

It may be a bit awkward to use the on/off switches with anything plugged in tho, as the cables will be going over the top of them.

I have also found it useful to put a led after the fuse on each output, this gives instant indication as to what is on or off, or if a fuse has gone.

Hope it workes out well for you.

Jason

Sent from my LT15i using Tapatalk 2

[Stargazer33]

Here are some pictures of my build so far. I am waiting on the missing parts from Maplins - they only stocked 2 of each item in my local branch!!

The keen eyed amongst you will notice that despite all my planning and careful drawings I managed to miss the fact that a couple of the holes had not been aligned properly!

Anyway, here is the build so far:

The 12v supply for the mount is working okay - I am actually getting about 12.35v at the socket. My anti-dew tape controller however has decided to turn into an 'On/Off' switch at the moment and I don't know why! I am sure it was working before I took it out of the original box and put it into this one, but now nothing happens when I turn the pot until I get to the 11 O'clock position and then the next couple of millimeters of travel the output goes up to 12.5v and then as I continue to rotate the pot it almost immediately drops to 12.34v and then stays at that level for the rest of the rotation round to the 5 O'clock position.

[Stargazer33]

Hi Jason,

The intention was to mount the box under my ep tray on the tripod. That way it would be easy to access and the wires should be going up from the sockets and therefore not dangle over the switches. The switches would also only be operated once in a session so if there is dangalage it shouldn't be a problem!

It was my intention to add LEDs for the various circuits later but then I changed my mind. I like your idea of using them as a blown fuse indicator though! Could save a lot of frustration!

Looks like another order to Maplins for some 12v LEDs and a bit of rewiring!

[Stargazer33]

Today I rewired the fuse for the dew controller, putting it before the controller PCB. I am going to add LEDs to all my circuits so that I can tell if a fuse has blown, as per Jasons suggestion a couple of posts above.

I also popped into my local Halfords and got another four of the 6A micro switches and wired them into the case ready for my fuse holders, dc power sockets and dimmer controllers - see below:

I have secured the power converter with a couple of large tyraps that I melted holes in the ends with the soldering iron and then screwed to the case base. I have also temporarily secured the main power LED to the case with leccy tape until I can figure out how to secure it more permanently.

I think my Chinese LED dimmer (dew band controller) has died - probably the MosFET or IC has gone U/S. I had ordered two more to fill the two remaining positions but I am now hearing that these units are very unreliable and keep failing!

I have found a circuit on the internet that uses a 555 chip and I may see about making one to see how it compares to the new Chinese LED dimmers I have ordered. If nothing else it will be something for me to do on the wet January & February weekends!!

[JAS]

Looks like it is coming together Bryan, lets just hope we get some clear nights to use it!!

I drilled holes in my case the same size as the LEDs and pushed them in from behind and put a blob of glue on the back, may work for you? you can also get clips to hold them in if your hole is to big, here: http://www.bitsbox.co.uk/hardware.html I have found this company very good and reliable with low postage cost, and unlike Maplins they have stock

I made a 4 chanel heater controler using 2 556 chips about a year ago, I followed the instructions from here: http://www.simcoeskies.com/dew/no_can_dew.html Its had lots of use and has preformed very well, you wont be disapointed if you do go that way. I have also heard of the chinese units failing from several people.

Jason.

[Stargazer33]

Hi Jason,

My 'Main Power' LED is just pushed through a 3mm hole drilled into the case. I was thinking of just glueing it in place but then I thought 'what if I need to remove it?' I probably will glue it in but using a rubber based glue so that it can be easily removed.

I've added that store to my bookmarks. The prices seem cheaper than Maplin too.

I will see how the new dimmers work when I get them; and how long they last! I did a test on my existing dimmer yesterday with a 12v car bulb and it does adjust the brightness but only over a little over 1/4 of its travel. I have adjusted the start position (by fitting resistors to one end of the track) so that it starts to conduct at the 9 O'clock position and rises to max output - 0.3A - at about the 1 O'clock position.

That dew controller looks simple enough to build. Would be easier with the circuit board, but I could probably manage with veroboard.

[JAS]

I used hot glue for exactly the reason you said

Veroboard was also the way I went, it was my first ever electronics project.

Could you not replace the pot? Maybe they have just used cheap ones.

Jason.

[Stargazer33]

Hi Jason,

Good idea about the hot glue! We've got some at work and I am currently doing the final assembly - minus the two new dimmers which are going to take about 4 weeks to get here from Honkers!

As the dimmer is working, all-be-it with only 90 degrees of adjustment I think I will leave the pot as it is at the moment. I may replace later, but, if it works...

If we ever get a clear night again down here in the south then hopefully I can give my new project a try!

[Stargazer33]

Here is the latest pic for my project.

The facial label is just printed onto ink jet photo paper and then stuck to the face plate with double sided sticky tape and finally a spray of board lacquer as a fixer to stop the ink running.

The rest of the components came today, so tomorrow when I go into work I shall start to wire everything else in. I am still waiting on the LEDs for the fuse indicators and the last two dimmer controllers (about 4 weeks!).

I didn't cut out the holes in the label for the fuse indicator LEDs as I wanted to keep the lights to a minimum. I thought that they could just glow through the paper. If this doesn't work then I can always cut the paper later.

Anyway; here is the pic!

[JAS]

The fascia has come out well Bryan, is bard laquer thae same as used on cars?

What software did you use to draw it out? I have a old project that could do with a printed fascia, this could be the answer.

Jason.

[Stargazer33]

Hi Jason,

Thanks! The board lacquer is another name for conformal coating - it is used to insulate PCBs once they have been populated. I guess any kind of lacquer would do though. I know of artists using hairspray as a fixer for pencil or pastel drawings. So you could use that I guess, although I am not sure if the modern hairsprays have the same components as the old ones used to.

I used CorelDRAW 7 for my fascia label. I set the measurement to mm and that way I could take all the dimensions straight from my box and transpose them onto the label. In the end I did away with the hole markings for the various components as my drilled holes had wandered slightly and the corresponding label was pinched in a couple of places. I removed all the hole markings and just left the legends. I then stuck the label to the box face plate and cut the holes in the label by running round the holes in the face plate with a new scalpel blade. I cut the label from the front, pushing down into the label so as to give a cleaner edge.

I guess you might be able to use GIMP if you haven't got a drawing package. It is supposed to be similar to Photoshop - but free!

[Stargazer33]

I have just finished wiring everything up except for the last two dew heater control boards (Chinese LED dimmers). They will probably be another 2-3 weeks yet.

The third channel on the fixed 12v supply has a dodgy switch - I left the soldering iron on the contact too long and the plastic started to soften!! Still, not a big problem to fix when I get a new switch.

My label has also started to wrinkle - obviously dew to the damp air in the conservatory over night. So that will probably degrade even more on a damp nights observing and will probably have to be replaced at a later date.

The wiring isn't as neat as I would like, or envisioned, but it works and for my first electronics project I am quite pleased.

All I need now is a clear night or even an hour or so of clear sky to test it all out. I would even settle for patchy clouds if I could get a minute or two of observing between clouds! I'm that desperate!!

Oh well, I guess I've always got 'Stargazing Live'.

[Stargazer33]

I finally managed to get outside last night and give the new power box a try. Until I can get an outside power socket fitted the mains cable has to go out through the cat flap - much to the cats' interest and I think annoyance as she can't use it!

Anyway, as the clouds looked like they were rolling in, I did a rough north alignment on the mount with my compass and then a quick two star alignment as I was only intending on doing a bit of observation of Jupiter before the clouds forced me inside. I had to wait for the shopping to be delivered so was inside for about 45 mins and when I went outside the sky had cleared completely!

I had the mount running and tracking Jupiter and the dew heater on high and everything operated fine. Even with only a two star alignment with no calibration stars the mount was keeping Jupiter fairly central for some minutes. To me this was a good indicator that the mount is getting sufficient power to keep it happy, even with the dew heater turned up to max.

All in all I was very pleased with the results - I did succumb and fit my DSLR to take some pictures of Jupiter but they didn't turn out too well even after stacking them in Registax. But the session was all about trying out the new power box anyway, which worked a treat.

[Stargazer33]

Just to close this post, I finally received the last two LED dimmers from HK earlier in the week and fitted them today.

The knobs for the last two dew heater controllers (LED dimmers) are better and sit deeper on the pot shaft so that the shoulder of the knob is virtually touching the mounting. Whereas the original dimmers knob is some way clear of the face plate and you can therefore see the shaft and the securing nut; but that is only asthetics and doesn't affect the way it works at all. I also have the full 9 O'clock to 3 O'clock range on the new pots so I will be able to control the temperature of the heater tape better.

The final job was to put some rubber feet on the bottom of the case to stop it from moving about too much on the patio table and to lift it clear of said surface to stop it from getting too cold (I also place it on a bit of old camping mat for this purpose).

I have decided not to have the heater tape LEDs vary in brightness with the setting as I am only using them to indicate if a fuse has blown.

All in all I am quite pleased with the finished project - observatory here I come!

[Geordieboy46]

Hi all, I know this is an old thread but I'm busy building a distribution hub and have included an arduino temp, humidity & dew-point indicator using 16x2 LCD. In regards to the fuses, can you advise where to put them - e.g. I have 3 x dew heater controllers & also 3 x 12v outputs. I also have a mount power output. Do I put the fuses between the 12v supply & the switch, after the switch or between (for the dew controllers) between the dew controller & dew tape? You advice greatly appreciated - thanks.