A very simple 555 timer Open door alarm circuit project can be designed using an linear hall effect device like in this circuit diagram . This 555 timer Open door alarm circuit is based on the TL3103 linear hall effect device used for detecting the angle of rotation. The TL3103s are centered in the gap of a U-shaped permanent magnet.
This electronic project is a piece of test equipment designed using a 555 timer circuit. It's a square wave generator with 6 selectable frequencies from 1Hz to 100kHz, incrementing in decade values .
This square wave generator electronic project is based on the popular 555 timer IC and generates six preset frequencies from 1Hz to 100khz. It has a wide operating voltage range and even provides visual indication of the output.
A very simple metal detector electronic project can be designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this electronic project requires few external electronic parts .