Need LED Flasher help - Page 1
Forum section: electronics / general

author: NickMak
author_rank: Newbie
timestamp: September 28, 2012, 05:24:38 pm
content: Hello All,I am new to the blog along with making circuts although it has always interested me I finally have some $$ to play around with.What I am trying to make is a circut that will flash about 20 of the below LEDs. This is my first project so please go easy on me. Would like to use a 9volt battery (maybe 2 since I heard they don't last long) WHat is a good flasher to use?ThanksNickLED:Size: 5mmForward Voltage (V):DC3.2~3.4Forward Current (mA):20View Angle: About 25 degreeLuminous Intensity: 5000-7000mcdLens Color:Water ClearEmitting Colour:BlueResistance Value : 470 ohm&220 ohmPower Rating : 0.25WResistor Tolerance : +/-5%-

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 28, 2012, 07:01:55 pm
content: There are a lot of ways to blink LEDs. The circuit you use depends a lot on how you want each individual LED to behave. Are all of the LEDs going to blink simultaneously? Or individually? Or in groups?So far as the battery goes, you would get more juice out of 4 AA batteries.

author: NickMak
author_rank: Newbie
timestamp: September 28, 2012, 08:08:34 pm
content: I would want all LED to blink at once ( have all led on at same time off at same time) Prefer a fast blink. After a small bit of research I have found a 555 chip that looks like it would help, is that right?

author: FJV
author_rank: Regular Contributor
timestamp: September 28, 2012, 08:50:35 pm
content: Is trying a simple led flasher and using 1 or 2 transistors to "beef up" the signal enough for lighting 20 leds an option?http://wild-bohemian.com/electronics/flasher.htmlhttp://www.retrospieler.de/e-flashbutton.html

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 28, 2012, 08:56:02 pm
content: Yes, the 555 is probably a good IC for this particular application. It will make generating the on/off signal easy.The next thing to decide on is the system voltage you'll be using since this will determine how many LEDs can be put in series.Then you will need to solve how you will drive that many LEDs from the 555 IC. A 555 timer can source or sink 200mA so you may or may not be able to drive all those LEDs directly from the 555's output. If it were me, I wouldn't push my luck. I would use one or more transistors to drive the LEDs. The 555's output would then just need to drive the transistors' gates and/or bases which would be much less of a load for the IC.

author: NickMak
author_rank: Newbie
timestamp: October 01, 2012, 07:29:15 pm
content: Awsome, Thanks for all the help. I will let you all know how it works out and what I finally decide to try .ThanksNick

author: NickMak
author_rank: Newbie
timestamp: October 01, 2012, 07:53:05 pm
content: Can I use relays where the LEDs would go ?

author: TerminalJack505
author_rank: Super Contributor
timestamp: October 01, 2012, 08:25:15 pm
content: Yes, you could do that so long as you don't need to switch the relays on and off too fast. The relays would need to have the appropriate voltage and current ratings and you would want to put a flyback diode across the relay's coil terminals.