OL-CH-860 Sound Chaser
Chasing lights (lights turning on and off in sequence) add visual punch to any musical number or show. A chase controller is an electronic device that turns a series of relays on and off according to a prerecorded pattern. To visualize how a chase sequence works, imagine that you have four lights plugged into four separate outlets, each with its own light-switch. To get a chasing effect turn on the first switch, now turn off the first switch and turn on the second switch at the same time. Turn off the second and turn on the third, turn the third off and the fourth on and, finally, turn off the fourth as you turn the first back on. Repeat as needed for your chasing effect. Each instance of one outlet going on while the other is going off is referred to as a "step" in the chase sequence. Some chase sequences are very long and complex, but most tend to be between two and four steps long.
You could, in theory, do the chase effects for your show manually, but it would be a tedious affair at best. A chaser unit is a much better solution as it can run the same chase all night long without getting tired - or wandering off for a beer! It can also change patterns (the sequence in which the relays are turned on and off) or turn all the lights on or off together. Most chaser units include the controller (usually a circuit board) and the relays, or switches, in one box. Some chaser units allow you to control the chase pattern with a footswitch, and some can even chase the lights in time with music.
This last feature, chasing the lights to the music, has made chaser units very popular with mobile DJ's and bar-bands looking to spice up their lighting. After all, those four PAR cans lighting the stage or dance floor can start to look a little dull after the second song. The sound-active chase is achieved by means of an internal microphone that detects strong sounds (like the beat of a kick-drum) and tells the chase controller to advance to the next step of the chase sequence.
Chaser units can be used for more than chasing lights for a band or DJ, though. You can easily make a chasing border for a sign or marquee using four strings of Christmas lights and a chaser unit. The key is to space the strings so that a lamp on the string plugged into the first outlet is followed by one on the string plugged into the second, then the third, then the fourth and then back to the first. By staggering your lights this way, they will appear to chase around the border of your sign or marquee. I have used a technique similar to this to make chasing signs for "Guys and Dolls," the "NYC" number in "Annie" and the backdrop in the finale of "A Chorus Line."
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