The simplicity of the WSPR receiver described here makes it attractive as a low cost radio propagation tool.
Tired of being blasted off your seat by excessive audio volume when you switch television channels or when the commercials come on? To mitigate such unnerving changes in program audio, a popular automatic volume controller from the vacuum tube era was updated to today's technology. This circuit is also useful in home recording.
Leave your garage door open? No problem! This handy device will close it automatically for you. (Plus, you don't even have to remember to replace batteries in this unit.)
Now you can do things like listen to music on your laptop with the lid closed because volume control is now accessible externally.
by Jeff Eckert
Find out how to upgrade your iPad 2 with a keyboard case, take 4-D photos, and if Bing is losing big (it is), along with other pretty interesting stuff.
Fundamentals For Beginners
Build a Variable Timer
This is an adjustable timer circuit.