Night Lamp From Scrap CFL

Night Lamp From Scrap CFL by AR



MILIND M. SUTAR, JEEVAN S. GHODAKE AND PROF. P.B. JOSHI

Compact fluorescent lamps (CFLs) are available in different shapes and power ratings. These consist of an electronic ballast circuit and a programmable-logic-controlled tubelight. Most CFL manufacturers offer a guarantee of half a year on their product.

In an unserviceable CFL, the filament has reached the end of its life but there is every possibility that the electronic ballast circuit inside the bottom of the CFL is in working condition. The night lamp circuit described here uses the serviceable electronic circuit fitted in the base of an 11-watt CFL.

Fig. 1: An efficient night lamp circuit
For constructing this night lamp, remove the CFL glass tube and replace it with four white LEDs as described below. You should be careful not to break the tube as it contains hazardous materials such as mercury. Carefully open the base of CFL holder using an appropriate tool. You can see the electronic ballast circuit on a circular PCB.

Fig. 2: LEDs arrangement in waste CFL
Use the components from the ballast circuit and a series combination of four bright white LEDs as shown in Fig. 1. Remove all other components from the original ballast circuit. As per the requirement of light intensity in your room, you can increase the number of white LEDs up to eight.

As shown in Fig. 1, the full-wave bridge rectifier comprising diodes D1 through D4 converts AC voltage into DC voltage. Snubber capacitor C1 at the input reduces the line input voltage of 230V to a very low-level AC voltage. Series current-limiting resistor R2 and series inductor coil L1 avoid voltage spikes.

Fit the circular PCB in the waste CFL holder and your night lamp is ready for use.

Motion Sensor For Security Light by Abdul Rahman.

MOTION SENSOR FOR SECURITY LIGHT    

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Here is a system based on PIR motion detector module BS1600 (or BS1700) that can be used for security or corridor lighting in power-saving mode. The 12V DC power supply required for the motion detector and the relay driver is derived from 230V, 50Hz mains using a transformerless circuit.

The working of the circuit is simple. When you power-on the circuit after assembling all the components including the CFL, the CFL will glow for 10 seconds, turn off for 30 seconds, glow for 10 seconds and then turn off. Now the circuit is ready to work.

When any movement is detected, around 3.3V appears on the base of relay-driver transistor T1 and it conducts to energise relay RL1. As a result, Triac1 (BT136) fires to provide full 230V and light up the CFL. Another normally-opened contact of the relay (N/O2) is used here to hold the output until reset. If the switch is not in 'hold' position, the light will remain 'on' for about ten seconds (as programmed in the motion sensor). In short, when there is a movement near the sensor, the CFL glows for about ten seconds. It will remain 'on' if switch S1 is in 'hold' position.

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Use a three-pin connector for connecting the PIR sensor in the circuit with correct polarity. The motion detector is embedded onto the transparent cover of the light assembly.

 An arrangment of CFL assembly in the author's prototype (Fig. 3) is shown in Fig. 4. In this arrangement, a PIR sensor and 23W, 230V AC CFL are used. Seal all four sides with Blue Tac for water-tightness. Insulate the track side of the PCB using an insulating foam and glue to the base.  

Initiating our department activity..

Starting our department activity on today onwards.. Friends join our hands for some work..:)