The very old, early consumer TV remote controls used ultrasonics. They
used the principle of small hammers striking some little metal bars
inside. Each bar was resonant at a particular frequency. The receiver
would follow its command according to the frequency it was recieving.
These remotes are no longer available. The same is for many of the
remotes for the early models of sets. The next generation of remotes
used IR (infared). They tranmit the command data over an IR beam. All
the new remotes are using IR for their data transmission.
There is a newer generation of remotes that will be coming on the
market in a few years. These are going to be using 2.4 gHz RF (radio
frequency). The data will be sent on an RF carrier. This is going to
soon be low in cost for the manufactures to achieve. It will also be
able to through walls, and around corners, because it is RF, and not
optical as like the IR type transmission. Each TV set will be able to
address its own security code, so that there will not be any conflicks
or crosstalk.
The best place to find the very old remotes are at the flea markets.
Sometimes you can find them at a garage sale. The only problem, is
that it has to be the right one for your set. I tell people that since
the prices are very cheap at the flea markets, they should buy a
number of them when possible. This way there will be parts to make one
out of a number of them.
--
When I was about 8 years old, I saw a remote control TV for the first
time. This was very facinating for me. This was back in the 1950's.
I told my father that I wanted a remote control TV set also. He went
out and bought a long broom stick and a rubber disk. He cut some slats
in to the rubber disk to fit to the TV's channel selector, and volume
control. He also beveled the sides to be able to work the fine tuning.
He then fastened the disk on to the end of the broom stick.
When we were sitting in the easy-chair, we could now change the
channels, and adjust the volume without getting up. It was a true
mechanical remote control! No complications, and no batteries.
By-the-way, he earlier wired a power switch next to where we were
sitting, so we can turn the TV on and off. In those days the TV sets
did not have any computers or digital circuitry that required standby
power. A TV set was like a light bulb. When the power was shut off, it
was really turned off.
Jerry G.
========