Laser alarm

A

AK

Guest
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"
 
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"
Click to expand...

Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
Click to expand...

Thanks.
 
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
Click to expand...

I got the lasers in and hooked it up for 5 minutes.

I liked that it's beam is adjustable.

It did not heat up.

Will post when I get the detector parts in. Will show what I have BEFORE I apply power. :)

Andy
 
On Thursday, May 2, 2019 at 12:17:45 PM UTC-5, AK wrote:
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

I got the lasers in and hooked it up for 5 minutes.

I liked that it's beam is adjustable.

It did not heat up.

Will post when I get the detector parts in. Will show what I have BEFORE I apply power. :)

Andy
Click to expand...

I found this. It uses less parts and does not seem to be missing info that the other project did.

What do you think?

"https://makezine.com/projects/laser-tripwire-alarm/"

Andy

https://makezine.com/projects/laser-tripwire-alarm/
 
On Thu, 2 May 2019 19:00:41 -0700 (PDT), AK <scientist77017@gmail.com>
wrote:

On Thursday, May 2, 2019 at 12:17:45 PM UTC-5, AK wrote:
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

I got the lasers in and hooked it up for 5 minutes.

I liked that it's beam is adjustable.

It did not heat up.

Will post when I get the detector parts in. Will show what I have BEFORE I apply power. :)

Andy

I found this. It uses less parts and does not seem to be missing info that the other project did.

What do you think?

"https://makezine.com/projects/laser-tripwire-alarm/"

Andy

https://makezine.com/projects/laser-tripwire-alarm/
Click to expand...

I'd question the use of red tinted glasses if one is using a red
laser. (that's the color you want to keep out of your eyes)

I wouldn't use a cadmium sulphide photocell, because they are prone to
water damage unless they are hermetically sealed in glass. The type
he shows just has a film of varnish or epoxy to protect the element
and the performance of those degrades over time and humidity. I'd use
an NPN two terminal photo-transistor. (emitter to ground)

You'd want some power supply if you intend to leave it on 24/7

It would be fine for a simple easy project. If the object is to learn
it is ideal.
 
On Friday, May 3, 2019 at 6:31:52 AM UTC-5, default wrote:
On Thu, 2 May 2019 19:00:41 -0700 (PDT), AK <scientist77017@gmail.com
wrote:

On Thursday, May 2, 2019 at 12:17:45 PM UTC-5, AK wrote:
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

I got the lasers in and hooked it up for 5 minutes.

I liked that it's beam is adjustable.

It did not heat up.

Will post when I get the detector parts in. Will show what I have BEFORE I apply power. :)

Andy

I found this. It uses less parts and does not seem to be missing info that the other project did.

What do you think?

"https://makezine.com/projects/laser-tripwire-alarm/"

Andy

https://makezine.com/projects/laser-tripwire-alarm/

I'd question the use of red tinted glasses if one is using a red
laser. (that's the color you want to keep out of your eyes)

I wouldn't use a cadmium sulphide photocell, because they are prone to
water damage unless they are hermetically sealed in glass. The type
he shows just has a film of varnish or epoxy to protect the element
and the performance of those degrades over time and humidity. I'd use
an NPN two terminal photo-transistor. (emitter to ground)

You'd want some power supply if you intend to leave it on 24/7

It would be fine for a simple easy project. If the object is to learn
it is ideal.
Click to expand...

Like this ?

"https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&freeText=NPN+two+terminal+photo-transistor&langId=-1&storeId=10001&productId=1108144&krypto=yvMRfiqT5kazbX%2BCkKh1uA2mPOgKbZ3LJsKMBhS83W0tbPxSQvZxsjX5QjStsxqgog2qLjVLrLfZpldXshuCZNiOCg3GnMFmkwFkkWaGXXM%3D&ddkey=https%3AStoreCatalogDrillDownView"
 
On Fri, 3 May 2019 06:44:22 -0700 (PDT), AK <scientist77017@gmail.com>
wrote:

On Friday, May 3, 2019 at 6:31:52 AM UTC-5, default wrote:
On Thu, 2 May 2019 19:00:41 -0700 (PDT), AK <scientist77017@gmail.com
wrote:

On Thursday, May 2, 2019 at 12:17:45 PM UTC-5, AK wrote:
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

I got the lasers in and hooked it up for 5 minutes.

I liked that it's beam is adjustable.

It did not heat up.

Will post when I get the detector parts in. Will show what I have BEFORE I apply power. :)

Andy

I found this. It uses less parts and does not seem to be missing info that the other project did.

What do you think?

"https://makezine.com/projects/laser-tripwire-alarm/"

Andy

https://makezine.com/projects/laser-tripwire-alarm/

I'd question the use of red tinted glasses if one is using a red
laser. (that's the color you want to keep out of your eyes)

I wouldn't use a cadmium sulphide photocell, because they are prone to
water damage unless they are hermetically sealed in glass. The type
he shows just has a film of varnish or epoxy to protect the element
and the performance of those degrades over time and humidity. I'd use
an NPN two terminal photo-transistor. (emitter to ground)

You'd want some power supply if you intend to leave it on 24/7

It would be fine for a simple easy project. If the object is to learn
it is ideal.

Like this ?

"https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&freeText=NPN+two+terminal+photo-transistor&langId=-1&storeId=10001&productId=1108144&krypto=yvMRfiqT5kazbX%2BCkKh1uA2mPOgKbZ3LJsKMBhS83W0tbPxSQvZxsjX5QjStsxqgog2qLjVLrLfZpldXshuCZNiOCg3GnMFmkwFkkWaGXXM%3D&ddkey=https%3AStoreCatalogDrillDownView"
Click to expand...

Sure, any one of those. The only downside is that your beam aiming
has to be more precise (smaller target)

R2 will probably be on the order of 4,700 - 10,000 ohms and NOT the
100 ohms he's suggesting. Putting in at the end of a tube to exclude
ambient light would be a good idea too.

A professionally designed "break-beam" detector would use a modulated
light source and a detector that is able to discriminate the
modulation frequency, as a way to exclude false detection.

What he's showing is similar to how it was done since the days of
vacuum tubes. The thing will work fine as long as the laser light is
significantly brighter than any ambient light.



Do you have a "bench" power supply and a digital multimeter? I'd
consider those necessary basic stuff for this project. You can use
any "wall-wart" power supply or a battery pack for power but there's
some inexpensive half-way decent power supplies on Ebay.
\
This one is a good one (I just assembled one for a project of mine)
https://tinyurl.com/y5xtx7zm

They claim 2 watts at 15 volts but I wouldn't trust that, the
transformer seems too small to me. It is a kit too...
Easy to solder, the board is "masked." The component placement is
silk-screened onto the board. The board is marked for a 100 ohm
resistor and the schematic says 240 and 240 is what is supplied, but
other than that, there's not much to go wrong.

digital multimeters go on sale at Harbor Freight for ~$3.00

Only caveat, don't switch through the current settings while connected
across a power supply - that burns out the meter's fuse. (I had a
smart high school grad working for me who went through several before
he caught on - he had zero experience or training but was able to
build stuff and read schematics, so I gave him projects he could
handle)
 
On Friday, May 3, 2019 at 10:26:27 AM UTC-5, default wrote:
On Fri, 3 May 2019 06:44:22 -0700 (PDT), AK <scientist77017@gmail.com
wrote:

On Friday, May 3, 2019 at 6:31:52 AM UTC-5, default wrote:
On Thu, 2 May 2019 19:00:41 -0700 (PDT), AK <scientist77017@gmail.com
wrote:

On Thursday, May 2, 2019 at 12:17:45 PM UTC-5, AK wrote:
On Tuesday, April 30, 2019 at 12:49:08 PM UTC-5, Phil Hobbs wrote:
On 4/29/19 11:39 PM, AK wrote:
I was looking at this.

"https://blog.prayogindia.in/make-laser-light-security-alarm/"

Would this be an acceptable LDR?

"https://www.jameco.com/z/CDS001-8001-Photocell-100mW-150Vpack-3Kohm-Max-Light-0-2Mohm-Min-Dark_202403.html"


Cad sulphide cells aren't used much anymore--I'd stick with a
photodiode. If you modulate the laser and detect the AC, it'll work
well day and night, unlike a CdS cell.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com


Sure, any one of those. The only downside is that your beam aiming
has to be more precise (smaller target)

R2 will probably be on the order of 4,700 - 10,000 ohms and NOT the
100 ohms he's suggesting. Putting in at the end of a tube to exclude
ambient light would be a good idea too.
Click to expand...

I will mount it in a piece of pvc. Will adjust depth and check the resistance.


What he's showing is similar to how it was done since the days of
vacuum tubes. The thing will work fine as long as the laser light is
significantly brighter than any ambient light.
Click to expand...

With the detector in a tube, the laser will be quite a bit brighter.

The beam is adjustable from a fine point to a wide beam.

Do you have a "bench" power supply and a digital multimeter? I'd
consider those necessary basic stuff for this project. You can use
any "wall-wart" power supply or a battery pack for power but there's
some inexpensive half-way decent power supplies on Ebay.
Click to expand...

I have both.

My buck converter is adjustable.

Andy
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top