Help with LEDs, diodes, transistors, something?

[Szech]

I want to make a device that will switch the power between two LEDs... essentially flashing between them. Is this what I need?
http://www.allelectronics.com/cgi-local/SoftCart.exe/online-store/scstore/m-Switching_Diodes.html?L+scstore+hwkl6325ff5a135a+9 76577954

How would I wire this up? Can anyone give me a link to a good circuity site? Thanks in advance http://sysopt.earthweb.com/forum/smile.gif

[Graham]

Szech,

No !

What you need, if I get you correctly, is an oscillator to switch the diodes, the simplest would be based on a 555 timer (very cheap), plus a few components (also cheap).
Try this site, the page here is basically what you want, just add another diode and resistor from the out of the IC to the bottom (0V) rail, the led should be the'same way up' as the existing one.
This would flash the leds alternately, at a speed determined by the formulae shown on the page.

G
Whoops forgot the link ..... http://webhome.idirect.com/~jadams/electronics/555astable.htm

[This message has been edited by Graham (edited 12-06-2000).]

[Szech]

Thanks for the link Graham. If I understand correctly, I'm supposed to use the 555 timer, and hook it up to a counter, and hook the LEDs up to alternate numbers of the counter. Is this right?

[Graham]

No, just use it as it stands, with the extra led, and it will flash them alternately.
I will copy the diag, re-drew it and post it, address to follow.

G

[Szech]

Sorry to ask so many questions, but what's a relay?
http://www.allelectronics.com/cgi-local/SoftCart.exe/online-store/scstore/p-RLY-395.html

Thanks, you're a real sport http://sysopt.earthweb.com/forum/smile.gif

[This message has been edited by Szech (edited 12-07-2000).]

[Graham]

Szech,

<IMG SRC="http://www.hollies.org/555.gif" border=0>

You can use 12V ok.

G

[Graham]

Szech,
A relay is an electro-mechanical device used to isolate or switch higer voltages/currents than the drive circuitry can handle.
You apply a relatively small current to the coil and this closes the contacts (like a switch), these can pass much higher currents.

E.G. in the circuit we are talking of, you could substitute a relay for the led and it would operate and release at the rate the led flashed, but... with a suitable relay you could switch you whole house lighting on and off (extreme example).

G

[Szech]

OH!!! Now I get it!!! I thought I was going to have to hook up a NOT gate to the OUT, and have one of the LEDs be negated. This makes much more sense! Let me double check that I have this down right... When the current is flowing through one LED, lighting it up, the other LED has either positive at each end or negative at each end, therefore it will NOT light up. Is that right? I don't have any experience with circuitry outside of some theory classes on it, so this is all new to me.

Thanks a LOT Graham, I really appreciate it.

[Graham]

You got it !!

Anytime

G