ELF direct conversion receiver test

ELF direct conversion receiver test. ELF receiver use earth spike antenna ( about 20...25m between spikes ).
Transmitter use 24V power source, transistor multivibrator and 24V relay.
Transmitter send direct current pulses in earth probe antenna, less than 1 Hz.
DX distace between RX and TX - about 40m.

[@xuliangmuzi1424]

Hello sir! Can you make a low-frequency (longwave) signal transceiver and use the receiver to receive the transmitter's signal for positioning, which we use for exploring caves, because cell phones and walkie-talkies (high frequency) can't penetrate rocks, while long-wave can

[@ingussilins6330]

In internet can find "Heyphone" cave radio communication circuit.
If use magnetic loop antennas, can find transmitters location in underground.
I think simple cave radio can made from VLF natural radio receiver and audio amplifier with mic and earth probe antenna ( transmitter ).

[@vanhetgoor]

Where can I find the schematics of a ELF receiver?

[@ingussilins6330]

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