Large Scale Central

Low voltage electrical ideas

General Discussion
#41

Bill Z said:

Devon

I ordered those LED panels for my 2 stall engine house.

It is still under construction, but I will take some pics

and post them

Bill

I am very interested in those and it could play an important factor in what I install. I have a couple of competing theories going on here so will need to figure out what to do. Those LED panels are cheap ( I like that) and I am fond of LEDs. I can see them on the floor and then pointing up to a reflective surface (foil) and have some decent dispersion

#42

David Maynard said:

The solder joints were covered with liquid electrical tape to seal and a small plug was placed in line so the buildings were easily removable.

Sealing all your wire connections with silicon so water won’t get to them? Really?? do you seal your rail with silicon as well so water won’t short it out??

You lost me there. You seal your connections, we sealed ours. Its just the choice of sealant is different.

Where I make the connections on the Romex they are close together, I sealed the bare wires so they could not short out if the wire was bumped or moved somehow.

#43

I’ve been using a Malibu ML600TW for my outdoor lighting since 2004 and am very pleased with it. It also has a timer so it turns on and off when you want . I have the transformer in my basement and the wire (12 gauge ) wire runs buried underground all around my yard . When I first teed off the main feeder wire I used a little plastic box thing with spades in it to pierce the wire and make the connection . They worked okay for a few years but eventually some parts of the lighting would work intermittently or not at all. I went back and soldered all the 12 gauge wires together eventually and haven’t had any problems since. I don’t know if the output of the transformer is AC or DC but it is 12 volts. I been using a combination of incandescent and LED’s with a resister with no issues. I’m guessing the run is around 150 feet .

#44

Interesting discussion. So, is it safe to assume (I hate assuming anything) that LED’s can safely be powered with AC current? After all, Christmas light strings are AC, Mike’s Malibu unit is most likely AC, I’ve even got some GFCI receptacles with a small LED in them that let you know it’s working.

-Kevin.

#45

Joseph: There are a lot of good ideas being posted here and all of them have their merits, but no one has answered your question, For the water tight connections you asked about. You would need a small water proof electrical box that you can get at your local hardware and big box DIY store in the electrical dept… They are grey in color. Get one that you can use as a junction box where a number of wires from what ever you want to power will feed into as well as your power source. If you are down ground level you can bury this in the ground and then put a building on top of it to hide it. If you are doing elevated, then just screw the box to a suitable location under the bench work. Were the wires inter the box you need what is called a Plastic Submersible Cord Grips. It is a plastic connector that you would put through a hole in the box and then put the nut on the inside of the box. There is a rubber bushing with O-ring that creates a tight water proof seal after you slide the wire through it and tighten the bushing down. You can get them through McMaster Carr and run about $3.00 each.

With a system like this , you could have a central box n the middle of your town and have all your building feed off this box with all the connections inside the central box and the building all out of the weather. You could also have your power source out of the weather in the garage or shed and run it to the central box as well. If you don’t have a large grouping of buildings, then has a number of smaller boxes daisy changed together and then just tap off the box closest to what ever you want to power. Still using the Plastic Submersible Cord Grips. They come in all sorts of sizes, depending in the wire size you are using.

Hopefully this will answer your initial question.

Dan Stuettgen

#46

dieseldude . said:

Interesting discussion. So, is it safe to assume (I hate assuming anything) that LED’s can safely be powered with AC current? After all, Christmas light strings are AC, Mike’s Malibu unit is most likely AC, I’ve even got some GFCI receptacles with a small LED in them that let you know it’s working.

-Kevin.

Yes, LEDs will run off AC, but it can shorten their lifespan. Using an actual power diode to isolate them from the reverse bias voltage may help them last longer.

#47

No, sorry, it is NOT safe to assume that LEDs can be safely powered from AC.

It really depends on the reverse voltage ratings of the LEDs… on AC you should put a regular diode in series with the LED.

Read any manufacturer’s spec sheet for the reverse voltage ratings.

Greg

(I can also explain why LED Christmas lights can work from AC if needed)

#48

12VDC sign service LEDs make a very nice string of firecracker sound when powered directly with 110VAC (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)

#49

Well here is the big question and I believe it has been answered by both Greg and David but I would like a little clarification. Ok so these low voltage garden lighting units produce 12 volt AC current. I understand the difference between AC and DC so it makes sense why a DC anode would not like AC current. It’s directional where AC is not. Ok I get that. So I am assuming that we all know LED have different voltage requirements and will need a resistor to compensate for the 12 volt and get it to the proper voltage. So we will assume we have made our LEDs 12volt DC. Now how do we make AC to DC? Can we do it at each building feasibly so that we can use a combination of incandescent AC friendly builds and LEDs.

#50

Or would it be better to pick one current type and stick with it. If I want LED do I employ a rectifier and convet the landscape lighting to DC from the get go?

#51

Yes, it might be better to rectify the AC to DC… your ac bulbs will still work. Just be careful to hook the LEDs the right way at first.

But bulbs work differently from LEDs.

Bulbs work on voltage, raise too high and they burn out quicker (or really fast)

LEDs work on current, and basically you put a resistor in series with it to control the current to the LED, even though people erroneously call it a voltage dropping resistor, it is correctly called a current limiting resistor.

There are also small devices that give you a constant 20 milliamperes no matter what the input voltage, which would be best for a varying or unregulated power supply, like a malibu transformer.

Greg

#52

Greg we had this conversation on current versus voltage and LED so I do get what your saying about the resistor being current limiting. Now I also understand how to take 12volt AC and make it 12 volt DC. But your suggesting something still a bit different I think.

You say that with the Malibu being an unregulated source and using something to make a constant current regardless of voltage? Could you explain this a bit more. And is this something that still requires me to convert the whole thing to DC?

I am at this point more inclined to use LED lighting and using the plates like shown. I know that using LED arrays has come along in dispersion especially with employed reflectors. So at this point I would say I would be very interested in taking a Malibu light source rectifying it to DC and then doing what your suggesting to get my LEDs on he circuit reliably

#53

The current limiting gidgets are Suntek CL2 units. Basically they are 2 terminal devices and go in series with your LED, and they automatically limit the current no matter what the voltage, up to 90 volts DC.

There’s been a lot of mention of this in various places.

The issue with unregulated transformers is the voltage is not constant, and if loaded other than lightly, basically the voltage near the transformer is a lot higher than the furthest connection.

Now, if you don’t run a lot of current in the LEDs, then you can pick resistors that work pretty much anywhere, but they also generate heat, so there’s more considerations.

You might just figure out how many lights you need, if it’s just a few, then why go to a lot of trouble. If you want to use the least power, then you would want to go LEDs and you would use a number in series when connected to a 16v transformer.

The rectifying of the AC is easy, just a single full wave bridge right at the transformer.

Greg

#54

Here’s the solution that I worked out for myself. Your mileage may vary. I made a small circuit which takes variable DC or AC, rectifies it to unidirectional DC. Then an LED driver limits the current going to any number of LED’s. I then take the output of the circuit and add LED’s in parallel. You can put from one to at least 14 LEDs on this circuit. I oriiginally make the circuit to power lights in passenger trains where I didnn’t knw how many cars would be in the train at any given time.

I’ve put the same circuit into “blocks” of buildings lit by LEDs.

A couple of years ago, I had some circuit boards printed to simplify the wiring of these circuits. Probably not up to Dave Bodnar’s work, but serviceable if someone would like one reply on this list.

#55

If you add filter capacitors to your rectified AC, then the sine wave and the resulting voltage is over 16 volts from 12 volt transformers, another good reason to use the CL2 device and you can wire several leds in series $ of these on filtered Malibu transformers with a diode bridge and a 25WVDC capacitor that is over 1,000UF. I plan on 1,000 for every amp drawn.

#56

Devon, you can rectify the AC into DC either at the transformer or in the buildings themselves. and yes a filter capacitor placed after the rectifier will help smooth out the pulses, adding a choke (coil) in the circuit will also help. But, really, we don’t need perfectly clean DC, we just need to not reverse bias the LED CL2 combination. So a simple bridge rectifier, in the building with the LEDs and CL2s would do the job. When buying these parts in bulk, they aren’t very expensive. Buying then one at a time at Radio Shack (if you can find one) can get rather pricey.

#57

When sizing leds from AC with just a diode remember the LED circuit sees the AC voltage multiplied by 1.414 (this is peak AC voltage) .

This is 16.9 volts and even with a diode drop of .7 volts it is at least 16 volts seen by the led. Big change in resistor selection!!

Again the CL2 does not care!!

#58

Dan, the CL2 is a wonderful device for our applications. For lighting effects inside passenger cars, where the voltage will vary (if running DC track power) it really simplifies things. For building lighting effects, it just makes the whole thing so much easier.

#59

Does anyone make a commercial made unit to take the “Malibu” power and convert it to where it will run LED building lights? After reading all 3 pages of this it is really clear what I DO NOT know. Maybe with some time,and some video or pictures I can get it but for now I can hope that someone will make something for this task. “Malibu” power seems to be an easy way to go , with direct bury wire and I want LED lighting for less electrical use it provides, and it seem like to me anyway the best way to procede.

#60

Pete, I am sure someone does, but it would be less expensive to make your own. All you need is a bridge rectifier and a CL2 in your building and you are all set.