User's Manual

AMB i.t. B.V. Installation Manual AMBrc - Rev. 1.1b 7
Loop installation for temporary tracks.
In some situations it may not be possible to have the detection loop installed permanently
in the track. This can be the case with temporary tracks, like indoor race events and
parking lot racing. In that case a detection loop installed on a bridge can be used.
Do not
make this bridge of any type of metal or carbon fiber, as these materials will highly
reduce the sensitivity of the loop, resulting in far less reach of the transponder.
For temporary loop
installations, the loop wires
may be connected to the
connection box wires with
help of a good quality
connector such as a terminal
block. (Please note that bad
connections in a loop or coax
connections are by far the
most frequent cause of
substandard performance).
For temporary loops any wire
similar to the AMB loop wire
can be used. Opposite to the
connection box a resistor of
470-ohm (0.15-1 watt) must
be installed. For best results
please solder all joints and
insulate well. For outdoor
soldering a propane fired
soldering iron works best.
When using a bridge make sure the detection loop has a width of 45 cm / 1.5 ft. The
bridge should cover the track width and no RC model cars should be able to pass outside
the bridge. The connection box must be mounted on top of the bridge in order to avoid
loose detection wires, which can cause interference. At all times, keep all wiring as short
as possible. Construct the bridge with sufficient rigidity so it can withstand crashes from a
RC model car. To make sure the received transponder signal is strong enough
,
the
distance between the bridge and the track may not be more than 45 cm / 1.5 ft. Preferably
keep the height of the loop on the bridge as low as possible.
Compared to the in-track loop, the downside of a bridge is the greater distance between
the passing transponder and the detection loop resulting in a weaker signal for the
decoder.
At sundown and at night, the interference from short wave radio signals intensifies
strongly and may occasionally cause the transponder signals get swamped by the
interference. To prevent this from occurring it is advisable to keep the bridge as short
(less than 3 m / 10 ft) and low as possible (less than 45 cm / 1.5 ft).
Jeff Blackborn’s loop bridge used in the HPI Challenge race,
Castle Hobbies of San Jose, CA