6V / 9V / 12V Battery Charger with Constant-Current Charging

This is the circuit diagram of battery charger which has many important features such as current-constant charging, overcharge protection, short-circuit protection, deep discharge protection and more. The constant-current charging is a popular method for lead-acid and Ni-Cd batteries. In this circuit, the battery is charged with a constant current that is generally one-tenth (1/10) of… Read More »

Cheap Motorcycle Alarm

This is simple to build and cheap motorcycle alarm circuit which could be fitted in motorcycles to take care of them from getting stolen. The tiny circuit may be hidden anyplace, without having any difficult wiring. Practically, it fits all motorcycles as long as they’ve a electric battery. It is not going to drain out… Read More »

Long Range/Distance Infrared Transmitter

Here the long range/distance Infrared transmitter circuit, give you extra power for your Infrared transmitter. The majority of the IR remotes do the job reliably within a range of 5 metres. The circuit complexity increases in case you design the IR transmitter for good operation more than a extended distance, for example, 10 metres. To… Read More »

Automatic Switching-on Emergency Light

Automatic Switching-on Emergency Light The schematic diagram shown right here is the automatic switching-on emergency light circuit which is controlled using IC. The most important capabilities of this circuit are: automatic switching-on of the light on main power failure and battery charger with overcharge protection. When mains electrical power is absent, relay RL2 is in… Read More »

DC Motor Speed Controller

This is the schematic diagram of DC motor speed controller circuit. The circuit applies two oscillators/timers which are connected as a Pulse Width Modulator (PWM). The timer chip which applied in this circuit will be an nmos dual timer/oscillator NE556. This timer IC has two 555 timers in a single 14-pin IC package.

Pyroelectric Fire Alarm System

This is definitely an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo component to recognize the fire. The lead zirconate titanate crystals within the piezo component have the property to deform and produce an electrical potential when heated, thus converting the piezo component into a heat sensor. The circuit mentioned… Read More »