Circuit Wiring Solution

This FM radio-controlled anti- annexation anxiety can be acclimated with any agent accepting 6- to 12-volt DC accumulation system. The mini VHF, FM transmitter is adapted in the agent at night back it is anchored in the car balustrade or car park. The receiver assemblage with CXA1019, a distinct IC-based FM radio module, which is advisedly accessible in the bazaar at reasonable rate, is kept inside. Receiver is acquainted to the transmitters frequency. Back the transmitter is on and the signals are actuality accustomed by FM radio receiver, no hissing babble is accessible at the achievement of receiver. Appropriately transistor T2 (BC548) does not conduct. This after-effects in the broadcast disciplinarian transistor T3 accepting its advanced abject bent via 10k resistor R5 and the broadcast gets energised.

Back an burglar tries to drive the car and takes it a few metres abroad from the car porch, the radio articulation amid the car (transmitter) and anxiety (receiver) is broken. As a aftereffect FM radio bore gene-rates hissing noise. Hissing AC signals are accompanying to broadcast switching circ- uit via audio transformer. These AC signals are rectified and filtered by diode D1 and capacitor C8, and the consistent absolute DC voltage provides a advanced bent to transistor T2. Appropriately transistor T2 conducts, and it pulls the abject of broadcast disciplinarian transistor T3 to arena level.

The broadcast appropriately gets de-activated and the anxiety affiliated via N/C contacts of broadcast is switched on. If, by chance, the burglar finds out about the wireless anxiety and disconnects the transmitter from battery, still alien anxiety charcoal activated because in the absence of signal, the receiver continues to aftermath hissing babble at its output. So the burglar anxiety is fool-proof and awful reliable.

Overview

This digital thermometer project uses any standard FM broadcast band radio at regular intervals in order to report the temperature.

Explanation

An Atmel AT90S1200 is used to construct the prototype along with a modified low cost wireless microphone kit that function as the transmitter in order to save design time. The device can be used as standalone or as part of a PC-based weather station or HVAC system since it uses a simple low bit rate tone signaling scheme which can be interpreted easily by both machines and humans. The design allows the use of any inexpensive FM radio to monitor the temperature with easy set up of any number of monitoring locations.

There are various circuits used in this project including, the thermometer interface, audio interface, and power interface. The operation consists of applying power and tuning the unit to any unused FM channel. A 9V transistor radio battery was chosen since the 5V regulator used can accept any DC voltage between 5.5V-12V. A programs tests if larger or lesser and converts the binary format temperature output from the thermometer clip to a format that can be transmitted a digit at a time.