door closer
although springs can be used to close doors automatically, it is easier tocontrol the speed and force of closure by using the pulley principle.
the mass of the counterweight can be adjusted to produce just the right
touch for cabinet doors, entry doors, or fence gates
nylon string, small eyescrews, and any sort of weight may be used to construct
this simple yet useful device.
I also use a simple circuit to know at all times if my door is locked. A wire is connected to the metal of the lock mechanism. Another wire connects to a small metal spring inside the deadbolt hole. One wire connects to a 12-volt power source (I use an old computer power supply for this). From the power, a wire leads to several LED Xmas lights in series. So I can see my indicator from various rooms, the wire goes from one cluster to the next. One of them is outside the front door. The other wire completes the circuit. The entire circuit is in series, so that none of the bulbs gets full power. They all share the 12 volts, and will last a long time.
in addition, it is easy to add indicators if you need to know whether the
door or gate is being opened in a remote location. a chime can be made from
two pieces of metal (many old car parts make a pleasing yet substantial tone)
an indicator lamp actuated by a mercury switch is another option.
When the weight is raised by the opening door, the mercury switch is tilted to
the on position, actuating an indicator light or buzzer.
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