LVT

Low Voltage Transformers

• These are used for most christmas lights in Australia and New Zealand.

• Light strings are supplied with a plug in transformer, known as a wall wart in the USA. These are usually not used in do it yourself lighting shows and are typically replaced by Toroidal Transformers. Toroids are used in Australia generally due to availability from common sources like Jaycar and Altronics.

• The image below shows some of the common connections that could be made.

This is the concept of how to hook them up.

As for calculating the required currents. For every string write down the total wattage (VA) and the bulb count. ie... 20VA and 200 bulbs. Divide watts/bulbs to get bulb wattage. ie 20/200 = .1w per bulb (this is often written on the box)

This value is used when you add or subtract bulbs on each channel.

Now let's do something to work out the number of bulbs per transformer. Easy way 300VA transformer / .1w per bulb = 3000 bulbs a 10% allowance should be allowed for variance in wattage and inrush currents this gives around 2700 bulbs per 300VA transformer.

Now for a SSR with 1A per channel rating. 24v supply at 1A is 24VA = 240 bulbs for .1w bulbs.

For a 4 channel SSR we can have around 1000 - 0.1w bulbs so we could power around 3 x 4ch SSR's with maximum bulbs per channel.

All the above is assuming the 0.1w bulb rating.