Beeps if you leave open the door over 20 seconds This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 presents a high resistance (up to 200K) thus [...]
rs232+serial+port+isolator+schematic
Quad 2 Input CMOS IC 4011 Timer Circuit Timer circuit can be used to switch OFF a particular device after around 35 minutes. The circuit can be used to switch OFF devices like radio, TV, fan, pump etc after a preset time of 35 minutes. Such a circuit can surely save a lot of power. [...]
12 volt Wind Turbine It is possible to use a 12V DC motor (I assume its a car starter motor) as a wind turbine generator to provide energy conversion between the mechanical torque from the wind rotor turbines, (called the prime mover) and the connected 150V load. A gearless two or three bladed upwind wind [...]
A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale current of the meter movement. So, if you have a 1 milliamp meter and you want to read 0-10 volts you will need a total resistance [...]
One of the things you may not think about when buying a new laptop is what will happen if you lose your laptop AC adapters. Sure this does not seem like something you would lose, but it is very easy to misplace. So it is always a good idea to know where to buy another [...]
