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From: wolfgang@wsrcc.uucp (Wolfgang S. Rupprecht)
Newsgroups: sci.electronics,comp.sys.ibm.pc.hardware
Subject: Re: Simple one evening project
Keywords: IBM, PC, floppy drive, LED, in use, color, density
Message-ID: <1990Oct30.152843.2922@wsrcc.uucp>
Date: 30 Oct 90 15:28:43 GMT
References: <1990Oct23.162706.10585@elroy.jpl.nasa.gov< <4748@bwdls58.UUCP>
Organization: Wolfgang S Rupprecht Computer Consulting, Washington DC.
Lines: 25

>Well, Radio Shack (here) only sells the two-lead type of bicolor LEDs.
>With these, the direction of current flow determines the LED color.
>Any gurus out there who'd be willing to post an equally quick&clean 
>circuit for performing the same function with this two-lead type of LED ?

Yea. I'll bite.  The simplest solution is if you have a spare 1488
rs-232 driver.

		 +12v
	   1488   |
		 |\			 Red-Green
	---------| >------/\/\/\/\--------(LED)-----+
		 |/	   1k 1/4w		    |
		  |	   			    V gnd
		-12v


This will drive the led with about +/- ~8 ma.  Change the resistor to
470 ohms to increase this to 16ma if you want and your led likes this
much current.

-wolfgang
-- 
Wolfgang Rupprecht    uunet!wsrcc!wolfgang (or) wsrcc!wolfgang@uunet.uu.net
Snail Mail Address:   Box 6524, Alexandria, VA 22306-0524