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Topic: [Solved] I Need To Improve Power Quality (Read 462 times) previous topic - next topic

johndey

Sep 12, 2017, 06:59 pm Last Edit: Sep 14, 2017, 09:17 pm by johndey
[Solved]My system is a motion detector alarm system.  The sensor part of the system consists of 3 SR501 PIRs which will set off the alarm if any one of the sensors is triggered.  The alarm part of the system consists of a floodlight and a horn.  The controller is an Arduino Uno.

The sensors are powered by 5 volts from the Uno.  The alarm devices are powered by 12 volts from the Vin pin of the Uno.  The Uno is powered by a 12v converter which plugs into a 110 Vac receptacle.  Power and ground are distributed to the 3 PIRs via a strip board.

The system was assembled and successfully tested in my house.  However, the system is intended to be used in my front yard.  So I moved all the hardware to a 110 receptacle that is located in the yard for exterior lights and power tools.  The yard circuit is GFI protected.  When plugged into this circuit, the system, which works perfectly in the house, is very erratic.  I suspect the problem is electrical noise.

I believe the power can be smoothed out by adding some capacitors and resistors to the 5 volt part of the system, but I don't know where to connect them, nor which sizes to use.

I have attached a schematic of my system.


Paul_KD7HB

My system is a motion detector alarm system.  The sensor part of the system consists of 3 SR501 PIRs which will set off the alarm if any one of the sensors is triggered.  The alarm part of the system consists of a floodlight and a horn.  The controller is an Arduino Uno.

The sensors are powered by 5 volts from the Uno.  The alarm devices are powered by 12 volts from the Vin pin of the Uno.  The Uno is powered by a 12v converter which plugs into a 110 Vac receptacle.  Power and ground are distributed to the 3 PIRs via a strip board.

The system was assembled and successfully tested in my house.  However, the system is intended to be used in my front yard.  So I moved all the hardware to a 110 receptacle that is located in the yard for exterior lights and power tools.  The yard circuit is GFI protected.  When plugged into this circuit, the system, which works perfectly in the house, is very erratic.  I suspect the problem is electrical noise.

I believe the power can be smoothed out by adding some capacitors and resistors to the 5 volt part of the system, but I don't know where to connect them, nor which sizes to use.

I have attached a schematic of my system.


Some detective work would help, but what exactly do you mean by "erratic"?

Disconnect all three of the PIRs. Still erratic? Connect one PIR. Now erratic? Connect the next PIR. Now erratic? Etc.

Cover one PIR. Erratic? two PIRs. Erratic. Etc.....

Report?

Paul

johndey

When a PIR detects motion, it sends out a HIGH (3.3v) signal.  Otherwise it sends out a LOW signal.  Therefore, when the system is connected and there is no motion, there should be no alarm activated.  When connected to my outdoor receptacle the system will go on and off, even though there is no motion.  The duration of the on and off periods are random.

Note that when one, or more (even all 3) PIRs are disconnected, the Uno responds as though the disconnected pin is receiving a HIGH signal, and the alarm will come on continuously while the disconnect exists.

Remember, the system works perfectly while connected to the receptacle in my house, but not to the outdoor receptacle.  That means the alarm goes off when I move my hand in front of one of the sensors, and goes off when I leave the room.

Low voltage electronic circuits are notorious for being sensitive to power fluctuations.

Paul_KD7HB

Then how far away from your device is the DC power supply? Shielded wire in the wiring?

Paul

johndey

The sensors are about 6 inches from the 5v power supply.  No shielded wires,  But then again there are no active electrical devices, that might emit electromagnetic waves, within 100 feet of the sensors.  In fact, there is more radiation in my office, where the device works, then there is outdoors.

johndey

Oops, I think this post belongs in the General Electronics forum and not this forum.  Let's consider this issue closed as far as this forum is concerned and I will enter a new post in the General Electronics forum.

johndey

My system is a motion detector alarm system.  The sensor part of the system consists of 3 SR501 PIRs which will set off the alarm if any one of the sensors is triggered.  The alarm part of the system consists of a floodlight and a horn.  The controller is an Arduino Uno.

The sensors are powered by 5 volts from the Uno.  The alarm devices are powered by 12 volts from the Vin pin of the Uno.  The Uno is powered by a 12v converter which plugs into a 110 Vac receptacle.  Power and ground are distributed to the 3 PIRs via a strip board.

The system was assembled and successfully tested in my house.  However, the system is intended to be used in my front yard.  So I moved all the hardware to a 110 receptacle that is located in the yard for exterior lights and power tools.  The yard circuit is GFI protected.  When plugged into this circuit, the system, which works perfectly in the house, is very erratic.  I suspect the problem is electrical noise.

I believe the power can be smoothed out by adding some capacitors and resistors to the 5 volt part of the system, but I don't know where to connect them, nor which sizes to use.

I have attached a schematic of my system.

Wawa

#7
Sep 13, 2017, 02:29 am Last Edit: Sep 13, 2017, 04:33 am by Coding Badly
Oops, I think this post belongs in the General Electronics forum and not this forum.  Let's consider this issue closed as far as this forum is concerned and I will enter a new post in the General Electronics forum.
This is against forum rules.

Click on the "Report to moderator" link, and ask them to move it.
Leo..

edgemoron

The VIN pin is for 7 to 12V input, current drawn from it goes through a reverse polarity prevention diode which drops 0.65V and may overheat with too much current. How much current is the 3 PIRs drawing from the 5V pin? With the regulator already dropping 7 volts, it probably shouldn't be over a couple hundred mA.

johndey


Wawa

Current draw is 65mA each PIR.
?
A SR501 PIR draws about 70uA, both active or not active.

You say the floodlight and horn are powered from the V-in pin.
What is their current draw.
There is a 1Amp (absolute max) reverse protection diode between DC socket and V-in.

A full diagram and/or pictures of the setup might help.
Leo..

edgemoron

Also, is that mains to 12V converter regulated or just rectified and filtered DC?

johndey

The specs also say the "Quiescent Current" is less than 50 micro-Amps.

johndey

Power consumption:

Floodlight:  1.7 Amp
Horn:  30mA

johndey

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