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toodle_pipsky
04-20-2008, 04:51 AM
Well I'm at the stage now where I'm looking at powering the whole shebang. In chat I have been told that a Toroidal Transformer will be the way I cut out all those awful wall warts. I have looked through the board and wiki, and while there's some discussion about this stuff, there's no real definitive "this is how you go from power in to power out". In fact the only picture I could find of a set up was one posted by klanger on the old forum, so I couldn't tell from 1 picture what was going on.

Here's some questions I have:
1. How do I work out how many transformers I need - will one do or is there a formula to work out how many I need?
2. I've come across enough discussion about the best places to get them, but are there different types? What type do I need and would question 1 answer this for me?
3. What parts do I need other than the electric donut?
4. Is there anything special about putting it together?
5. Does it just plug into the wall or does it wire into the mains somehow?
6. How does it connect to the lights?
7. FINALLY and most importantly, do I need to get an electrician to do anything?

I'm in Australia, so that's the type of power I'm working with. Like I said, there is enough discussion about "get the stuff from Jaycar" or "I got mine from Dick Smith", so I'm not looking for that. There's a good thread about making them safe by putting a fuse in, so that's the type of instructional help I'm looking for (and hopefully someone else is too). If someone has step by step instructions, that would be fab, better yet, post it to the wiki. Although this is all moot if it's "get an electrician" from the outset.

Thanks for your help, as always it's appreciated!
Cheers,
Ingrid

synnie
04-20-2008, 05:25 AM
First up Ingrid, if you know an electrician who could solder the mains plug/socket for you then go ahead unless you think that would be easy for you. What i did with mine was rip the 3 pin socket out of a puter power supply and soldered it to my Toroidal.
I buy most of my Toroidals and DC power supplies of eBay....thats my preference because of the prices.
http://stores.ebay.com.au/Electronics-Component-Store_Transformer_W0QQcolZ4QQdirZ1QQfsubZ3QQftidZ2 QQtZkm

Heres a reply by DennisB on transformers
http://www.doityourselfchristmas.com/forums/showthread.php?t=2755
read your post again and see you have found it...oops...

To connect it to the lights just need to find the +ve and -ve on the output side.Normally the transformer has details on which is which. Connect the +ve to input on SSR's and -ve to other end of light strings.

To work out what size i needed i got all my 24V power packs and added up the VA or wattage of them all.Roughly working out a 300VA toroidal will be enough to run 10 light sets if they are roughly 24VA each set.Running on 80% of total VA of toroidal... I am only assuming you havent modified your light strings .................................................. .... yet.....................


I did all my wiring up even though im not a lecky, this year i will be throwing in the circuit breaker,last year it was relying on the household breakers to do the job.
Hope this is a help ....
G

aussiephil
04-20-2008, 06:41 AM
Ingrid
Yes perfect topic to be written up and your running a few weeks in front of me - I was leaving my toroid setup till later in the year when i have the final count nailed down.

One thing popped out of the post by Synnie, refering to +v and -v can confuse people to think that DC is present. Just wanted to point this out for real novices to working with AC power.

Looking at the Specs in the Jaycar Catalogue we have
0V and +V
0V should be regarded as the neutral wire
+V should be regarded as the Hot wire

Both wires can be dangerous at ALL times unless switched.

When wiring the outputs in parallel the above is critical. Neutral must go to Neutral. Hot to Hot.

More to come.....

Phil

toodle_pipsky
04-20-2008, 07:10 AM
Thanks for that guys.

That's good news Phil. I won't be starting anything either until I have at least my boards done. So like you said, a few months ahead. Thought I would ask now, being as electricity is serious stuff! It will take me a couple of months to digest all this anyway! ;)

Keep this info coming - it’s all good!

synnie
04-20-2008, 07:13 AM
thanks for that bit Phil...i knew what i meant but couldnt put it into the right words like you did....

jgrei1
04-20-2008, 07:25 AM
ingrid, if you run into trouble just give me a bell.. im only a short drive away

toodle_pipsky
04-20-2008, 07:36 AM
Aaahh my sparky friend! You may regret those words! ;) I'll keep that in mind. Thanks J.

jgrei1
04-20-2008, 07:48 AM
no worries.. pm me if you need my ph number.. BTW you will have abit of competition in toowoomba this year too :)

aussiephil
04-20-2008, 09:51 AM
thanks for that bit Phil...i knew what i meant but couldnt put it into the right words like you did....

I knew what you meant :) as well.

i'm lucky to find the right words most nights....

WWNF911
04-20-2008, 09:28 PM
Aaahh my sparky friend! You may regret those words! ;) I'll keep that in mind. Thanks J.

Wow Toodle, Nice avatar!

toodle_pipsky
04-20-2008, 11:23 PM
Wow Toodle, Nice avatar!

Ha! Thanks. That's me being a moron at work on Christmas Eve last year. Found the pic when I was cleaning up and thought it semi-appropriate.

toodle_pipsky
04-23-2008, 05:12 AM
Ummmm so does anyone else have anything to add? Any hints or tips?

DennisB
04-23-2008, 06:31 AM
[QUOTE=toodle_pipsky;27850]

Here's some questions I have:
1. How do I work out how many transformers I need - will one do or is there a formula to work out how many I need?

Simple add the VA value of the plugins together and that will give you the vale of your Tx. Always have a small safety margin though, 10 or 20VA is plenty.

2. I've come across enough discussion about the best places to get them, but are there different types? What type do I need and would question 1 answer this for me?

As you said read the thread you mentioned, I think I replied to it as well. Torridial Tx will be fine and it doesn't have to be encapsulated. (probably wouldn't find one large enough anyway)

3. What parts do I need other than the electric donut?

Fuses and more fuses, fuse the primary (input) at no more then the rated current and fuse the secondary (output) at no more then rated current.

4. Is there anything special about putting it together?

Nope, not really, remember though, ELECTRICITY KILLS. Again find threads I replied to, they will help.

5. Does it just plug into the wall or does it wire into the mains somehow?

See my thread on "What the 240volt guys are using" and ask more questions if needed.

6. How does it connect to the lights?

Terminal strips on the secondary side after the fuse.

7. FINALLY and most importantly, do I need to get an electrician to do anything?

You should have an electrician check the final work before powering it up. I checked mine myself because I am one.

Hope some of this helps Ingrid.

Regards

Dennis

toodle_pipsky
07-23-2008, 09:29 AM
1. How do I work out how many transformers I need - will one do or is there a formula to work out how many I need?

Simple add the VA value of the plugins together and that will give you the vale of your Tx. Always have a small safety margin though, 10 or 20VA is plenty.


Ok, so I'm back on this again! ;) It's easy enough to follow the above instruction - however what about in the case of split light strings that no longer follow what the original wall wart dictates? For example - 99% of my lights will stay the same and I won't need to do a thing to them so that's easy, but I have two star cut-outs that use 2 series in parallel each (essentially 2 channels each). Each of them come from a string of 200 or so lights and the light count in each of them comes in waaay under that original count - how do I work out how many VA it is? A setting on the multimeter? A simple formula? Or is it just easy enough to use a wall wart to power them instead? (PS I haven’t just willy nilly wired these up – they do work with the original transformer)

Also there are so many different types of transformers - 12V, 25V, 18V etc. What should I be looking for?

Ta!

prof
07-23-2008, 09:01 PM
Hi,

If you have cut down a single string of bulbs to make the star then the load is a simple formula of (bulbs used / original string bulb count) * plugpack VA. "Half the bulbs is half the load".

Here in Aus the common lighting plugpacks that I have seen for incandescent bulbs seem to be 24VAC with a few at 36VAC. So if you are replacing the plugpacks with transformers then for 24V, the 12V-0-12V 300VA toroidal (eg Jaycar MT 2130) - with secondary windings connected in series should typically power up about 12 or so sets of lights (based on 200 bulb strings). For 36V use the 18V-0-18V unit.

Craig

kamahilights
07-26-2008, 08:19 PM
Another good source for large 24ac transformers is large industries that are replacing their MCC's (Motor Control Centres) - large switchboards in other words, as they wear out and get replaced. Until 8 years or so ago all control at my workplace was done using 24 volts AC from LARGE (Up to 3kVa) transformers but all new stuff is now 24v DC to better suit the new PLC's we are putting in.

Guess where all the replaced 24v transformers go? Currently there is a 1.5kVa one sitting on our front deck . . .

daviddth
07-31-2008, 04:01 AM
Got any more you want to get rid of kamahilights? :)

toodle_pipsky
08-31-2008, 10:38 AM
I know toroidal transformers will be covered at the Melbourne Mini, I'm just looking for some advice to get 1 transformer going to test my mega tree lights.

The lights are 2 sets of 36V 48VA, and the trouble is the wall warts that came with them have a controller as part of it, so can't use the original transformer. So I have a 18V-0-18V 160VA TT. Label says 240V ORG-ORG (orange), 18V WHT-PIK (white-pink), 18V YEL-RED (yellow-red).

So question time:
I'm assuming power in is going to be the orange, the other colours are going to be output. I need to connect them so I get 36V out - does it matter what colour is connected out of the white/pink/yellow/red?

Is there a particular combination (out of the above) that should connect to the lights and to the SSR? I assume it doesn't matter - like with any normal wall wart?

Probably simple questions - just don't want blow 800 lights and flush $$ down the drain! Thanks as always.

magott
08-31-2008, 10:12 PM
Generally when setting these up if you connect the secondary windings in series you get double the volts (ie 36volts) and half the current. If you connect in Parallel you get double the amps. From the picture it looks like you connect the yellow and pink together. This should give you the 36v you want. Also check the side of the transformer or technical catalogues like the one from Jaycar as they also show how to connect the leads to achieve this. Dont panic if its wrong you will only get 18V which wont harm the lights. Set it up and test with a voltmeter first. Dont forget that these need to be seperately fused (usually 5 Amp).

TimW
09-23-2008, 04:04 AM
I just came across this comment on one of the toroid sellers site that is worth mentioning - not that its likely to happen. But its kind of important that it doesn't!

"Under no circumstances should both ends of the fixing bolt contact a metal chassis or frame as this would create a 'shorted turn' causing irreparable damage"

The fixing bolt is usually a bolt that comes up through the hole in the toroidal transformer and attaches to a mount that holds the transformer down to the case.

The important safety tip is - don't let the 2 ends of the bolt (underneath and above the transformer) come into contact somehow with a metal case or any other metal that loops around the outside of the transformer. It effectively creates a loop of metal (eg case/bolt/case) through the center of the transformer that will cause nasty currents to flow and aforementioned 'irrepairable damage' apparently.

I'm thinking insulating the top of the bolt somehow might be a safe thing. Just don't earth the top of the bolt to the metal case (No, I'm not saying don't earth the metal case - just don't make a loop!).

As always, be very careful.... or get a careful and qualified person to help if you are not sure.

n1ist
09-23-2008, 09:20 AM
For the secondary, I would try connecting pink to yellow, and measuring between white and red with a meter. If you get a low voltage, try connecting pink to red and measuring between white and yellow. One way should give 36V; all you need to do is get the phasing correct.