a home made electronics question; How do I make a gadget that allows for tonal recognition?

Posted by roger houston | Engineering | Wednesday 13 January 2010 9:23 pm
O.G. asked:


In the pursuit of intellectual curiosity I have been exploring how to make a number of gadgets. I want my next gadget to do this: Recognize one or multiple specific tones and connect different circuits depending upon the tone heard.
Does anybody know a good site to find easy guides? Or perhaps some suggestions of a common object that I can take and modify to make it do what I want?
Thanks

How do you make a electronic gadget with a hinge?

Posted by roger houston | Engineering | Sunday 6 September 2009 1:38 am
twinsenw asked:


I want to make an electronic gadget with a hinge (specifically an audio keyboard which can fold in half). How do you connect the wires to the two halfs over the hinge without crimping the wires? I’d like the wires to not be visible… if they were inside the hinge that would be great.