On Mon, 21 Mar 2011 10:17:13 -0700, Smitty Two
wrote:

In article
,
Harry K wrote:


For what it's worth, my liftmaster has an "intelligent" button. *It
connects with just 2 wires that power it and it sends signals back
down the two wires on top of the power to the controller to raise and
lower the door, to lock the door, and to activate the light. *So no
ordinary push button is going to work on mine. *Just saying there are
others out there.- Hide quoted text -

- Show quoted text -

Ya, riiightt. You can test that theory by disconnect the wires at the
switch and touching them together. Prepare to be embarrassed.

Harry K

You and Tony have both scoffed at James' post, but I see nothing wrong
with it. Haven't seen such a gadget, but it'd be duck soup to make a
control panel that has multiple buttons for different functions, still
with only two wires connecting the control to the operator head. Each
button sends a coded signal down the power wires, said signal being
demodulated at the far end.
I agree. I have a Genie that has the traditional start/stop button
plus a light on/off button (that doesn't move the door) plus a lock
slide switch that prevents the radio receiver from working. All with
just two wires. I assume it uses resistors to differentiate between
the controls rather than a fancy digital system, but who knows - with
cheap pic-type microprocessors available, they could have done it many
different ways.