----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
Some US company (I forget who) made an ultrasonic
remote controlled valve
TV
where the remote was essentially tuned metal bars that
were mechanically
hit when the button was pressed. No electronics in the handset at all.
The receiver in the TV detected one of 4 (or so) different frequencies
corresponding to the 4 buttons on the remote, and then operated a relay
to trigger the appropriate function (I think channel selection was done
using an electromechanical stepping swtich, etc).
Boy, that brings back memories. We had one of these sets when I was in
high-school.
I believe it was a Zenith, though I wouldn't swear to it. I used to get a
kick out of clicking
the buttons just to hear the sounds. You are correct in that the channel
selection was
electro-mechanical. It was also a very loud mechanism.
This type of remote control is also where the term 'clicker' came from.