Hi, I hope I'm not posting to the wrong group.
I have a pretty standard touchtone desk phone and want to install a small LED light the would come on whenever anyone is on one of the other phones in the house.
What resources are there available so I can do this on the cheap??
Please respond by email if necessary.
snipped-for-privacy@sbcglobal.net
Thanks, Bill Johnson
It's OK, but sci.electronics.design might be a little better - cross-posted and followups set.
There are several circuits to do this at
Matt Roberds
.
-- Dave M MasonDG44 at comcast dot net (Just subsitute the appropriate characters in the address) Never take a laxative and a sleeping pill at the same time!!
small
phones
The good thing about this circuit is that it flashes, so it draws attenion to the LED. The bad thing about it is that it uses a CMOS part, which is susceptible to being zapped by lightning. It should have a .02uF bypass capacitor from pin5 to ground to reduce the possibility of a transient voltage spike zapping the chip. But it is still susceptible. So buy a few spare chips and use a socket, and when it gets zapped and quits working, just replace the chip. ;-)
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.