Aligning the transmitter with chip camcorder, it is easy to get set up for wireless video surveillance, and for efficient operation of batteries, it is recommended to combine this device with an infrared detector presence, a commercially available many foreign firms worthwhile and relatively inexpensive, for example detector "REFLEX" company "TEXECOM" is able to capture the outside interference, resistant to false alarms, electromagnetic and radio frequency radiation.
Adding to the scheme of video transmitter high-frequency amplifier, made on the same transistor type CT, you can increase the power output of the transmitter, and correspondingly the range of wireless communication with the television tuner.
Schematic diagram of the transmitter contains one transistor VT 1 type CT 603, the Transmitter tuned to the frequency of one of the free TV broadcast channels (e.g., 1....5 channel). Adjustment is carried out by means of trimmer capacitor 4, which achieve the capture of the baseband signal. Fine tuning of the transmitter is produced by resistor R1. The signal from videoprobe is input to the transmitter in the emitter circuit of the transistor through a resistor R6 and capacitor C9.
Modulated by the video signal from the collector is fed to a resonant circuit L1 C4 in the antenna. The current at point a is chosen in the range 30....35 mA.
Correctly assembled the transmitter works immediately. In the absence of the generation you need to check the voltage at the emitter of the transistor VT1, and the voltage across it must be different from the voltage on the base 1...2 in a big way.
The transmitter should be powered from a stabilized power supply. The antenna must be of rigid construction, such as the type telescopic.
Instead of the transistor QT you can use CTB or another, with appropriate parameters.
The transmitter preferably be placed in the screen to reduce interference.
Publication: N. Bolshakov, rf.atnn.ru