The long form:
Forty feet I've tested - properly and with reserve. The transmitter pulses with a clock NE555 as an IR diode with 3% duty cycle at 2.5 kHz, that is, for 12 microseconds, with 0.6 A (6 volts across a 10 ohm series resistance, measured with Oszi - the is okay, even cheapest IRs tolerated 1A at 10us pulse duration), which is why the entire transmitter approved nearly 50 mA - on the receiver side operates a 4-fold OPV with two dozen external components between 20 and 35 mA (with relay active) - was here So far operated expense over kit level, although the components largely in the previous millennium had its launch and with modern components here a lot more function and efficiency would be to pick up. Three chandeliers for a real COM / NC / NO one has saved itself, although the relay switches. With a jumper you change the relay outputs and thus defines the behavior, in any case, the relay upon receipt of light - that could have been handled better.
In the power supply linear regulators provide with reliable series resistors for a funny load balancing with 24 Volt power - here the price of a wide operating voltage range is paid when one does not use switching regulator. Thus, the stations but also only works from 15 volts at full power.
Courageous hobbyists can use the relay switch directly, the series resistors bridge to get full power from 11 Volt, feeding the circuit directly with 9 volts, with less demand on the range increase the LED series resistance in the transmitter (here ranges eg 1/10 current for a garage door width slack off) - This not only saves power, but also prevents stray light parallel to the actual path is a direct obstacle detection at least more difficult, because the light barrier so quasi "around the corner" peeps. This is not a specific problem of these parts.
The units easily tolerated a few degrees deviation in the assembly, the reaction rate is tolerable, but enough in any case for speed measurements or the like. As an alarm sensor or for the garage door but in any case fully sufficient. The LEDs are only for diagnosis and are not visible when the housing is closed. Should be taken seriously the recommendation that the receiver suspend direct sunlight - at least 30 cm away from my workstation lamp (with 60 watt incandescent lamp) have the receiver in any case persuaded even without the transmitter to recognize on reception. Perhaps but has here the alternating light component (mains frequency) also passed - the recipient has either way obviously not true carrier frequency detection.
One star deduction for it a plan for an excellent price-performance ratio of the total supply.
