By St. Nicholas Vinen
Our spectacular Digital Lighting Controller, which we presented last year (October-December 2010), could drive an impressive array of incandescent globes.
But while it proved to be very popular, no sooner had we gone to press than many readers started reminding us that most Christmas Lights are now made of 12V LED strings. D’oh!
So now we’ve made up a new Slave Controller. It suits the original master unit but can now drive up to eight strings of LEDs, each string with completely individual control.
And you can have up to four slaves so that you can drive up to 32 channels.
Furthermore, if you run the whole shebang from 24V DC instead of 12V DC, you can have twice the number of LED strings, by running LED strings in series.
Wow! Think of the possibilities. You can control thousands of LEDs!
Another – these days fairly significant – advantage of going LED is that controlling lots of incandescent lamps means that you are going to get a big electricity bill for the festive season. LEDs are a much cheaper proposition.
Digital LED control
This rear-view inside shot shows the complete Digital Lighting Controller LED Slave - it uses the same master unit as published this time last year. By comparison with last year's slave, the biggest difference is the size of the box - it's much smaller - and the row of semiconductors down the middle - the Triacs are now replaced by Mosfets.
Before we get down to the details of the Slave LED Controller, we need to review the main features of the Digital Lighting Controller presented last year.
The whole system is controlled by the master unit which is housed in a small plastic box. This is controlled via a hand-held remote and takes an SD card (or MMC or SDHC card).
This contains WAV music file(s) and sequencer file(s) (which you set up) and it sends serial commands via a Cat5/6 cable to the slave lighting controllers. These can drive incandescent lights or as presented in this article, lots of LED strings.
You can have up to four slave units and so you could have, for example, three slave units each driving LEDs and one slave driving incandescent lamps. Or any other combination involving up to four slaves.
For the rest of this article we will concentrate on the slave LED controller. If you want all the information involving the incandescent controller and the master unit itself, you will need to refer back to the original articles (ie, October, November & December 2010).
Fig.1: the block diagram shows how four slaves can be connected to the master unit, for up to 32 individually controlled lighting channels. This is one example of a slave lineup; you can mix and match as needed.
If you don’t have these issues, you can purchase them from SILICON CHIP or you can access them on our website (for a small fee).
Going to the Master and slave LED controllers, Fig.1 shows the overall set-up with one master and up to four slaves.
The slave units are daisy-chained via Cat5 ethernet cable, as each has RJ45 input and loop out jack sockets. In addition, to enable a large lighting display to be set up, the connecting cables can be up to 30 metres long.
This means you can have the master unit safely inside your home and the slave units can be a long way distant, provided you can feed 12 or 24V DC to them to power the LED strings.
While the incandescent light slave controller is housed in a relatively large plastic instrument case (as it has to accommodate eight Triac circuits and eight IEC power sockets), the LED slave controller comes in a compact plastic case about the same size as the master unit.