Cheap & Easy Motion Detectors/Night Light Controllers (Picaxe or Stand-alone)

mikeyBoo

Senior Member
#1
hi folks,
See attached pdf. I've used a lot of these gadgets around the house for turning on night lights & sensing motion (driveway etc.). If using with a Picaxe, leave out JP & pull the Picaxe input high with ~10k...100k resistor. Pickup distance ~25 feet. You can power it with +5v if you like.
You can use as a standalone +12v LED strip light control by installing JP & powering from +12v (of course don't hook output to Picaxe).
I use them for my boat sheds with a 12v battery kept charged by a solar cell & regulator.
Note that they can be rigged for always or night-only operation.

Oops! See SR501 Labels.pdf for duplex box (USA style) drill template (ignore pushbutton holes (for another board))
Also terminal strip labels included
 

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mikeyBoo

Senior Member
#2
Rev C (Adds Flash & a few other Options)

Added a few options to make motion detector more useful:

Basic Operation: A simple motion detector with option of night-only activation. Once motion is detected, the device
will turn ON an open-collector output with option of flashing or steady-ON for up to 3.5 minutes.
Very low quiecient current so suitable for battery operation, use onboard or external voltage on the
output. Output is DC only, so to activate a 120vac circuit you will need a DC relay.
The primary purpose of this project is to allow the SR501 motion sensor to be used with higher-voltage systems
(e.g. +5...+32vdc) via an open-collector transistor. The previous design (Rev B) works fine but there were a few options
I wanted to add to Rev C:

01 Added jumper J1 to remove power from the timer chip (TLC555CP) when Flash mode is not needed. This will
save some battery power when in activated mode.

02 Added jumper J2 to allow enable/disable of onboard LED. Some applications (e.g. a security system) may want to
hide the location of the motion sensor. This would also save some battery life when in activated state.

03 Added jumper J3 to allow selection of Flash or On when activated. Flash mode is useful when using the motion
detector as a night-time alarm (e.g. a boat or car alarm). Note that a switch can be wired to J3 to allow easy
switching between modes (e.g. ON OFF FLASH).
Also, note that the Flash mode is useful for critter control (to scare off squirrels, rabbits, etc. from garden, sheds
or birds in attic, barn roof, etc. You can add a beeper when in flash mode to help scare ‘em off.

TAKE NOTE: If you wish to activate a Picaxe (to send RF code, etc.) you should run the SR501 board on +5v or less
(e.g. 3 AA batteries) or make sure a +5v or +3v regulator precedes the Picaxe chip.
The values shown for C5 & R4 can be changed if a shorter or longer flash is desired. For example, reducing C5 to
.01uF would produce a very brief (strobe-like) pulse of light. The default values were chosen because I wanted the
option of adding a beeper (for scaring critters off my boats, lawn building, & workshop attic).
As always, I’m open to suggestions.
 

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mikeyBoo

Senior Member
#3
Expander Board (up to 6 PIR sensors) for SR501 Rev C Host Board

hi folks,
This is simply an expander board for SR501 PIR modules. Allows connecting up to 6 SR501 sensors to the
SR501 Rev C Host Board described in previous post.
This was taught to me by squirrels: (they figured out how to avoid the North/South sensors)
In an attic or under a floor it helps to see in 4 different directions, a sensor triggered on any (up to 6) sensor will activate the motion or alarm output.
Also added a safe 3v output for use by a Picaxe or other uProc regardless of the host board power source (usually +12v).
(I'm gonna' beat them critters yet!)
 

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lbenson

Senior Member
#4
Thanks for this. I had not realized that the PIR modules were open collector--I was getting ready to use a separate input for each, when I only needed to detect motion in any direction.
 

mikeyBoo

Senior Member
#5
Thanks for this. I had not realized that the PIR modules were open collector--I was getting ready to use a separate input for each, when I only needed to detect motion in any direction.
Good morning,
Don't think the SR501 PIR modules are open-collector. They output a +3v level when activated. That's why the little expander board has them ORed through diodes.
The host board described in post 2 (that a PIR plugs into) is open-collector.
Hope that makes sense (I'm still on my first cup of coffee).
 

hippy

Technical Support
Staff member
#6
I must admit that I am not clear what components or modules we are actually talking about; PIR sensors themselves, boards they may be fitted on, or other boards they may be connected to.

Part of the problem is that "PIR" can refer to anything from the sensor component through to an off the shelf unit which connects to a burglar alarm system.

Some pyroelectric infra-red sensor component seems to be effectively 'open emitter', from the source of a high-side FET -

https://www.allelectronics.com/mas_assets/theme/allelectronics/spec/D203S.pdf

Modules which use sensors such as HC-SR501 seem to often be based around the BISS0001 which does have a high-low op-amp comparator driven output but could be made open collector or diode mixed.
 

mikeyBoo

Senior Member
#8
I must admit that I am not clear what components or modules we are actually talking about; PIR sensors themselves, boards they may be fitted on, or other boards they may be connected to.

Part of the problem is that "PIR" can refer to anything from the sensor component through to an off the shelf unit which connects to a burglar alarm system.

Some pyroelectric infra-red sensor component seems to be effectively 'open emitter', from the source of a high-side FET -

https://www.allelectronics.com/mas_assets/theme/allelectronics/spec/D203S.pdf

Modules which use sensors such as HC-SR501 seem to often be based around the BISS0001 which does have a high-low op-amp comparator driven output but could be made open collector or diode mixed.
hi Hippy,
Yep, unfortunately there are a lot of "flavors" of PIRs. What my postings refer to are specifically the "SR501" PIR sensors which are very cheap & available & work great. The modules output +3v when active, Lo when not.
The "host board" I refer to in posting 2 turns the SR501 sensor into an open-collector device that can use a greater range of voltages (e.g. +12v as used with many alarm systems or +5v as used with Picaxes).
The "expander" board in post 3 plugs into the "host board" & allows using multiple SR501 sensors with a single host board (e.g. as used in an open room/attic where you want to "see" in 4 directions at once).
I put pictures of the host board & SR501 sensors in the attached .pdfs (sometimes a picture is worth a 1000 words).
Hope that makes it clearer.
 
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