Electronic – PIR Detector Controller IC

A boost regulator is not useful here. The problem is that your module, based on the BISS0001 PIR IC, the output pin is VCC (3.3v) 10mA max. Connecting a boost regulator to this output would be really limited.

All you need is a single transistor.

^{simulate this circuit – Schematic created using CircuitLab}

Problem is that you need a transistor that works on the current provided from the output pin. Normally you see a 1k or 2.2k resistor on the board from Pin 2 of the BISS00001 to the output pin, which means only 2ma or 1.2ma at the output pin.

So you need either 1) a Transistor with a HIGH HFE or 2) a Darlington Pair (Two transistors in a pair).

^{simulate this circuit}

These numbers are all based on the transistor you choose. A 2n3904 is only 100mA to 200mA max, with a hfe of 30 (So it multiples the base current, 1mA by 30, and that's the maximum current you get at the collector, 30mA).

You need to know how much current your led box needs, and what voltage it can use. I also assumed that your two batteries are in series.

See this page http://www.electrobob.com/fun-with-leds/ for a project that does both LDR and PIR for leds (but not the same way as what I think you want).

Adding the LDR as a night time detector is simple, and also requires a transistor.

^{simulate this circuit}

Q1 and Q3 can be any weak small signal transistor (2n3904 100mA), Q2 should be a better one depending on your led box current needs (2n2222 1Amp). Adjust R2 for sensitivity.

That module is based on the common BISS0001 PIR sensor IC. That specific module is not common, especially with 4 pin outs, but since the IC is the same, it all applies.

The On Time, Off Time, and Trigger Mode are handled by a few pins on the IC.

On Time is handled by pin 3. The resistor(s) and capacitor connected to it determine the time. The Formula is Tx in Seconds ~= 24576 * Rx in kΩ * Cx in µF * 0.001.

Off Time is similar, and handled by pin 6. Ti = 24 * Ri * Ci * 0.001.

Most Likely, Rx is R14 while Ri is R13, on your board. Cx is C9 and should be 0.01 µF, while Ci is C10, and should be 0.1 µF. Check with a multimeter or magnifying glass, it shouldn't be hard to trace this circuit.

Next is Pin 1, A (Trigger Mode). If connected to Ground/Low, it will not retrigger while it has already detected motion, It ignores further movement until the IC goes through it's On AND Off time. If connected to VCC/High, it will retrigger, so it will restart the ON time. It stays on until movement stops.

If you want to use the module to just detect movement for you, on a quick read, you need to do 3 things:

1. Change Rx to a lower value. Something like 1kΩ should give a 0.2 seconds On Time.
2. Change Ri to a lower value. Something like 100kΩ should give 0.24 seconds Off Time.
3. I recommend setting the Trigger Mode Low, so that it will only detect motion once every (On Time + Off Time). If it's set to high and continues to detect motion, your Arduino will need to figure out that it's continuous motion instead. More logic.

As for the CDS Pin, a CDS is a Photoresistor. A photoresistor is typically used to bring pin 9 Inhibit low when there is sunlight. It's normally used as the lower part of a voltage divider. Why it's changing state when the module detects motion is WEIRD. This means it's either wired to something else, there is a short or break in the module, or it's mislabeled. You will need to check the circuit for it. Here is a general schematic for these types of modules, but not your specific one, for reference.