Among the Amateur Radio fraternity, a device such as the one described here would otherwise be known as a Field Strength Meter (FSM). Its main purpose would be to check that RF power is being radiated from a transmitting antenna. Some FSMs are tuneable across a wide range of frequencies, which allows the device to work with different transmitters and antennae - usually from HF to VHF and beyond. A difference with this unit is that it is only sensitive to those signals in the R/C section of the radio spectrum. The on-board trimmer allows you to tweak for maximum signal strength of your frequency of choice, whether it be 27MHz AM, or 40MHz FM.
In order to read the received signal strength, such a unit would ordinarily employ a mechanical analogue meter. The unit described here differs in that it uses four super-bright LEDs. The benefit of this is that it allows you to read the display from a distance - even in bright sunlight.
Download schematic(gif), PCB1, PCB2
Electronic Circuit Project, FM tranmitter, Field Strength Meter, Analog circuit (src)
Sunday, November 8, 2009
This project suitable for people who like with the transmitter system. It's an electronic analog project. You don't have to programming the IC to build it. The function of this electronic project is to measure the RF power being radiated from a transmitting antenna.