Light sensor "flashing" LED

quartzz

Looking for the simplest of gadgets, basically a "fake" security indicator (in fact there probably will be a real camera, but I'd like this too). It's the sort of thing that could probably be made DIY from veroboard. Literally a flashing blue LED in a box (not a large chunky lens, just a single, subtle, "dot" indicator), with a light sensor so it activates at night. Just needs the flashing, a battery or USB connector, and the light sensor.

It doesn't seem to be the sort of thing ebay or Amazon sell. I could almost google "DIY light sensor circuit diagram", but it would be less hassle and probably cheaper to spend £5 on a pre made product. I'll sit it on the window so it can be seen from outside

casper_gutman

Something like this, perhaps? https://www.ebay.co.uk/itm/126336735874

quartzz

gosh. precisely. that looks reassuringly homemade (that wasn't meant as sarcasm). I could probably hook a light sensor up to that as a sort of bolt on.....

or even this https://www.ebay.co.uk/itm/405715138842

Section62

quartzz said:

gosh. precisely. that looks reassuringly homemade (that wasn't meant as sarcasm). I could probably hook a light sensor up to that as a sort of bolt on.....

or even this https://www.ebay.co.uk/itm/405715138842

Do you need two LEDs or would one be enough?

I think the module casper_gutman found has two LEDs and the circuit to make them flash alternately... if you only needed one flashing LED then one with an inbuilt flasher chip would be cheaper and probably use less power.

E.g. this one is £2.59 for one, £3.99 for 5, with a choice of colour and size.

https://www.ebay.co.uk/itm/264491231909

It needs 12V, but if you are installing a real CCTV camera (with a 12v supply) then you could probably just supply the LED from that.  TBH running the LED from a 12v adaptor already in use for the CCTV would probably draw so little power that the running costs would be cheaper than anything using batteries.

Also, running the LED 24/7 is likely to use less than running a separate light sensor circuit to turn it on and off....  does it need to be turned off in the day?

quartzz

tbh ideally (the other link I found) a USB connector for power (can hook it into a 3 pin mains adapter), the "off during the day" isn't absolutely essential....it would just be a polished way of doing it. a slow second on/second off flash would be fine. the "off during the day" might actually give more of an impression of it being a "real active" monitoring system.

I've actually ordered a couple of those keyfob LED's linked above in blue, I'll see how they work out.