Water-Level Indicator

Here’s a simple water-level indicator for overhead tanks that uses three LEDs (LED1, LED2, and LED3) to indicate minimum, middle, and maximum water levels in the tank. The sensor probes comprise A,...

ULTRA-BRIGHT LED LAMP

This ultra-bright white LED lamp works on 230V AC with minimal power consumption. It can be used to illuminate VU meters, SWR meters, etc. Ultra-bright LEDs available in the market cost...

Garage Light and Security Control

Useful for vehicle owners, this gadget automatically turns on indoor/outdoor garage lights and raises an alert when an automobile enters the garage. Assume switch S2 is in ‘on’ (closed) state. When power...

LED Sand-Glass Timer

This circuit (Fig. 1) simulates the old sand-glass timer. A total of 32 LEDs create the effect of sand grains passing from the upper half of sand-glass to its lower half. When...

PWM-Based Speed Control for DC Motors

There are several methods for controlling the speed of DC motors. One simple method is to add series resistance using a rheostat. As considerable power is consumed in the rheostat, this...

Intelligent Water Pump Controller with Water-level Display

Most of the circuits for multi-level indication/control of water in tanks employ a bunch of wires running between the circuit and the overhead tank, which accounts for almost half the cost...

Infrared Proximity Detector

This proximity detector using an infrared detector (Fig. 1) can be used in various equipment like automatic door openers and burglar alarms. The circuit primarily consists of an infrared transmitter and...

Precision 1HZ Clock

This precision 1Hz clock uses just two ICs and one junction field-effect transistor (JFET) in conjunction with a commonly available crystal and a handful of other passive components. The Pierce-type crystal oscillator...

INTRUDER RADIO ALERT SYSTEM

Consider a situation where a burglar has entered your house and snapped the telephone wires, leaving you with no means of communication with the outside world. In such an emergency, you...

FLASHING BEACON

A flashing beacon has many uses. It can be employed as a distress signal on highways or as a direction pointer for parking lots, hospitals, hotels, etc. Here we present a...