DS

Although this alarm is designed to protect valuables left in a tent, it can also be used as a baggage alarm (either on or in one‘s bags) and in similar situations. The tent alarm can be triggered by many different sensors. One is a current loop, connected to pin PB4 of an ATtiny13 micro-controller: this could be a thin wire which would be broken by a prospective pilferer caught off his guard. Alternatively, it can be a reed switch contact normally held closed by a magnet, arranged so that the budding burglar will accidentally move the magnet and thus open the contact. This could be used to protect a door or a zip fastener securing a tent. Another sensor connected to PB4 is an LDR (light dependent resistor). If the LDR is left in a dark place (such as under a sleeping bag) the thief will trigger the alarm if he moves the bag to expose the sensor to light. The resistance of the LDR is about 100 kΩ in the dark and just a few ohms in the light. If only the light sensor is to be used, the...