Radio Frequency
Wireless headphones receiver circuit schematic
The wireless headphones receiver presented is an standard application of ZN415 produced by Ferranti ( short wave receiver ). ZN415 assures a quality reproduction, has a 1.5 battery alimentation and contains a MA detector and audio amplifier.
The current consumption is < 5mA, L1 has 40 turns, 0.2 Ø copper and 20mm Ø ferrite. C1 is [...]
Radio field indicator with MOS-FET
A rf field indicator is required to verify power stages and transmitters antennas. With this radio field indicator you can measure radiated energy from antenna. This circuit is very sensitive, a weak signal is enough.
The S2 commutator allows to select : 480KHz … 2.4MHz / 2.4MHz … 12MHz / 12MHz … 40MHz.
A 30cm long wire [...]
Radio field signal strength indicator
A radio field signal strength indicator is very usefull for determine radiation patterns of transmitters antennas. An ancillary antenna must be put close to main transmitter antenna. The received signal is applied to L1,L2 and C2, this allows the field indicator circuit to adjust to the same frequecy as the transmitter. With the coils values [...]
