Found in a 1990s American technical brochure, this circuit is intended for alarms that use as photodiode sensors. The circuit has a frequency response of up to 20 kHz. The gain is 40 dB.
This circuit uses a 555 (according to the diagram) to generate 50 ms tone bursts at a frequency of 1.5...
This circuit is intended for SSB transmission by generating two sideband signals with the carrier...
XTAL from 4 to 20 MHz can be used in this oscillator. The XRF choke can range from 10 to 100 µH...