Instructables

Flashing LED?

I recently took apart a flashlight, which features flashing LED's. They only have 2 leads each. One flashes on and off, and the other blue and red. I can see a small black dot inside them, is this some type of transistor? I am also wondering if there is a way to get a bi-color (3 leads) LED to flash using a transistor. What kind would i nedd, and how would i nedd to hook it up? ( diagram appreciated)

It's actually an IC wafer. It's easiest to just get a flashing LED which has this chip built in. Otherwise you need several components besides the usual resistor to make one flash.
XOIIO (author)  The Lightning Stalker5 years ago
I would, but they don't sell them where I live, and I don't want to pay $6.00 for 2 LEDs.
nfarrow5 years ago
Here is one that uses a "555 timer" very fun to use a speaker and find what sounds you get with different resistance.

http://www.electronics-project-design.com/LED-Flasher-Circuit.html
Re-design5 years ago
Here's a link
http://wild-bohemian.com/electronics/flasher.html
I got it by googling "led flasher". You should be able to find a circuit using a 3 lead led or adapt this one yourself.
Good luck.
VIRON Re-design5 years ago
That is exactly the circuit to use for that purpose, although be mindful of what the common wire is, which if it were common cathode, you would use 2N3906 PNP instead of 2N3904 and reverse the battery polarity. Blinking speed depends on the capacitors which should be 1uF for very fast to 470uF for very slow. Circuit often used for American model railroad crossing lights, and will also blink a single LED if the other one is replaced by a wire. TMI: It is also called an astable flipflop (simple logic clock), or a "multivibrator" (no clue why, except maybe it was used in a replacement for mechanical power inverters for car radios in the 1950s which had a similar name).