Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
The only flashing LED I know of (i.e., running without an external circuit) is a 2.2 volt model with a peak of 4 volts. If you connect this to a 9 volt battery without a limiting resistor, it will flash only once.
Just thought I'd chuck my two penneth worth in..
The flashing LEDs I have (the only ones I can get) are happy with 3.5v to 13v. NO RESISTOR.
The internal circuitry contains both the flasher and a current limiter circuit so the resistor is not required up to 13v.