User guide

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DAC
Selection
The pan and tilt channels use a DAC to provide high resolution micro-
stepping. The pin LDAC is driven to ground potential by the AL4800
allowing a number of compatible parts to be used. The AD7305 is the
design reference part. The Maxim MAX506 can also be used.
Colour
& Gobo
The colour and gobo channels use a sensor pin to provide a position
reference to calibrate the wheel. The Colour (Gobo) Index pin should
be pulsed low to indicate the reference position.
The reference position should preferably be generated by an opto
slot sensor. A low resistance pull-up of approximately 1K0 is advised
tin order to reduce the possibility of spurious triggering.
The following table shows the position of each wheel stop in both
stepper counts and degrees.
Position Count (0-200) Angle (0-360)
Index 1 -7.2
Position 1 5 0
Position 1-2 15 18
Position 2 25 36
Position 2-3 35 54
Position 3 45 72
Position 3-4 55 90
Position 4 65 108
Position 4-5 75 126
Position 5 85 144
Position 5-6 95 162
Position 6 105 180
Position 6-7 115 198
Position 7 125 216
Position 7-8 135 234
Position 8 145 252
Position 8-9 155 270
Position 9 165 288
Position 9-10 175 306
Position 10 185 324
Position 10-1 195 342
Dowser
The dowser channel moves a total angle of 22.5º. A resolution of 50
steps is provided within this range.
Power On
Calibration
At power on, the following events occur:
• Colour Wheel rotates until index position is found.
• Gobo Wheel rotates until index position is found.
• Dowser drives into closed position.
• Pan & Tilt drive into end stops.