Tamper proof safety circuit

I am using some UV-C LEDs in a design, and as these emit dangerous radiation, I am looking for a circuit that will rapidly blow the diodes if access is gained. It would need to retain sufficient energy for a few weeks after any power is removed, but needs to be a small as possible. The plan would be to destroy them if: - Power is removed for more than a week (after the unit having been first used) - Stored energy is dropping below a threshold that ensures destruction - Access is detected I am thinking capacitive discharge, but any comments appreciated on other approaches!

by barryn56
July 11, 2020

There are many possibilities. One of them is to fill the box, air tight, with extra pressure and if a hole is made, the pressure drop, and an internal membrane may detect it. As far what it could do, I could try to erase the code of the MCU, when the pressure drop occurs, as example, rather than bombing or electrocuting the circuit, since I could then re-load the program if it was just a mistake. Because I would try to use an MCU, such as the MSP432 from TI, which can go into a sleep mode drawing few micro-amps, in quiescent mode, even in the nano-amp range, and which can easily wake up from an external signal, such as a raising edge of voltage. Back to the membrane, either it is piezo electric (so its movement generates the electrical pulse which will awake the MCU), either it closes a loop implying a charged capacitor which will then try to discharge itself when the electrical loop is completed (a capacitor holds its charge when NOT part of a loop, but an internal resistance is a leak to each and every cap. Just need a cap which has a very low leakage). I repeat, that is just ONE of MANY possible scenario. But overall, try to have one which can handle and gently recover from honest human mistake, if possible.

by vanderghast
July 12, 2020
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