If there was a device set up before Shabbos that every hour would send an IR (infrared) signal towards an appliance such as a fireplace to either turn it on or off, would one be allowed to cover that device with a cup to prevent the signal from activating the appliance on Shabbos? Infrared is a spectrum of light, so wouldn't covering it be okay if one is allowed to cover lights on Shabbos (the Kosher Lamp an example)?

An example of such a device is the BroadLink RM4 Mini: https://www.amazon.com/BroadLink-Cable-WiFi-Automation-Controller-RM4/dp/B0872PPSGM/

Edit: The IR is sent as a short blast of invisible light.

However I also heard that grama devices are not Halachically ordained. I don't have the source.

The Kosher Lamp:

Kosher Lamp

The BroadLink RM4 Mini which sends IR blasts:

BroadLink RM4 Mini

  • To clarify: the IR is sent as a pulse? So at the moment you covered it, it would not be emitting anything, right?
    – Damila
    Feb 26 at 2:25
  • 1
    I know that there have been a number of "gramma" devices built in the past that have used interrupting a scheduled beam of light as a mechanism to register input on Shabbat. One example is a gramma keypad, with 10 holes instead of buttons, and a beam of light that pulses underneath it every few seconds. To enter numbers, you put a stick into the hole, wait for the light to flash, put the stick into the next hole, wait for the light to flash again, etc. It seems to me that if this is allowed, your case should also be allowed, but I don't have the original sources to quote.
    – Moshe Katz
    Feb 26 at 2:28
  • A timer that uses a piece that pushes the switch (somewhat old fashioned) should be similar. Removing the piece before it hits the switch is allowed, although some raise a muktzeh issue. If so, this case would be allowed since at the time of covering there was no light emanating
    – Chatzkel
    Feb 26 at 2:45
  • I edited my question. The IR is sent as a pulse.
    – Moshe
    Feb 27 at 3:23
  • If there was a (visible) light set to flash every hour, and you stood in front of it, would there be an issue? I think the issue with the IR would be what it is activating. If you blocking the beam turns on a light, you still turned on the light, no? I don't know that the intermittent nature adds to the degree of separation...
    – BID
    Feb 27 at 4:47


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