This is a flasher circuit that works using negative resistance and only requires a few parts.No IC required. You could make it for under a dollar not including the battery.  Using the Esaki effect takes advantage of the fact that a bipolar transistor has a PN junction between its collector and emitter. When connected in reverse biased at 12V the PN junction breaks down, (like a zener doide) and dumps the charge stored in the cap. Thereby producing a flash. This will work with virtually any general bipolar NPN transistor (not a mosfet0. The transistor may as look as though it is backwards in the circuit. Yes, it is supposed to be that way to work. The base of the transistor is not connected. The capacitor could be a lessor value but be careful. Have fun!

Note: I used just a 10 or 20k resistor so that the flashing would be slow enough to see.



Maybe I should have taken a longer video. For some reason the youtube uploader messed up the video. I will try to put a better one later. Note Google uploaded time sliced the videos and messed them up.

With lights turned off.



Make four of these circuits and use a one pole three way switch for turn signals on a bike or child's car.

More information:
http://en.wikipedia.org/wiki/Negative_resistance

Note: since this works with 10-12v. you could easily adapt this for a car or motorcycle.

Other uses for such a circuit:
Pictures from: http://users.tpg.com.au/users/ldbutler/NegativeResistance.htm