LED to indicate garage door is open

Thread Starter

oxicottin

Joined Jul 4, 2008
20
Hello agian, I have another question about SgtWookies first drawling. I searched the net and found what direction the diode would go but I cant figure out the direction of the led light. I know the LED has one long lead and one short lead but what wire should I soldier to which lead? thanks!
 

Thread Starter

oxicottin

Joined Jul 4, 2008
20
I found a picture.... BUT I noticed the arrows on the LED are pointing in the different direction from what sgtwookie posted in his drawling? Why?

 

Thread Starter

oxicottin

Joined Jul 4, 2008
20
Bill, acually I have read threw it fast and the only thing I can find is that if a device is light-activated (meaning that incoming light stimulates it), then the symbol will have two small arrows pointing toward it but what about one arrow pointing away?
 

SgtWookie

Joined Jul 17, 2007
22,230
I found a picture.... BUT I noticed the arrows on the LED are pointing in the different direction from what sgtwookie posted in his drawling? Why?
The symbols for the LEDs were just drawn a little differently. Don't let that confuse you. The main thing is that the little arrow(s) are pointing away from the body of the diode, which means that they emit light when current flows through them.

If the little arrow(s) pointed toward the body of the diode, then it would be a photodiode. Photodiodes change resistance according to how much light is shone on them; they do not emit light.
 

Thread Starter

oxicottin

Joined Jul 4, 2008
20
Shew.......I searched the net for that symbol and couldn't find anything. Hay SgtWookie what would I do if I wanted a green light if the door was closed and a red light if the door was open?


Thanks,
Chad
 

Wendy

Joined Mar 24, 2008
23,415
You could use something like this...

555 Schmitt Trigger

Part of the art of electronics is to take existing designs and modify them to what you want them to do. I'm not sure this would work with the power supply you are using as I last saw it, but as long as it doesn't exceed 15V it will work, even if it is noisy (lots of hum).



This can be modified to match the work you've already done, I'm putting it up by way of example.
 

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SgtWookie

Joined Jul 17, 2007
22,230
It would be easier to just change the type of switch, and move things around a tad.

Like this:


The upper schematic is the same as before.
The lower schematic has a different switch, the resistor and 1N4004 diode moved to the other side of the switch, and a green LED added.
 

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