Portable Electric Lamp cum LED Flasher

Here's the circuit of a portable type flasher uses 25W, 230V AC bulb and nine LEDs. The bulb and led's glows alternatively. The circuit includes a 555 timer based astable multivibrator which generates a square wave. This output drives the transistor bc547 to riger the gate of lamp controller triac.

Simple Duophone System

Here a simple circuit diagram of duophone that allows you to access two telephone line through a single telephone set. The conversation through each line will entirely private when the conference switch in the dual phone is off. So this duophone circuit has a unique feature of talking to two people simultaneously what is called three-party telephone conversation/conference facility.

Pyroelectric Fire Alarm

Ordinary fire alarm circuits uses diode sensors to detect fire presence. But a pyroelectric fire alarm circuit described here is an ultra-sensitive fire sensor that uses direct piezoelectric property of an ordinary piezo element to detect fire.

FM Booster Circuit to Receive Far Away FM Stations

This is a low cost FM booster circuit to receive far away fm stations clearly on your radio in your local area. The circuit diagram of FM booster consist of a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570.

Solar Charger Circuit For Lead acid, Ni-Cd And Li-ion Battery

The solar panel based charger described here is capable of charging Lead acid, Ni-Cd And Lithium-ion batteries. This circuit diagram is designed for a solar panel which is capable of delivering 5W power. The solar panel outputs 16.5V. It can deliver a current of 300-350 mA.lead acid, Ni-Cd and Li-ion. The lead-acid batteries are commonly used in emergency lamps and UPS.

LM317 Constant Current Battery Charger Circuit

The LM317 is an adjustable three-terminal positive-voltage regulator which can be used as a constant current source for battery charging. This regulator IC is capable of supplying 1.5 A over an output-voltage range of 1.25 V to 37 V.

Touch Sensitive Musical Bell With Timer

This circuit diagram is a UM66 based touch sensitive musical bell. The circuit is built around CMOS IC CD4011 and popular melody generator IC UM66. The circuit contains a pair of touch plates. When these are bridged by hand for a moment, the um66 starts making music. Moreover this circuit has a timer which stops the music automatically after a few seconds. This makes the circuit, an automatic music bell.