Electronic Lock
Here is an electronic code lock, which can be used as a door latch or key for ignition, etc. Operation is fairly tricky and there lies the beauty of the circuit. There are a number of switches, actually nine, which should be operated in a particular and owner – configured -sequence, or else the circuit [...]
Lie detector circuit
Here’s a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when [...]
capacitors
Capacitors store a bit of electrical energy and come in many types and varieties. Capacity is measured in terms of Farads named after the great scientist Michael Faraday. As farad is too large a value for most general applications, microfarads (mfd) and nanofarads (nf) are normally used in hobby and consumer applications.
Ceramic, polyester, paper, mica, [...]
Half Wave Power Supply
Half wave rectification is simplest, as it requires only one transformer, one diode and one capacitor, but we have added a LED to give power supply indication. A simple half wave rectifier for 12V is shown below
500mA transformers are generally used for these circuits. Connect the primary wires to the mains chord after carefully insulating [...]
