Help needed designing electrical circuit

[SXRguyinMA]

I've been doing some searching online for this type of circuit, but they all use multiple LEDs or different input voltages.

Basically I want a ciscuit that will flash 2 5mm blue LEDs at teh same time, at a rate of 2-3 times a second. I can buy the parts and solder it, I just want to know if someone here could show me how to put it all together lol. Most of the ones I've seen use the 555 timer.


this one (http://wild-bohemian.com/electronics/flasher.html) is the closest I've found to what I want (Basic LED flasher circuit using NE555 timer IC, middle way down the page)

this one (http://www.electronic-circuits-diagrams.com/lightsimages/1.gif) uses 6v input and one LED, if it could be changed to 12v input and use 2 LEDs thatd be perfect

and this one (http://www.instructables.com/id/How-to-make-a-fast-blinking-LED-bike-light/step7/The-Electronic/) uses 9v and 7 LEDs

a HUGE thanks and +rep to anyone who can help me. Thanks!!!

[LiTHiUM0XiD3]

use the second one (6v)... step down the voltage with resistors.... or a REG... and then hook up 2 LEDs in parallel.. :)

[SXRguyinMA]

wouldnt I have to change the LED resistor if I use 2 instead of 1? anyone know what resistor I would need to turn 12v into 6v? or where I could go to figure it out?

[crenn]

If you don't change the resistor, all that will happen is the LEDs are half as bright due to the same amount of current going through the 2 LEDs.

[Oneslowz28]

Give me a few min and I will have you something.

[Oneslowz28]

Here is what I came up with. It will flash 2 LEDs at any rate you wish by adjusting the 1k pot. I am bread boarding it now to verify.

http://img229.imageshack.us/img229/7766/2ledflasher.jpg

[Oneslowz28]

Ok my design has a flaw somewhere so dont use it just yet. I am trying to figure it out now

[SXRguyinMA]

dude you rock! I'll keep watching!

based off your design I came up with this shopping list, but will update/change it as nec.

http://www.postwhore.biz/albums/userpics/10082/Untitled.png

[Oneslowz28]

Ok I can not figure my flaw out. I am going to put it aside for tonight and look at it again in the morning with fresh eyes. If anyone sees what I did wrong please point it out.

[SXRguyinMA]

this one blinks them alternately @ 3 times per second, with a 9v input. I could add a resistor to change the 12v to 9v and this would probably do the trick. what do you think oneslow?

http://www.apogeekits.com/flashing_lights.htm

http://www.apogeekits.com/images/blinkie_lights.gif

Oneslow you'll like this. Basically I'm thinking of doing an Arctic Cat themed case. I want to take 2 NGK spark plugs and smash the porcelain out of them so I'm left with the metal housing with the electrode. Then I'm going to take 2 5mm blue LEDs and put them into the housing with hot glue, and use some of the small acrylic rod I've got left to make a "spark." The I'll hot glue a spark plug cap top the top of the metal housing, and run the LED wiring through the "plug wires." This is why I want them to blink this fast. What do you think?

[r0adawg]

Think I might have found something that will work for you... the 150 ohm resistors give you about 24ma to the led's. it works from a 5v source. the 4.7 pot will allow you to adjust the speed of the blinking led's and the 555 passes about 4.5 volts to the leds

http://img709.imageshack.us/img709/7223/555timer.png (http://img709.imageshack.us/i/555timer.png/)

[SXRguyinMA]

looks pretty simple. I might swing by radio shack tonight and breadboard it up. thanks!

also, nothing connects to the CV pin?

[Oneslowz28]

CV is pin 5 and is not used in a normal flasher circuit. I can show you how to build a simple 5v power supply also if you dont want to go the resistor route and do it right with a voltage reg.

[SXRguyinMA]

well a normal ATX power supply also has a 5v connector, so that will work perfectly :up:

[Oneslowz28]

I would breadboard it but I don't have a 4.5k pot

[SXRguyinMA]

would this 5k trimmer (http://www.radioshack.com/product/index.jsp?productId=2102789)work in place of the 4.7k?

[Oneslowz28]

yea 5k is close enough

[Oneslowz28]

I would reccomend checking out http://www.futurlec.com/ as their prices are awesome. That one you linked to will be fairly large too btw. Think larger than a knob on an electric guitar.

[SXRguyinMA]

ok heres what I ended up doing. I got this kit (http://pcboard.ca/kits/led_blinky/index.html) (actually 2 of them, in a care package from my buddy John over @ www.pcboard.ca).

It accepts 8-15VDC, and with the standard 39k ohm resistors it flashes like this:

C0PUKs8tec4

here is the schematic
http://i92.photobucket.com/albums/l11/sportrider12584/Project%20Arctic%20Cat/0426001721.jpg

and parts list
http://i92.photobucket.com/albums/l11/sportrider12584/Project%20Arctic%20Cat/0426001722.jpg

in the breadboard with 39k resistors
http://i92.photobucket.com/albums/l11/sportrider12584/Project%20Arctic%20Cat/0426001826.jpg

I kept working my way down with resistor sizes, a notch or two at a time, until I ended up with 10k ohm resistors.

http://i92.photobucket.com/albums/l11/sportrider12584/Project%20Arctic%20Cat/0426001827.jpg

which ended up like this:
l_sqCHOigtg

its exactly what I wanted. so I soldered up the kit
http://i92.photobucket.com/albums/l11/sportrider12584/Project%20Arctic%20Cat/0426001850.jpg

lUAXdlTaO9o

funny how the camera makes it seem to flash, then steady, then flash

now for the super hard part....figure out how to get the porcelain out of the metal shell of a spark plug. 2 of them actually. I may end up making a mold of a spark plug and use some casting epoxy to cast them, then finish them with the dremel. I've got a good hour into trying to chip out the porcelain with a hammer and small chisel, and its HARD

also, what is a good free program to use to design electrical circuits?