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Laser torch-based burglar alarms normally work in darkness only. But this long-range photoelectric alarm can work reliably in daytime also to warn you against intruders in your big compounds, etc. The alarm comprises laser transmitter and receiver units, which are to be mounted on the opposite pillars of the entry gate. Whenever anyone enters to interrupt the transmitted laser beam falling on the receiver, the buzzer in the receiver circuit sounds an alarm. The range of this burglar alarm is around 30 metres, which means you can place the transmitter and the receiver up to 30 metres apart. Since the laser torch can transmit light up to a distance of 500 metres, this range can be increased by orienting the phototransistor sensor properly. To avoid false triggering by sunlight, mount the phototransistor sensor such that it doesn’t directly face sunlight. Long-range Burglar Alarm Using Laser Torch Fig. 1: Circuit of laser torch based transmitter The transmitter circuit is powered by 3V DC...

Description The use of transmitters which have a more powerful output than the ‘ flea-power ’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered device feasible. Whereas a typical micro transmitter will produce an RF power in the order of just a few milliwatts, i.e. a few thousandths of a watt, the VHF-FM transmitter described has a power output of between around a half and 2 watts, depending on the power source, which may be anywhere between 6 volts and 30 volts d.c. The battery or batteries should be of the alkaline high power type, since the current drain will be found to be relatively higher when compared to microtransmitter current drain. The power output of this device is somewhat proportional to the current drain and so therefore both may be decreased by altering the val...

Laser torch-based burglar alarms normally work in darkness only. But this long-range photoelectric alarm can work reliably in daytime also to warn you against intruders in your big compounds, etc. The alarm comprises laser transmitter and receiver units, which are to be mounted on the opposite pillars of the entry gate. Whenever anyone enters to interrupt the transmitted laser beam falling on the receiver, the buzzer in the receiver circuit sounds an alarm. The range of this burglar alarm is around 30 metres, which means you can place the transmitter and the receiver up to 30 metres apart. Since the laser torch can transmit light up to a distance of 500 metres, this range can be increased by orienting the phototransistor sensor properly. To avoid false triggering by sunlight, mount the phototransistor sensor such that it doesn’t directly face sunlight.  Long-range Burglar Alarm Using Laser Torch The transmitter circuit is powered by 3V DC. The astable multivibrator built around tim...

Laser torch-based burglar alarms normally work in darkness only. But this long-range photoelectric alarm can work reliably in daytime also to warn you against intruders in your big compounds, etc. The alarm comprises laser transmitter and receiver units, which are to be mounted on the opposite pillars of the entry gate. Whenever anyone enters to interrupt the transmitted laser beam falling on the receiver, the buzzer in the receiver circuit sounds an alarm. The range of this burglar alarm is around 30 metres, which means you can place the transmitter and the receiver up to 30 metres apart. Since the laser torch can transmit light up to a distance of 500 metres, this range can be increased by orienting the phototransistor sensor properly. To avoid false triggering by sunlight, mount the phototransistor sensor such that it doesn’t directly face sunlight. Long-range Burglar Alarm Using Laser Torch Fig. 1: Circuit of laser torch based transmitter The transmitter circuit is powered by 3V DC...

Nikon’s latest Coolpix cameras focus on durability and versatility, the waterproof, shockproof and freeze-proof AW120 leads the way  Nikon has announced seven new Coolpix cameras sporting a variety of features to complement different lifestyles from rough and rugged to slim and stylish. The Coolpix AW120 leads the pack with a 16-megapixel camera and is waterproof to 18m, shockproof to 2m and freeze-proof to -10°C for £329.99.  Meanwhile the 13-megapixel Coolpix S32 is an easy-to-use camera that’s shockproof, dustproof and waterproof for an active family lifestyle for just £99.99. The high performance entries on the lineup are the Coolpix P600 and super-zoom P530. Both cameras are compact with high zoom power and include a built-in electronic viewfinder that allows you to snap photos on the move. The Coolpix P600 will set you back £429.99 whilst the P530 costs £329.99. Nikon has also released the stylish Coolpix S9700 and S9600 cameras with built-in WiFi so you can upload and ...