On Oct 13, 1:32*pm, klem kedidelhopper
wrote:
On Oct 13, 12:19*pm, nesesu wrote:





On Oct 13, 5:37*am, klem kedidelhopper
wrote:

On Oct 12, 10:48*am, nesesu wrote:

On Oct 12, 6:12*am, klem kedidelhopper
wrote:

I have this unit which I installed many years ago in a new fast food
business. The restaurant failed shortly after it was installed and I
got the equipment back. So in essence it is like brand new.and was
operational when it was removed from service.

The unit is a self contained box with loop sense wires and isolated
spdt relay wires. It operates from 120V. The loop was buried in the
driveway and so I was unable to retrieve that part of the system.

Installation was rather simple. Unfortunately I can't find the
installation instructions however I do recall that we had to cut the
asphalt driveway and bury a loop of AWG. 14 cable. The loop would
sense a large mass of metal over it such as a car, (as opposed *to a
non metallic mass), at a drive through and operate a form C relay.. I
would like to set this unit up in my own driveway now however the
problem is I don't remember the configuration of the loop, IE how many
turns there were in the loop or its diameter. Actually I think that we
buried it down 8 inches or so and that it was rectangular shaped but
I'm just not sure.

There is no longer a listing for Detector systems however the strange
thing is the number 917-1 does come up as some kind of driveway sensor
but I can't seem to find any information on it.

I would think that this type of unit must be similar to those that are
used at intersections for traffic light control but I'm not sure how
to find that information.

Does anyone have any experience with this type of sensor who can
advise me as to the sense loop characteristics? *Thanks for any
assistance, Lenny

A few thoughts on these sensors. Generally, the loop is non critical
and the unit automatically compensates for variation. The loop is
somewhat standardized since one does not dig up the road to change the
loop if the detector unit needs replacing. I seem to recall that the
loop is typically about 4' x 8' and about 2 or three turns. One could
easily tape a test coil to the driveway and try it out. Usually, the
coil is buried about 3-4" into the asphalt.
Try looking up the oldest sensor info you can find [Eagle signals?]
and see what info it has on the coil.
Usually, the connections on the quality sensors is by a single 'MS'
type circular connector with 8 connections. You should be able to open
the case and trace the pinout. Connections should be: AC input [line,
neutral, ground], Output [NC, COM, NO] and LOOP.
You could also check with your local roads department's electrical
shop. Good luck!

Neil S.- Hide quoted text -

- Show quoted text -

Hi Neil
I made a coil in the configuration you described out of 14AWG. wire.
The coil is 4 turns of wire with a 4 X 8 rectangular shape. The
perimeter is 96" approximately. I just realized that this is a larger
perimeter than you suggested so I wonder if that might cause a
stability problem such as I'm having? The funny thing is with this
coil the control unit will sometimes detect the vehicle every time on
the approach, (within 2 feet of the car even before the car passes
over it. At other times there is no detection at all. I tried the
different modes, pulse, 2 second delay, presence, *and messed with the
sensitivity. So I'm wondering if I need more or less turns or maybe a
different loop size.
I could be wrong because this was a long time ago but the driveway may
have been about 8 feet wide. The cuts we made for the coil may have
been much narrower than this coil. Those cuts could have been 8 feet
by say 4 or 5 inches or so. Do you think that could have been
possible.? Would configuration and size cause a reliability problem
such as I'm having? This is so frustrating. I know that the system
worked well at the time. I just can't remember exactly what we did.
Thanks for any further input. Lenny- Hide quoted text -

- Show quoted text -

Lenny, I am a bit puzzled by your coil description. You say it is 4 x
8 and 4 turns, but has a perimiter of 96". Since 96" is only 8', I
would think that the coil you made would have a perimiter of 288". Try
and reduce the coil to 3 turns, but don't cut the wire off. The leads
from the unit to the coil should be twisted together or you can get
some funny results due to stray pick-up. Normally, the unit should not
pick up the car until it is on top of the coil--it sounds like you
have too much sensitivity--which is why I suggest reducing the coil
turns. I have also never seen more than 2 or 3 turn coils, but that
does not mean much.
I cannot say I have seen any really narrow coils like you describe,
but some on driveways are like 4' x 3' and the newer ones on the
highway are about a 4' circle [neat machine that cuts the circular
slot in the road surface]. Size and configuration are THE important
thing in these coils, so it needs to be right for that unit. It is
really not much different that getting a radio back loop antenna to
track the tuning dial--a fair bit of cut-and- try.

Neil- Hide quoted text -

- Show quoted text -

Hi Neil
You were correct. The coil is comprised of two 96" sections and two
48" sections for an approximate *total of 288".
You mentioned that the coil I constructed might make the system too
sensitive. If that were the case then why does it trip the unit
sometimes and just as the car approaches and then not at all at other
times? I would think that too sensitive would cause false tripping to
occur at random times as well. but I'm not really seeing that. but for
certain, I'm no expert with this type of equipment. I'm going to take
one turn off the existing coil however I didn't quite understand what
you meant by "not cutting the wires". If I reduce the number of turns
to 3 and not cut the wire I will have one lead longer than the other.
That in itself I would think would cause an imbalance. Should I then
just add the difference onto the shorter lead, twist them together and
then connect to the short pair of twisted wires (loop), coming out of
the unit?.
Also one other thing concerns me. right now we're just testing this
system with a coil laying on the ground and the controller connected
to it right there. If I do get this thing working reliably, ultimately
the coil will be buried about 150 -200 feet from the house. I planned
to run two conductor sheilded cable, burried and grounded on the unit
end out to the coil. Alot of work. What is the chance that the
addition of this cable may alter the impedance of the system to the
point of putting me right back to where I am now? Lenny- Hide quoted text -

- Show quoted text -

Neil
Just an update. I removed one turn from the coil and added the
difference onto the shorter wire. I twisted the wires together. so the
lead in so to speak is now about 290 or so inches of twisted pair 14
AWG. There are four dip switches in the control box. One is marked
"presence" and "pulse". Presence requires that the vehicle occupies
the space for two seconds in order to trip the relay. For fast food
restaurants and such I seem to remember that is the correct setting
but for simple detection like I need I think we want the "pulse"
setting. There is another switch marked "two second delay" and "off".
I think that switch is related to presence and pulse and so I set that
one "off". There are two other switches which I think are related to
sensitivity however their markings are very ambiguous. There seems to
be a high, med, and low combination of these printed on the circuit
board but it makes no sense at all. I'm not sure what those settings
are I did note though that when both these switches are in the off
position. the vehicle is detected when the front end is about two feet
from the coil. Sliding one of these switches to the right makes it so
that the vehicle has to have one foot of its front end over the coil..
So it would appear that this combination makes the system less
sensitive.
Another interesting observation was that moving the coil around a bit
with my foot would sometimes set off the relay. Maybe thats not a
valid test though. Lenny.