We found this antenna amplifier or Booster circuit in an Electronics Now from the 90s. The circuit can be implemented with equivalent transistors like the BF494.
This circuit can also operate with SW and even VHF signals up to 150 MHz. The circuit can be...
This integrating circuit multiplies the time that can be obtained with a 555 timer. We find it in...
This transmitter for the 7 MHz range, as we can assume by the number of turns of the coil, since the...