[cmerli]

So I have been playing around with a some used PIRs and I think I have learned a few things but I just want to confirm. I am working with 12V PIRs and have 12V actuators or 12 V LEDs hooked to them. First I noticed if I tried to directly hook the PIR to the actuator that the PIR triggers over and over again even if there is clearly nothing moving (even covering the sensor does not stop it). I believe the reason is that if needs a resistor between the PIR and the actuator because the sudden change in the flow of electricity is creating a false PIR reading. Is that correct? Based on that I believe a TDL-2023 will work the best for this application. I have one TDL-2023 currently among my used lot but it seems to just always stay on so I am assuming it has just failed. If anyone has any insights or links to more learning material i would greatly appreciate your input.

 

[J-Man]

Typically a PIR is only used to trigger a controller which then controls the devices. Directly connecting a PIR to the device usually isn't practical.

 

[cmerli]

In this case I was actually looking for something very simple. The PIR would trigger an actuator. The movement would ring a small bell and then I would set the PIR for a very short recovery. I did not need a more complex sequence. Because of the set up I do not even care if the kids just sit there and trigger it a bunch of times. Is there a reason it would not work this way. I always enjoy your comments J-man you have great insights on prop building.

 

[JW Halloween]

It would be very helpful if you could post a photo of the sensor you are working with and either a photo or sketch of the circuit you have created.

 

[J-Man]

Well it really depends on the PIR you are using. If it has additional circuitry built in that allows adjustable "on" time, and it has an internal relay with dry contacts for connecting the actuator. If it's just a PIR only, it probably won't suffice.

 

[cmerli]

The circuit

Here are some pictures
A close up of the back of the PIR. The blue square is the time adjustment.

This is the front

This is the circuit I was using as a test. In this case the light is always on although I turned the dial down as low as it would go. (should be 1 second). In the final product I would replace the 12 V LED with a actuator

 

[J-Man]

Can't really tell what the connections are but there certainly is not a relay with dry contacts in that circuit board. As for the LED in your test staying on, PIR's need about 60 seconds to calibrate each time it's powered up. There needs to be no human or animal movement in the PIR field of view during that 60 second warm up for proper calibration. Not sure if you're doing this.

 

[J-Man]

I found a 12v PIR on ebay that looks similar to yours and it appears to have a MOSFET for switching on the load. Specs state that the load can be up to 4A. What's the current draw of your actuator?

 

[JW Halloween]

In theory it looks like it would work but what kind of actuator are you are using and what are you using as a power supply? Also the information sheet that I found on the web indicated that turning the pot will adjust the minimum delay time between triggers, not how long the output goes high after motion is detected.

 

[cmerli]

It is a door lock actuator. I tested it with the multimeter and got 3.5.

 

[J-Man]

3.5A should be within the output specs. Here is what the ebay listing states as to the delay setting, it should be the output voltage "on" time according to this:
Automatic Induction: When people enter into the range of induction, it will output a voltage equal to input voltage, after the delay time, it will output 0V; during the delay time if motion detected, the delay time will reset, and start a new delay time.
Are you allowing 60 seconds for the PIR to calibrate?

 

[cmerli]

I let it sit for more than enough time to calibrate. What I discovered was that the setting worked the opposite of what I thought. I turned counterclockwise to set a shorter time and apparently set it for the longest time. Once I turned it clockwise I got it down to 15 seconds. This still may not work since that means the actuator is engaged for 15 seconds. I noticed after a few rapid cycles it started to get warm. I may just need to go with a more traditional set up with a controller.

 

[Oak Lane Cemetery]

I used a very similar one in my monster in a box and you are correct - the adjustments turn axe backwards from what intuition would tell you to. Counterclockwise is + and clockwise is - . I was able to get my run time to around 5 seconds by slowly (VERY Slowly) tweaking the duration knob down. Mine simply interrupts the 12v supply to my motor, speaker and lights. What was getting warm on yours the actuator or the PIR?

 

[J-Man]

I let it sit for more than enough time to calibrate. What I discovered was that the setting worked the opposite of what I thought. I turned counterclockwise to set a shorter time and apparently set it for the longest time. Once I turned it clockwise I got it down to 15 seconds. This still may not work since that means the actuator is engaged for 15 seconds. I noticed after a few rapid cycles it started to get warm. I may just need to go with a more traditional set up with a controller.

Yeah, without a controller, if someone stays in the PIR field of view, the actuator is gonna stay energized.

 

[cmerli]

I used a very similar one in my monster in a box and you are correct - the adjustments turn axe backwards from what intuition would tell you to. Counterclockwise is + and clockwise is - . I was able to get my run time to around 5 seconds by slowly (VERY Slowly) tweaking the duration knob down. Mine simply interrupts the 12v supply to my motor, speaker and lights. What was getting warm on yours the actuator or the PIR?

The actuator got warm.