Identifying a IC

[Supreme920]

good day everyone,

Long time viewer of the EEV channel, but never joined the forum. Today is the day

I have spent the last our trying to identify a IC chip on a cheap PIR motion detector, but no luck so far. The goal is to extend the timer, default time is between 10 seconds and 15 minutes. I want to increase it to approx 3 or 4 hours. I thought it might be a simple RC circuit, and I would just add a capacitor to extend the time. However it seems its controlled by an IC. The marking on the IC in only 12-9 in a SO14 package. Not so help full marking...

The middle pin from the time potential resistor is connected to pin 11 (the via is below the IC)
Pictures are here:
https://mschinkelshoek.quickconnect.to/mo/sharing/xgUK8QVMK

If more information is needed let me know!

Your help is much appreciated, mainly by our rabbits, who will get a infrared lamp for heating in the winter time, triggered by their movement

[ledtester]

A simple solution is to have the PIR sensor's relay trigger a relay timer like this one:

https://www.amazon.com/DROK-Controller-Delay-off-0-01s-9999mins-Switching/dp/B07DFT2WDS/

[Supreme920]

Yes that is good alternative, however, its outside, and i wanted to keep it as simple and robust as possible, therefor I was hoping to use IP44 rated product. Your solution would mean an extra 5V supply as well.

I do appreciate your thinking outside the box solution! And i keep it as a backup plan!

[ledtester]

Instead of changing the capacitor you can try swapping out the resistor (i.e. the potentiometer) responsible for setting the time.

15 mins to 4 hours is a factor of 16. So if the timer pot is a 10K maybe change it for a 200K pot.

Long RC timers are not always that reliable but it might work.

Be careful in there - you're working with a mains powered circuit!

[Supreme920]

Thanks for the suggestion, but I am wondering if it is an RC circuit, or if the resistor is just an input for the setting in the IC. that is why I was hoping to find the datasheet.
But I will test it out, take out the pot and add a bigger resistor.
Thank you for your input.

[NE666]

I was hoping to use IP44 rated product. Your solution would mean an extra 5V supply as well.

You might consider a mains powered timed relay variant, and mount in in a suitably IP rated exterior DIN enclosure. This is how I hold my garden lighting on for an hour after sunset, once the supply is activated by a dusk 'till dawn time switch.

https://www.amazon.co.uk/dp/B07WFM671V

[moffy]

If you have a scope you can look for a clock signal, and if you find one, if by varying any capacitors nearby you can modify the frequency.

[ledtester]

If you have a scope you can look for a clock signal, and if you find one, if by varying any capacitors nearby you can modify the frequency.

It looks like it powered by a capacitive dropper supply... (see attachment).

[moffy]

If you have a scope you can look for a clock signal, and if you find one, if by varying any capacitors nearby you can modify the frequency.

It looks like it powered by a capacitive dropper supply... (see attachment).

Might be dangerous hooking a scope up if powered from mains, so best to use a bench supply for the investigation. Or are you implying that it counts mains cycles for timing? Not sure what you mean, it still needs a clock if it is some sort of logic/micro, which it looks like, could be internal or external clock, if external then modifying it might change the timing.

P.S. The big blue cap looks very much like a capacitive supply cap.

[ledtester]

If you have a scope you can look for a clock signal, and if you find one, if by varying any capacitors nearby you can modify the frequency.

It looks like it powered by a capacitive dropper supply... (see attachment).

Might be dangerous hooking a scope up if powered from mains, so best to use a bench supply for the investigation. Or are you implying that it counts mains cycles for timing? Not sure what you mean, it still needs a clock if it is some sort of logic/micro, which it looks like, could be internal or external clock, if external then modifying it might change the timing.

P.S. The big blue cap looks very much like a capacitive supply cap.

I think it is dangerous to have a beginner use an oscilloscope on a capacitive dropper powered circuit.

[moffy]

I think it is dangerous to have a beginner use an oscilloscope on a capacitive dropper powered circuit.

That is a good point, I sometimes assume the target audience is experienced.

[m k]

Make a piggypack extended timer circuit.
Or replace the whole original one.

How's the time adjusted?
It can still be RC, 150k pot and one elco.