[Solved] I Need To Improve Power Quality

[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.

Motion Sensor Schematic.pdf (17.9 KB)

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.

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

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.

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

Paul

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.

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.

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.

Motion Sensor Schematic.pdf (17.9 KB)

Motion Sensor Schematic.pdf (17.9 KB)

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.

This is against forum rules.

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

The VIN pin is for 7 to 12V [u]input[/u], 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.

Current draw is 65mA each PIR.

johndey:
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…

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

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

Power consumption:

Floodlight: 1.7 Amp Horn: 30mA

12 Volt 2 Amp AC/DC ADAPTER POWER SUPPLY CORD 12V 2A 5.5mm/2.5mm connector tip

Charger Specification: Input voltage: AC 100-240 Volt 50-60Hz (worldwide use). Output: DC 12V 2A LED Charging indicator. Cable length: 110 cm DC Connector: Tuning Folk Head, Compatible with both 5.5x2.5mm and 5.5x2.1mm Tip: Inside positive " + " , Outside negative " - " Use High quality IC version, Short circuit protection, Overload protection. Tested Units. In Great Working Condition. All Products are FCC/CE/ROHS Certificated. Application: For Wireless Router, LED Strip, DSL Modem, Network Hub, Switch, Security Cameras

johndey: Floodlight: 1.7 Amp

You can't power that one from the V-in pin with the supply connected to the DC socket. As explained, there is a 1Amp (absolute max) diode between DC socket and V-in. The diode will burn out sooner or later. Power the horn directly from the supply (e.g. splice the cable going to the DC socket).

Do you switch the horn with a relay or mosfet. Does the horn have a diode across.

Still waiting on that full diagram, and pictures. Leo..

3 Requested photos attached

P9120100a.jpg

P9120101a.jpg

P9120102a.jpg

johndey: I will enter a new post in the General Electronics forum.

The next time you feel the urge to cross-post resist that urge.

See reply #7 for what you should have done.

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

What are the specs of your plug pack, can you post a picture of its name plate please?

Thanks.. Tom... :)

Based upon the information I received from this forum, I have removed the connection to the Vin pin of the Uno. Instead, the power supply to the alarm devices will be from a second, separate 12v brick transformer, connected to a 110 V-AC outlet. The second power supply will have a 3 amp rating.

The Uno will continue to be powered by a 12v, 2A brick transformer connect to a 110 VAC outlet.

The alarm devices will be controlled by the Uno via a 5v, 1-channel relay.

I haven’t made the changes yet since I am awaiting delivery of parts.

A schematic of the circuitry is attached.

With regards to cross-posting. Since I believe that my problem is connected with noisy power, I made my original post to the forum that had the word, “power” in its title. It was not until I began to receive replies that I realized I was appealing to the wrong audience in that forum. I looked all over the web page for a link that would transfer the posting to the correct forum, but could find no such link. Then I looked for a link that would enable me to close the issue. Again, no link was to be found. So, as a last resort, I posted my intentions in a reply.

Motion Sensor Schematic.pdf (19.1 KB)