Using SPT Photoelectric units to light a light

Thread Starter

CompletelyUnsure

Joined Jun 16, 2020
4
HOLD ON THIS FOR NOW - I messed up my measurement notes so have to retake them and come back...

Firstly, new to this type of thing so if I ask silly questions just point me to the place to learn my errors!

I bought some of these from Home Depot, which in retrospect seems like a terrible idea based on reviews from other sites. They seem to have the same unit repurposed on Amazon and titled "Cop Security 15-946". My goal is to use these to trigger a light if the beam is tripped but so far that's not working. I've put it on a multimeter and the signalling seems odd to me so I was hoping to get some education here.

TESTS
In all tests the device is powered by a 12v 5mah battery wired direct to the unit and the mulitmeter is set on DC voltage test
TEST1
** Multimeter positive lead attached to unit signal wire. Multimeter ground lead attached to battery ground.
*** In non-alarm state, reading is 3.6v
*** In alarm state, reading jumps to about 4.1v but settles back to 3.6v
*** At times (inconsistently) when rapidly removing the item I'm using to block the beam the voltage will drop to 0.3v before returning to 3.6v

TEST2
** Multimeter ground lead attached to unit signal wire. Multimeter positive lead attached to battery positive
*** In non-alarm state, reading is 3.6v
*** In alarm state, reading jumps to about 4.1v but settles back to 3.6v
*** Every time, when rapidly removing the item I'm using to block the beam the voltage will jump to 13+v before returning to 3.6v

I also tried to find the manual on google before I did all of this, but of course that's nowhere to be found. I suspect this might just be a concept I'm unfamiliar with but I can't find the right search terms or material to learn about it. Happy to do a lab too, as I learn better hands on!
My end goal is to light a standard light bulb with it when triggered, perhaps multiples of them eventually through a more complex board like an arduino or pi with a series of these sensors if possible, but first I have to figure out what the heck this signal wire is actually doing
 
Last edited:

Thread Starter

CompletelyUnsure

Joined Jun 16, 2020
4
I didn't realize there was an edit timer, so reposting here with correct information:

Firstly, new to this type of thing so if I ask silly questions just point me to the place to learn my errors!

I bought some of these from Home Depot, which in retrospect seems like a terrible idea based on reviews from other sites. They seem to have the same unit repurposed on Amazon and titled "Cop Security 15-946". My goal is to use these to trigger a light if the beam is tripped but so far that's not working. I've put it on a multimeter and the signalling seems odd to me so I was hoping to get some education here.

TESTS
In all tests the device is powered by a 12v 5mah battery wired direct to the unit and the mulitmeter is set on DC voltage test
TEST1
** Multimeter positive lead attached to unit signal wire. Multimeter ground lead attached to battery ground.
** In non-alarm state, reading is 3.5v-3.8v
*** In alarm state, reading maxes at ~4.3v but settles back to original range
*** At times (inconsistently) when rapidly removing the item I'm using to block the beam the voltage will drop to 0.3v before returning to 3.6v

TEST2
** Multimeter ground lead attached to unit signal wire. Multimeter positive lead attached to battery positive
*** In non-alarm state, reading is 3.5v-3.8v
*** In alarm state, reading maxes at ~4.3v but settles back to original range
*** Every time, when rapidly removing the item I'm using to block the beam the voltage will jump to 8+v before returning to original range

I also tried to find the manual on google before I did all of this, but of course that's nowhere to be found. I suspect this might just be a concept I'm unfamiliar with but I can't find the right search terms or material to learn about it. Happy to do a lab too, as I learn better hands on!
My end goal is to light a standard light bulb with it when triggered, perhaps multiples of them eventually through a more complex board like an arduino or pi with a series of these sensors if possible, but first I have to figure out what the heck this signal wire is actually doing
 

Thread Starter

CompletelyUnsure

Joined Jun 16, 2020
4
Haha, I googled around for a like a week and you found that video in no time, so thank you for that!

These are close to the units I have, mine don't have the tamper wires but everything else is very much the same. I think this highlights what's wrong, which is that I thought any of those 3 non power pins were simply signal wires but it seems to be more complicated than that. Anyone know what this means on the 3/4/5 pins? He said something in the video about being normally closed or normally open but I'm not sure I understand how to run with that information?

1592485782488.png
 

ericgibbs

Joined Jan 29, 2010
10,171
hi CU,
Look at the symbols painted on the 3,4,5 terminals.
pin#3 is the relay contact wiper {Common]
pin#4, is the relay N/C normally closed contact
pin#5, is the relay N/O normally open contact.

Do you follow OK.
E
 

Thread Starter

CompletelyUnsure

Joined Jun 16, 2020
4
Hey, that does help actually. I was able to get the wiring correct, thanks for the help! If anyone is interested, I also found this youtube video by the same guy you linked me which talks about how to wire these things up. The missing piece for me was I just didn't realize you have to jump a power wire to the N/C or N/O contact and that's how you select the setting you desire.
 
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