I spotted this photoswitch on eBay and had to take a look at the guts (search photoswitch if the link doesn’t work since eBay links go stale after a short time). I now see that the same unit is sold in multiple variations which are 24V and 220V. Not sure I would feel safe with 220 on this thing though. I am curious if the 10 ohm resistor is the only difference between the versions. If someone has one of the other versions leave a comment to let us know what the difference is. These are selling for $3.39 which included free shipping from China to Canada! Hard to believe how tilted the scales are here, I wouldn’t be able to ship this within my city for $3.39. The unit is powered from 12 volts AC or DC, it also switches the same power to the third output wire when activated. The circuit is using a 555 for operation. When the photocell goes from light to complete darkness the relay activates in 3 or 4 seconds. You can view full resolution images here.
   