basic electronics

This tutorial is intended to cover the creation of a single-sided PCB based on an existing layout. For information about creating a layout, you should seek tutorials elsewhere. I regularly use this method and have great success, easily handling traces 10 mils wide, surface-mount parts, etc.
Etching
Print the pattern on the full side of the [...]

This circuit works with battery 9V a piece is very small. For the work happens independently don’t be under house electricity. The circuit will make a noise to warn work as soon as , detect which be switch model usual close the circuit or aluminium , eliminated separate.

In the circuit basically usability base IC UM66T use sound of music sweet-sounding origin and be usable easily. It use just integrated one circuit and a loudspeaker , Piezo-Buzzer , the small-sized , and have power supply 3V only. The detail is other of integrated number this circuit.
The UM66T [...]