Adding lights to random things in your house is great fun for kids of all ages. Adding solar lights to random things in your house is even more fun. Adding red eyes to a piggy bank to make it evil is probably the most fun you'll have all afternoon.
I found this piggy bank at my local Dollar Store and instantly knew he'd look great with evil red eyes. I could have gone the simple route and wired the eyes to a power adaptor, but where would the fun be in that?
In the end I made a simple light detecting solar circuit that fits inside the pig. I'll stick him in my classroom next week and see if the kids notice him.
This is cheap to put together, easy to build, and long lasting. (Also, you don't have to stick this circuit into a pig. It'll work with anything.)
Container (In my case a $1 piggy bank)
Two Red LEDs (For this project they need to be red)
Two 100 ohm resistors (or 50 ohm works as well)
Two AAA or AA rechargeable batteries
One AAA or AA battery holder
One solar cell with a power greater than 4 volt
One blocking diode (1N914)
One PNP transistor
One 5,000 ohm resistor (or close to it)
I also used two 5mm LED mounts, but you might not need them.
Hot Glue Gun
Time: 30-60 minutes.