Author Topic: Keyless entry remote fob anti theft Idea (Read 2625 times)

guest8810 · « **Reply #15 on:** January 27, 2020, 05:13:06 PM »

Quote from: culzean on January 27, 2020, 03:46:48 PM

In my experience a Faraday cage does not need to be earthed with low power signals, in high power shielding they are earthed, but mainly for safety to stop a charge build up on the surface of the cage. The idea with a Faraday cage is that the external signals are routed around the outside conducting material and leave a void inside with no electrical charge. Any opening in a Faraday cage needs to be no larger than 1/8 of the shortest ( highest frequency ) wavelength you are trying to block ( that is why you can see inside a microwave even with door closed because the door has a metal screen with thousands of tiny holes punched into it, light can get through but not longer the wavelength length electrical waves ). Domestic Microwaves work on around 2.5Ghz, and keyless entry works on about 433Mhz, so if the high power ( 900 watts + ) microwaves cannot get out of the microwave cabinet, there is no way the low power 433Mhz ( measures in Milliwatts ) is gonna get in, earthed or not.

Copper or Mumetal or even aluminium works very well for faraday cage, because it is good electrical conductivity
rather than magnetic properties that you are looking for.

Thank you for this information not being of the required intelligence quota to understand all this. May I still insert my Fobs into the microwave plugged in or out.
It is a-tin box after all so must be better than nothing, how about the fridge in fully insulated container to stop cold inference there now a whole set of further observations to be investigated

guest8810 · « **Reply #16 on:** January 27, 2020, 05:14:35 PM »

Quote from: sparky Paul on January 27, 2020, 05:05:45 PM

Just use an old tobacco tin, that will do the job.

Here's another trick I use, being the forgetful type. If you walk away and have forgotten to lock your car, but then find you've walked too far and are out of range, touch the fob to the side of your cranium and press the button. It might eventually fry your brain, but extends the range of the plipper considerably.

Must you earth the old tobacco tin as well ?

culzean · « **Reply #17 on:** January 27, 2020, 05:24:38 PM »

Quote from: sparky Paul on January 27, 2020, 05:05:45 PM

Just use an old tobacco tin, that will do the job.

Here's another trick I use, being the forgetful type. If you walk away and have forgotten to lock your car, but then find you've walked too far and are out of range, touch the fob to the side of your cranium and press the button. It might eventually fry your brain, but extends the range of the plipper considerably.

+1 with the very low power signals we are talking about an un-earthed tobacco tin is more than enough.

Does touching the fob to your head only work if you are looking at the car LOL