Re: How to use Liftmaster garage door IR safety sensors for other uses?

[eeewoz50@xxxxxxxxx]

On Friday, January 15, 2016 at 10:05:38 PM UTC-5, eeew...@xxxxxxxxx wrote:
> On Monday, June 25, 2012 at 5:37:06 PM UTC-4, Bob F wrote:
> > I picked up a couple pairs of these Liftmaster 41A5034 garage door safe=
ty=20
> > sensors, which I thought I might be able to use for other sensing on my=
 homebrew=20
> > home control system. Does anyone know what voltage/current the sender n=
eeds, and=20
> > what connections the 2 wire detector needs and how it signals. They bot=
h have=20
> > white 2 conductor wire with a black line on one of the conductors.
>=20
> The way that the sensors work might be this:  The transmit module power l=
eads and the sensor power leads are connected in parallel.  The transmit mo=
dule pulses on at a fixed rate. The detector module shorts out the power le=
ads whenever it detects a light pulse from the LED module.  The control uni=
t watches for pulses on the power leads.  No pulses means the light path is=
 blocked.

Each module can have some capacitance that is diode coupled from the power =
leads to power the module while the power leads are shorted.