Possibly OT but anyone know anything about and ideally where to get an
old style petrol attendant "sevice" bell ?
(the bit of black rubber hose? that you used to see stretched out
across the garage forecourts - when your wheels went over it it rang
a bell in the office to alert the pump attendant to your presence....)

ta
Jim

jim coughed up some electrons that declared:

Possibly OT but anyone know anything about and ideally where to get an
old style petrol attendant "sevice" bell ?
(the bit of black rubber hose? that you used to see stretched out
across the garage forecourts - when your wheels went over it it rang
a bell in the office to alert the pump attendant to your presence....)

ta
Jim

You could probably make one - all you'd need is some rubber pipe and a
pressure switch (something from RS or Farnell, or even a washing machine
water level switch (air pipe into water type) is probably in the right sort
of range.

Cheers

Tim

On Sun, 24 May 2009 20:51:37 +0100, Tim S wrote:

You could probably make one - all you'd need is some rubber pipe and a
pressure switch (something from RS or Farnell, or even a washing machine
water level switch (air pipe into water type) is probably in the right sort
of range.

If you're going to operate an electric bell from the pressure sensor line
then another source is air pressure switches from many boilers, often
available as scrap. However it would be neat to have the air pressure ring
the bell directly, which would require a bit more ingenuity.


--
John Stumbles

A: Because it messes up the order in which people read text.
Q: Why is top-posting a bad thing?

"Tim S" wrote in message
...
jim coughed up some electrons that declared:

Possibly OT but anyone know anything about and ideally where to get an
old style petrol attendant "sevice" bell ?
(the bit of black rubber hose? that you used to see stretched out
across the garage forecourts - when your wheels went over it it rang
a bell in the office to alert the pump attendant to your presence....)

ta
Jim

You could probably make one - all you'd need is some rubber pipe and a
pressure switch (something from RS or Farnell, or even a washing machine
water level switch (air pipe into water type) is probably in the right
sort
of range.

yup, it is an amazingly simple devise, i used to work at a self service
garage that had this set up,

The hose was special soft easily colapsable hose, and used to split after
about 6 months use, it was more of a sponge rubber,

the ends were knotted, i guess at one time proper plugs or caps would have
been used, the other ends went into the old car show room into the electric
cupboard,
where the hose was pushed onto a pressure switch, about the size of a tea
cup, was a diaphram inside, spring loaded with an adjustment screw in the
middle, the slight pressure wave of a vehicle driving over the hose
dperessed the diaphram, and the switch rang the bell,

unfortunately at that place they used a 'rrrriiiiinnnggggg' type door bell,
which was fine if cars ran over it, it's go 'ding ding' but when the trucks
came to fill up one of hteir trailer tyres would be on the hose, and the
damn bell would ring all the time.

Also had to adjust the sensativety of the switch every few days if the
weather changed a lot, but half of that was down to them trying to use
normal pvc hose which sent a much lower pressure wave to the switch as it
didnt crush much.

gazz coughed up some electrons that declared:


where the hose was pushed onto a pressure switch, about the size of a tea
cup, was a diaphram inside, spring loaded with an adjustment screw in the

That sounds about the same form factor as a washing machine level sensor.


unfortunately at that place they used a 'rrrriiiiinnnggggg' type door
bell, which was fine if cars ran over it, it's go 'ding ding' but when the
trucks came to fill up one of hteir trailer tyres would be on the hose,
and the damn bell would ring all the time.

Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

"Tim S" wrote in message
...
gazz coughed up some electrons that declared:

unfortunately at that place they used a 'rrrriiiiinnnggggg' type door
bell, which was fine if cars ran over it, it's go 'ding ding' but when
the
trucks came to fill up one of hteir trailer tyres would be on the hose,
and the damn bell would ring all the time.

Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

i'm not that old, this was in about 1995... prolly one of the last remaining
full attendant service petrol stations around, and was only self service
because the boss was too tight to get new pumps that could be controlled
from inside, hence it had to be attendant service by law as no way to shut
the pump off if someone did something silly with it.

In article ,
Tim S writes:
Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

They were called road pad detectors.

Originally they used a pair of sprung steel plates held apart along
the edge, which deform and make contact with vehicle weight (but
supposedly, not by jumping on it). A twin version allowed detecting
direction of traffic, but was often used because when one unit broke,
the controller could be connected to the other one until they could
be replaced, which was required on a routine basis.

There were a number of attempts by the likes of GEC and probably
Plessey too to come up with longer lasting inserts for the iron
holders, and I did see pressure tubes.

Inductive loops have taken over now of course, and they work with
cyclists too.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 25 May, 09:38, (Andrew Gabriel) wrote:
In article ,
Tim S writes:

Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

They were called road pad detectors.

Originally they used a pair of sprung steel plates held apart along
the edge, which deform and make contact with vehicle weight (but
supposedly, not by jumping on it). A twin version allowed detecting
direction of traffic, but was often used because when one unit broke,
the controller could be connected to the other one until they could
be replaced, which was required on a routine basis.

There were a number of attempts by the likes of GEC and probably
Plessey too to come up with longer lasting inserts for the iron
holders, and I did see pressure tubes.

Inductive loops have taken over now of course, and they work with
cyclists too.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

inductive loops eh... could you describe how they work please? - are
they DIY-able?

ta
Jim

On 25 May, 09:38, (Andrew Gabriel) wrote:
In article ,
Tim S writes:

Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

They were called road pad detectors.

Originally they used a pair of sprung steel plates held apart along
the edge, which deform and make contact with vehicle weight (but
supposedly, not by jumping on it). A twin version allowed detecting
direction of traffic, but was often used because when one unit broke,
the controller could be connected to the other one until they could
be replaced, which was required on a routine basis.

There were a number of attempts by the likes of GEC and probably
Plessey too to come up with longer lasting inserts for the iron
holders, and I did see pressure tubes.

Inductive loops have taken over now of course, and they work with
cyclists too.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

inductive loops eh... could you describe how they work please? - are
they DIY-able?

ta
Jim

In article ,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Andrew Gabriel wrote:
Inductive loops have taken over now of course, and they work with
cyclists too.

Since when did the state of a traffic light matter to a cyclist? ;-)

--
*Suicidal twin kills sister by mistake.

Dave Plowman London SW
To e-mail, change noise into sound.

jim coughed up some electrons that declared:


inductive loops eh... could you describe how they work please? - are
they DIY-able?

ta
Jim

Have a hunt around on google for metal detector circuits and try Elektor
magazine.

Alas you'll have to buy a subscription to actually read these, but:

http://www.elektor.com/magazines/200...or.57240.lynkx
http://www.elektor.com/magazines/200...or.55389.lynkx

There's a free one he

http://www.easytreasure.co.uk/bfo.htm

If you can whack a few transistors and/or DIL chips together, you can make
one, for very little money.

In article ,
"Dave Plowman (News)" writes:
In article ,
Andrew Gabriel wrote:
Inductive loops have taken over now of course, and they work with
cyclists too.

Since when did the state of a traffic light matter to a cyclist? ;-)

Well, _I_ still obey them as a cyclist, although I admit that
I'm in a vanishing minority, along with wearing reflective
materials and having working lights.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Dave Plowman (News) wrote:
In article ,
Andrew Gabriel wrote:
Inductive loops have taken over now of course, and they work with
cyclists too.

Since when did the state of a traffic light matter to a cyclist? ;-)

Doesn't matter to them at all, they don't contribute towards them,
scrounging gits.

BTW - did you know that MP's can claim 20p per mile for travelling by
bicycle?

You couldn't make it up could you?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Andrew Gabriel wrote:
In article ,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).

IIRC below a certain level of emission you dont need any license or
approval. Cant remember what power that is though, but its a small
fraction of a watt, and doesnt trasmit far.


NT

The Medway Handyman wrote:

BTW - did you know that MP's can claim 20p per mile for travelling by
bicycle?

So can anyone.

http://www.hmrc.gov.uk/manuals/senew/SE31240.htm

How about a MedwayHandyBike?

On Mon, 25 May 2009 10:23:29 GMT The Medway Handyman wrote :
BTW - did you know that MP's can claim 20p per mile for
travelling by bicycle?

You couldn't make it up could you?

Got to keep Dave and Boris happy! But any business can pay an
employee 20p per mile for using a cycle. This will be an allowable
business expense set against tax and tax free to the recipient.

http://www.hmrc.gov.uk/rates/travel.htm

--
Tony Bryer, 'Software to build on' from Greentram
www.superbeam.co.uk www.superbeam.com www.greentram.com

Andy Burns wrote:
The Medway Handyman wrote:

BTW - did you know that MP's can claim 20p per mile for travelling by
bicycle?

So can anyone.

http://www.hmrc.gov.uk/manuals/senew/SE31240.htm

Absolute disgrace! Shouldn't be allowed.


How about a MedwayHandyBike?

I'm 200' above sea level! Never get back up Watling Street!



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On 25 May 2009 09:41:26 GMT
(Andrew Gabriel) wrote:

In article ,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).


Not really, they are inductors. The inductance of a loop changes when
a piece of iron (and some other) materials pass close by. If the
inductor (the coil buried in the road) is in a tuned circuit then some
characteristic of that circuit can be used to detect when the
inductance changes. There are no radio emissions, it's just
electromagnetism.

See, for instance:
http://www3.telus.net/chemelec/Proje...p-Detector.htm

They used to be sensitive enough to detect a bicycle, but with all the
Carbon-Fibre these days I suspect not.

R.
(who used to work for GEC-Elliott Traffic Automation, back before the
flood)

wrote:
Andrew Gabriel wrote:
In article
,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).

IIRC below a certain level of emission you dont need any license or
approval. Cant remember what power that is though, but its a small
fraction of a watt, and doesnt trasmit far.

In the context of the OP's question e.g. a garage bell, perhaps the signal
could be transmitted with a wire?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

In article ,
TheOldFellow writes:
On 25 May 2009 09:41:26 GMT
(Andrew Gabriel) wrote:

In article ,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).


Not really, they are inductors. The inductance of a loop changes when
a piece of iron (and some other) materials pass close by. If the
inductor (the coil buried in the road) is in a tuned circuit then some
characteristic of that circuit can be used to detect when the
inductance changes. There are no radio emissions, it's just
electromagnetism.

Um, that's an aerial.
Providing you can show your device lays within the power ratings of
table 3.12 of
http://www1.bsc.org.uk/radiocomms/if...R2030final.pdf
then it's exempt from licensing.

See, for instance:
http://www3.telus.net/chemelec/Proje...p-Detector.htm

They used to be sensitive enough to detect a bicycle, but with all the
Carbon-Fibre these days I suspect not.

R.
(who used to work for GEC-Elliott Traffic Automation, back before the
flood)

Snap! It was called GEC Traffic Automation when I was subcontracted
to them from GEC Computers. Many years later, I was working back in
the same building, and GEC Computers and GEC Traffic Automation had
a bowling league each Monday evening, until the Traffic guys suddenly
won the Pools, stuck up 2 fingers to their management, and left!

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

TheOldFellow wrote:

Not really, they are inductors. [...] There are no radio emissions,
it's just electromagnetism.

And "just electromagnetism" means that a time-varying current flowing in
any wire loop _will_ create a radio emission, i.e. an E-M far field with
its amplitude falling off as 1/distance. This follows from Maxwell's
equations, as sure as eggs is eggs.

Sure, in an induction application like this it's likely to be the
magnetic near field that is being used, this being much stronger near
the coil, but falls off rapidly as 1/(distance)^3. The source
oscillator and the coil/loop don't know that however, and happily
radiate both components.

The ferrite rod aerial in any LW/MW radio and its predecessor the frame
aerial used on some old valve sets are examples of the same principle in
reverse - small current loop receives E-M radio field.

--
Andy

On 25 May, 12:04, TheOldFellow wrote:
On 25 May 2009 09:41:26 GMT



(Andrew Gabriel) wrote:
In article ,
jim writes:

inductive loops eh... could you describe how they work please? - are

A sort of up-side down metal detector, i.e. the metal detector
is buried in the ground and detects metal passing overhead.
Google is you want to know more.

they DIY-able?

Yes, but possibly not legally. I don't know what the radio licence
requirements are, but whatever, you're unlikely to have the tools
necessary to prove they meet the radio licence requirements (as
they are radio transmitters).

Not really, they are inductors. The inductance of a loop changes when
a piece of iron (and some other) materials pass close by. If the
inductor (the coil buried in the road) is in a tuned circuit then some
characteristic of that circuit can be used to detect when the
inductance changes. There are no radio emissions, it's just
electromagnetism.

See, for instance:http://www3.telus.net/chemelec/Proje...p-Detector.htm

They used to be sensitive enough to detect a bicycle, but with all the
Carbon-Fibre these days I suspect not.

R.
(who used to work for GEC-Elliott Traffic Automation, back before the
flood)

excellent! thanks for that link - that is EXACTLY what I am after -
now hope I can build it!

Cheers to all

Jim

On 25 May 2009 12:22:16 GMT
(Andrew Gabriel) wrote:

R.
(who used to work for GEC-Elliott Traffic Automation, back before the
flood)

Snap! It was called GEC Traffic Automation when I was subcontracted
to them from GEC Computers. Many years later, I was working back in
the same building, and GEC Computers and GEC Traffic Automation had
a bowling league each Monday evening, until the Traffic guys suddenly
won the Pools, stuck up 2 fingers to their management, and left!



Boring Wood? I was there for just over 18 months in 1974-5. Thank God,
I was head-hunted away.

Good for the Pool's winners!

R.

In article ,
TheOldFellow writes:
On 25 May 2009 12:22:16 GMT
(Andrew Gabriel) wrote:

R.
(who used to work for GEC-Elliott Traffic Automation, back before the
flood)

Snap! It was called GEC Traffic Automation when I was subcontracted
to them from GEC Computers. Many years later, I was working back in
the same building, and GEC Computers and GEC Traffic Automation had
a bowling league each Monday evening, until the Traffic guys suddenly
won the Pools, stuck up 2 fingers to their management, and left!

Boring Wood? I was there for just over 18 months in 1974-5. Thank God,
I was head-hunted away.

Yes.

It was probably about 1985 when I was subcontracted there,
helping them out with communications between each traffic
light controller and the central sequencing computers.

Good for the Pool's winners!

I think this was about 1993.
They had just gone through a round of redundancies, where
strangely, lots of engineers got fired, and no managers.
They claimed that left them with more managers than people
to manage. Then the engineers' Pools came up, and they took
great delight in just quitting, already being very cheesed
off with their management. After a month or so, all their
kit just got dumped by the goods lift as rubbish, and I
think that must have been the end of that group. In the
piles of rubbish were loads of toughened glass faceplates
for pedestrian crossings with the little red and green
men on them, two of which have made very handy little
cheese boards and amusing conversation pieces ever since
(particularly the one in arabic).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Andrew Gabriel wrote:
They had just gone through a round of redundancies, where
strangely, lots of engineers got fired, and no managers.

Of course. Who decides where redundancies are needed?

Bit like MPs saying they only followed the rules for claiming allowances.
And they ok'd those rules...

--
*I am a nobody, and nobody is perfect; therefore I am perfect*

Dave Plowman London SW
To e-mail, change noise into sound.