ELF Monitor (CB21055E)

This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the 90s.

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Intermittent buzzer (CB20494E)
This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
Audio Oscillator (CB22250E)
This blocking oscillator was found in a publication from the 50's. The coils determine the...
20W amplifier per channel with the TPA3100D2 (Cb23591E)
The TPA3100D2 integrated circuit from Texas Instruments (www.ti.com) consists of an efficient...