Here is the circuit I would recommend to light an LED when the signal input is at or near ground and will extinguish the LED when the input is at or near + 5 VDC. It would provide minimal loading on a microprocessor output signal.
73 - Jim W5ZIT --- On Fri, 9/25/09, tait700 <[email protected]> wrote: From: tait700 <[email protected]> Subject: [Repeater-Builder] Busy Signal (COS) inverter Circuit. To: [email protected] Date: Friday, September 25, 2009, 6:33 AM Hello, Was wondering if someone knowledgeable would be able to advise me on the best way to proceed with this, I need to extract a signal to power a normal LED that indicates when the Mute has opened on a Receiver. The Receiver has a "Busy" line coming from the Micro that supplies 5V DC when the mute is closed ( Quiet ) and goes to OV when the Audio is open ( Audible ) I don't have any further info on the current available from the micro and am a little dubious about running a small SPDT relay off this signal. I searched the RB site and found the article concerning the "maxtrac cor buffer" which uses a Transistor to invert the logic but am not sure how to apply this to a LED ( 20ma ) and whether the resistor on the Base input would be the right value. If i could do this without risking the health of the micro ( which controls everything on the Board ) i would be very happy. Any info would be most appreciated, Regards, __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
