Security lights controlled by alarm system

Thread Starter

J de Beer

Joined May 6, 2017
7
I am a pensioner in South Africa with a little knowledge of electronics. I please need some help with the following:

I have a Texecom alarm system with 10 PIR sensors inside and outside my house installed. I want to activate my security lights when any of the outside PIR sensors detect movement at night (it will also work when the alarm is activated). I have measured the voltages at the alarm control panel and find that when a PIR is not detecting movement, the voltage is 2.6V DC and when a movement is detected the voltage is 6.6V DC. I have tried to construct a circuit with CircuitMod, and tried to build a test circuit without success. I believe the transistor must only be activated at 6V and not at a lower voltage. The circuit is attached with the info I have. The circuit must be added to the existing alarm system without any negative effect to the system.

Is there anybody out there that can please help me with this project? I will be very grateful.
 

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Thread Starter

J de Beer

Joined May 6, 2017
7
PIR_Pyronix KX15DQ.jpg PIR_Lince Bobby.jpg PIR_Optex vx402.jpg
Welcome to AAC

We would need to know the PIR model.
A picture is sometimes useful too.
Thank you for the quick response. I have the following PIRs installed:
1X Pyronics KX15DQ
5X Lince Bobby
2X Optex VX-402 (not the "rec" like the picture shows)
I have attached pictures of each.
 

Picbuster

Joined Dec 2, 2013
1,040
I am a pensioner in South Africa with a little knowledge of electronics. I please need some help with the following:

I have a Texecom alarm system with 10 PIR sensors inside and outside my house installed. I want to activate my security lights when any of the outside PIR sensors detect movement at night (it will also work when the alarm is activated). I have measured the voltages at the alarm control panel and find that when a PIR is not detecting movement, the voltage is 2.6V DC and when a movement is detected the voltage is 6.6V DC. I have tried to construct a circuit with CircuitMod, and tried to build a test circuit without success. I believe the transistor must only be activated at 6V and not at a lower voltage. The circuit is attached with the info I have. The circuit must be added to the existing alarm system without any negative effect to the system.

Is there anybody out there that can please help me with this project? I will be very grateful.
I understand that you want a contact / signal when voltage goes to 6.6V. ( or just above 2.6V?)
this is easy to build with a few component however I need first an answer to question above.
Picbuster
 

Thread Starter

J de Beer

Joined May 6, 2017
7
I understand that you want a contact / signal when voltage goes to 6.6V. ( or just above 2.6V?)
this is easy to build with a few component however I need first an answer to question above.
Picbuster
Thank you for tying to help me - I appreciate it very much.
I think if the voltage is 6V and more the contact/signal must be made. I have tried to install 8 to 9 diodes in series to the base of the transistor and in the CircuitMod program it seems to work, but if I build the test circuit it does not work. My knowledge is not enough to get the right solution and I don't want to damage my alarm system with a wrong solution.
 

KMoffett

Joined Dec 19, 2007
2,918
Move the relay coil and diode from between the transistor's emitter and common, to between the +12v and collector. Now put your string of seven or eight diodes between the emitter and common.This should raise the turn-on voltage to greater than 4V.

Ken

Not: you would also have to change the relay to a 6VDC version.
dendad's would would be better.
 
Last edited:

dendad

Joined Feb 20, 2016
4,219
Try something like this...PIR light switch.jpg
The series LED drops about 2V, and the diodes another .7V so the transistor should not turn on at rest. If it does, add another diode(s) in series.
Sorry about the quality drawing;)
 

Thread Starter

J de Beer

Joined May 6, 2017
7
Thank you for the help. In my town there is no suppliers of electronic parts. I must use what is available in old electronic boards etc. Else I must order parts on the internet and the postage costs more than the parts! I will try the solutions and post the final workable solution. I appreciate all the help.
 

Thread Starter

J de Beer

Joined May 6, 2017
7
dendad's circuit should be able to be made from local electronics junk.

Ken
Good day to all

I want to thank you all for your inputs. I have used DenDad’s proposal and I used 4 – diodes in series to bring down the voltage to a workable value. The result of the circuit is attached and it works 100%. I have also connected a Universal Timer Control to the circuit to switch off the security lights after a predetermine time.

My next step will be to replace the switch in the 12v circuit with a LDR so that the circuit will be automatically armed/activated when it is dark and disabled during day time. My biggest problem is to get hold of a Light Dependant Resistor in my part of the country.

Thanks again
 

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dendad

Joined Feb 20, 2016
4,219
I'm pleased to be of some help :)
In stead of an LDR, can you get any old toys or garden lights that have a solar cell in them? If so, you could use the voltage generated by the cell to turn a transistor on that then disables the other circuit. There are quite a few ways to detect light, even to using an LED as a light detector.
 

Thread Starter

J de Beer

Joined May 6, 2017
7
I'm pleased to be of some help :)
In stead of an LDR, can you get any old toys or garden lights that have a solar cell in them? If so, you could use the voltage generated by the cell to turn a transistor on that then disables the other circuit. There are quite a few ways to detect light, even to using an LED as a light detector.
I will try that, thank you so much.
 

Thread Starter

J de Beer

Joined May 6, 2017
7
Good day to all you brilliant people.
With your help my system that controls the security lights via the security system is 100% functional for a long time.
I have only one problem and I hope someone can assist me. When the LDR switches on when it gets dark, Relay X close and supply power (12v) to Relay Y to switch on the security lights - if one of the PIR sensors detect movement. I have noticed that when the LDR switches on (Relay X), then Relay Y closes for about a second (the security lights flashes for a second).
What can I do to prevent the unnecessary activation of Relay Y. I have attached a picture of the circuit. Please forgive me if it does not look "professional".
Thanx in advance for any help.
Enjoy your day.SecurityLights2018.png
 
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