switching off a street light with a laser

has anyone managed to prove this theory?

apparently it is possible to point a laser pointer at the
light dependent resister or photo transister mounted on
the top of a street light to fool it into thinking its day time,
thus saving the local authority money, not burning up so much of the
Earths resorces therefore reducing carbon emissions.
unfortunately a regrettable side effect of this is that we all have
darker skies :-)

Simon

Simon wrote:
has anyone managed to prove this theory?

Let's just say that it's more than just a theory. :-)

You can also put a crappy department-store telescope to good use for
this purpose. Aim it at the sensor, remove eyepiece, hold camera flash
at prime focus, fire, enjoy the demonstration that optical systems work
in reverse as a collimated beam of light ultimately darkens your local
environment....

(The flash-at-prime-focus technique is also great for playing "star
wars" at clouded out group observing sessions, especially if it's
slightly misty...)

Best,
Stephen

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Stephen Tonkin wrote:
Simon wrote:
has anyone managed to prove this theory?

Let's just say that it's more than just a theory. :-)

You can also put a crappy department-store telescope to good use for
this purpose. Aim it at the sensor, remove eyepiece, hold camera flash
at prime focus, fire, enjoy the demonstration that optical systems work
in reverse as a collimated beam of light ultimately darkens your local
environment....


But don't they just switch back on again ?

--
Boo

"Boo" wrote in message
.. .

But don't they just switch back on again ?

--
Boo

Not immediately, because 'they' is actually a light-activated switch, clock
and timer circuit. Street lights turn on and off automatically based on
lighting conditions and time of day. To allow for flicker, passing car
headlights, clouds, etc. etc., once triggered, the light remains on or off
for a sustained time period. When it eventually does come back on, one
assumes that those of dubious intent might give it another blast with the
laser.

In message , TeaTime
writes

"Boo" wrote in message
. ..

But don't they just switch back on again ?

--
Boo

Not immediately, because 'they' is actually a light-activated switch, clock
and timer circuit. Street lights turn on and off automatically based on
lighting conditions and time of day. To allow for flicker, passing car
headlights, clouds, etc. etc., once triggered, the light remains on or off
for a sustained time period. When it eventually does come back on, one
assumes that those of dubious intent might give it another blast with the
laser.

I say! This sort of thing isn't cricket you know!!
--
John

John wrote:
I say! This sort of thing isn't cricket you know!!

I know. It's applied optics. :-)

Best,
Stephen

Remove footfrommouth to reply

--
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://astunit.com +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Simon wrote:
has anyone managed to prove this theory?

apparently it is possible to point a laser pointer at the
light dependent resister or photo transister mounted on
the top of a street light to fool it into thinking its day time,
thus saving the local authority money, not burning up so much of the
Earths resorces therefore reducing carbon emissions.
unfortunately a regrettable side effect of this is that we all have
darker skies :-)

Simon


Does anyone know what type of pointer is best? I've been looking on ebay
and there's loads. Red, Green, Any thoughts?

Cheers John DH

"JohnDH" wrote in message news:45832c5f.0@entanet...

Does anyone know what type of pointer is best? I've been looking on ebay
and there's loads. Red, Green, Any thoughts?

Cheers John DH

The photocell used to control street lights is chosen to peak on normal
sunlight, so green would be a much better choice than red.

whilst im no expert I would be supprised if the lampost`s
makers/designers chose photo sensitive device that
worked on specific wavelengths, but yes the lampost
needs to switch with daylight.

There must be a delay circuit
in them to stop the lights flickering on and off when the light level
is hovering about the switching threshold

"TeaTime" wrote in message
...

"JohnDH" wrote in message news:45832c5f.0@entanet...

Does anyone know what type of pointer is best? I've been looking on ebay
and there's loads. Red, Green, Any thoughts?

Cheers John DH

The photocell used to control street lights is chosen to peak on normal
sunlight, so green would be a much better choice than red.

Simon wrote:
whilst im no expert I would be supprised if the lampost`s
makers/designers chose photo sensitive device that
worked on specific wavelengths, but yes the lampost
needs to switch with daylight.

There must be a delay circuit
in them to stop the lights flickering on and off when the light level
is hovering about the switching threshold

"TeaTime" wrote in message
...
"JohnDH" wrote in message news:45832c5f.0@entanet...

Does anyone know what type of pointer is best? I've been looking on ebay
and there's loads. Red, Green, Any thoughts?

Cheers John DH
The photocell used to control street lights is chosen to peak on normal
sunlight, so green would be a much better choice than red.



Green it is
I just need to find where the sensor is. The one outside my house
doesn't seem to have anything obvious, so I guessing a sensor must be on
another lamp which controls a group.

Cheers

John DH