Daktronics C44 - Manual (Page 56)

A-4 Infrared Photocells
At sensing distances up to three feet finding the target with the sensor beam may
be difficult. Take a second target and walk backwards away from the sensor,
always keeping the target aligned to the beam (up/down/right/left target
movement; observe LED indicator). After the target's mounting surface has
been reached, the correct target position or necessary sensor orientation changes
will be obvious.
3. Turn the sensor's sensitivity control to the fully clockwise position. (This is a 15-turn
control, clutched at both ends of travel).
4. Place the object to be detected at the sensing position. If the alignment indicator LED
goes off, check operation by alternately removing and replacing the object. The LED
should follow the action by coming on when the object is not present and going off
when the object is present. If this occurs, alignment is complete. Note: A steady on
condition of the LED with the object absent is the best situation, but this may not
always be possible to achieve.
5. If the alignment indicator stays on when the object is present at the sensing position,
the photocell is reacting to light reflected directly from the object (proxing is taking
place). Reduce the sensitivity (counterclockwise rotation of the adjustment) until the
alignment indicator LED goes off, plus two more full turns. Remove the object from
the sensing position and check that the alignment indicator LED goes on steadily or is
pulsing at more than two beats per second, then repeat step #4 (above).
A.4 Installation and Alignment: SM30 Series Barrel
Sensors
The SM30 Barrel Sensors are used at the start line because they eliminate cross talk by using
different modulation frequencies for each pair. We use an “A” frequency pair for the stage
line, and a “C” frequency pair for the pre-stage and guard beam. The photocells are very
durable and have an effective range of up to 700 feet. When setting up photocells, make sure
to follow IHRA and NHRA rules for distances and heights.
For alignment:
1. Use the SM30 mounting brackets and secure them to the track. Mount the emitters to
the outside brackets and loosely tighten them down. Mount the receivers on the inside
of the track and loosely tighten them down.
2. If you know the exact location where the emitters are to be, securely tighten them to the
mounting brackets. Apply power to the emitters and make sure the red indicator LED
is on to show it is sending a beam and is powered up.
3. After you have powered up every emitter, apply power and signal to each receiver, then
line up each corresponding receiver by using the indicator LED on top of each receiver.
If the LED is on, the photocell pair is lined up and all it needs is some fine-tuning to
set your rollout distance.
4. Test each photocell pair after they’ve been lined up by putting your hand in front of the
receiver. The LED indicator should go out when it is blocked. Remove your hand and
the LED will come back on. Have somebody take a voltmeter and measure the voltage
on the isolation interface where the respective photocell input is. It should measure
less than 1 VDC when the beam is not broken. When the beam is broken, the voltage
should read around +12 VDC (
"2 VDC). If it does, these test okay, make sure
everything is tightened and the alignment is complete.