Tag Archives: indicator

Simple Water-Level Indicator-Cum-Alarm

Schematic Diagrams      Comments Off on Simple Water-Level Indicator-Cum-Alarm

This water-level indicator-cum-alarm circuit is configured around the well-known CMOS input-compatible, 7-channel IC ULN2004 Darlington array. As the water level rises in the tank, it comes in contact with probes P1 through P7 and thereby makes pins 7 through 1 high, sequentially. As a result, the corresponding output pins 10… Read more »

Water Level Indicator Circuit Schematic

Schematic Diagrams      Comments Off on Water Level Indicator Circuit Schematic

Simple, two-wire, remote monitoring unit, Three-LED level display, 9V battery powered The whole project was developed on a friend’s request. Its purpose was to remotely monitor the water-level in a metal tank located in the attic by means of a very simple control unit placed in the kitchen, some floors… Read more »

Mains Indicator

Schematic Diagrams      Comments Off on Mains Indicator

It is not always immediately obvious whether a power-consuming appliance is switched on or not. Examples are the lamp in the attic or the shed, or electric heating in an awkward place. A nice solution would be to connect an LED directly in series with the appliance, unfortunately you’d better… Read more »

Isolated Fuse Fail Indicator

Schematic Diagrams      Comments Off on Isolated Fuse Fail Indicator

This circuit uses standard components and shows a method of indicating the fuse status of mains powered equipment while providing electrical isolation from the mains supply. A standard miniature low power mains transformer (e.g. with an output of around 6 V at 1.5 VA) is used as a ‘sense’ transformer… Read more »