idea for creating Touch sensitive wire strip like variable resistor

Well, there is not much variation in voltage along a copper wire unless it is drawing a LOT of current, so I don't see how.

Bob

 

That's partially true. One leg can be commited to ground leaving only one conductor as the capacitive pickup. I think it might be prone to false triggering though.

Chris

 

A bunch of them here.

http://discovercircuits.com/C/capacitance-sw.htm

Chris

 

Stumbled across this the other day while looking for something else (as is always the case)..might be of interest.
http://www.hpi.uni-potsdam.de/baudisch/projects/touch_using_time_domain_reflectometry.html

 

If you're looking for a simple finger bridging circuit that demonstrates where along a resistive divider your finger has bridged the circuit you can put this together. I show a 9V battery and an Ammeter but a basic Ohmmeter will work just as well. Placing your finger across any of the 4 touch points will give a different Ammeter or Ohmmeter reading.

Chris

 

Are you referring to SWR?

Chris

 

Yes, but this does not hold true for transmission lines properly terminated in it's characteristic impedance at both ends. In this case the only differences from input to output should be dielectric and radiation loss. Usually,the more expensive the transmission line the less one should see in either regard.

Chris

 

Steve, brain fart on this end! Yes, you're absolutely correct and so was Toy. My last post I was still stuck on SWR, which is better described and stated as Reflected Power. It has little to do with Toy's theory.

Yes, that's how antennas work!

Chris