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 [...]
Water High level Alarm
This can be used as an alarm when filling overhead tanks. Quite some time ago, I used it as an indication when the municipal water used to start flowing to my pipeline. When I built this project, happiest one was my mother. Municipal water used to be pumped in the midnighl at unearthly hours and [...]
Resistors
Resistors are measured in ohms, and have a wattage rating. Resistance value is marked on the resistor in an internationally accepted color code. Normally quarter-watt resistors are used in the following circuits unless otherwise specified. Carbon film and metal film resistors are generally used. Wire wound resistors are used for higher wattage resistors.
