Wednesday, 22 March 2017
Car Anti Theft Wireless Alarm
This FM radio-controlled anti-theft alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF, FM transmitter is fitted in the vehicle at night when it is parked in the car porch or car park. The receiver unit with CXA1019, a single IC-based FM radio module, which is freely available in the market at reasonable rate, is kept inside.
Receiver is tuned to the transmitter's frequency. When the transmitter is on and the signals are being received by FM radio receiver, no hissing noise is available at the output of receiver. Thus transistor T2 (BC548) does not conduct. This results in the relay driver transistor T3 getting its forward base bias via 10k resistor R5 and the relay gets energised.
When an intruder tries to drive the car and takes it a few metres away from the car porch, the radio link between the car (transmitter) and alarm (receiver) is broken. As a result FM radio module gene-rates hissing noise. Hissing AC signals are coupled to relay switching circuit via audio transformer. These AC signals are rectified and filtered by diode D1 and capacitor C8, and the resulting positive DC voltage provides a forward bias to transistor T2.
Thus transistor T2 conducts, and it pulls the base of relay driver transistor T3 to ground level. The relay thus gets de-activated and the alarm connected via N/C contacts of relay is switched on. If, by chance, the intruder finds out about the wireless alarm and disconnects the transmitter from battery, still remote alarm remains activated because in the absence of signal, the receiver continues to produce hissing noise at its output. So the burglar alarm is fool-proof and highly reliable. (Ed: You may have some problem catching the thief, though, if he decides to run away with your vehicle_in spite of the alarm!)
Copyright : EFY
Friday, 3 February 2017
Eye Fi x2 Wi Fi wireless memory cards
The Eye-Fi card is the 1st wireless memory card. It looks, stores media, and fits into cameras just like a regular SDHC card. On top of that, the Eye-Fi card has built-in Wi-Fi that uses your wireless network to effortlessly transfer photos and videos.
Upon setup, specify which networks the Eye-Fi card uses to transfer your media. Add up to 32 networks for your card to use. The next time your camera is on within range of a specified network, your photos and videos will fly to your computer and to your favorite sharing site.
gets media where you want it
During the quick set-up, you customize where you want your memories sent. The Eye-Fi card will only send them to the computer and to the sharing site you choose.
memory + Wi-Fi = Eye-Fi
It all started with a very simple idea: what if photos could just fly to where you want them to be? That’s how a memory card with antenna and magical superpowers was born.
More about Eye-Fi…
Wednesday, 28 December 2016
Wireless Mains Voltage Tester
Wireless Mains Voltage Tester Circuit diagram:
Notes:
- The circuit can be assembled on a Vero board.
- Use 9V PP3 battery for powering the circuit.
- Use a 10cm insulated wire as the sensor.
- The IC must be mounted on a holder.
- Switch S1 can be a miniature ON/OFF switch.
Monday, 26 December 2016
Genius Wireless Mouse without Battteries
According to Genius, all we need simply refill it for 3 minutes then the mouse can be used for a full day. With Genius Mouse DX-BlueEye ECO, it means we do not need extra money to purchase external battery pack and also preserve the environment. Genius Mouse DX-BlueEye ECO is using a frequency of 2.4 GHz and can be used within a maximum distance of 15 m and have a 800/1600 dpi. it will be sold with price of $ 39.99.
Friday, 9 September 2016
Complete Gsm based wireless electronic notice board circuit diagram
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