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Of the received-frequencies' wavelengths in size (the ultimate Probe"-works fantastically for being such a tiny fraction The short whip antenna-more correctly called an "electrical-field J-FET, has an input impedance of about 10 megohms, which is why Is remarkably sensitive and works very well with short whip antennasīetween 1-3 metres in length, since it operates on the same principleĪs high-impedance "active antennas" designed for otherįrequency ranges (such as long, medium or shortwaves). receiver circuit ("BBB-4" standingįor a fourth version of my "Bare-Bones-Basic" designs) Possible using a small whip antenna while being highly immune to broadcast and utility station I also desired the BBB-4 to be as sensitive and low-noise as Was simple to build and use by newcomers to this realm of radio. Receiver schemes back in 1991, I opted to design a whistler receiver that This BBB-4 receiver can only be patchedĮither to an outboard speaker/headphone-amplifier or a microphone-levelĭissatisfied with more complicated and cumbersome multi-turn loop Like the WR-3/3E units nor a switchable audio-filter. The BBB-4 and WR-3/3E units are that the BBB-4 does not have a headphone amplifier Monitor audio frequency VLF Natural Radio. Its employment of a whip antenna to successfully and with sensitivity It is similar to the ready-made WR-3 I sell in Is also known as "Tandy" overseas, such as in the U.K. (such as the one available at Radio Shack ("Mini Audio Amplifier/Speaker"Ĭat. To a MICROPHONE-LEVEL input such as a tape-recorder or speaker-amplifier This receiver was designed to be hand-held or tripod mounted, and its output patched That occur as electromagnetic (radio) waves at audio-frequencies. With a passband peak at approximately 1.5 - 2 kHz, and is designed to The "BBB-4" is a broadband 0.2 to 12+ kHz V.L.F. 150 milliHenri choke(s) etc.īBB-4 receiver notes and other information: Q2: 2N3904 - a NPN bipolar transistor, radio shack cat # RSU 11328564Īudio transformer 8 ohm secondary, 1 K-ohm primary, center tapped, (Radioshack cat. 0047 uF (see notes above or below)ġ x 2.2 uF electrolytic (see notes below) Radio Shack sells the audio-transformer.Ĥ5)-ħ1)-Ģ x. C4 and C5 range from 0.0033 microFarads to 0.0047 microFarads regardlessĤ4b) of J-FET used.
VLF RECEIVER DIY SERIES
using one half of primaryĤ3) winding and the center-tap as a series inductor equalling approx.Ĥ4a) 160 milliHenry. for optimal gain)Ģ4)-Ģ5) AUDIO FILTER L1 (A PI-FILTER USING A COMMON AUDIO XFMR AS INDUCTOR)Ģ7)(From FET drain coupling cap C3) L1 (1KCT xfmr primary) OR 160-200 milliHenry chokeĢ8) = (Approx. Note this BBB-4v3 unit should employ "back to back zener-diode input protection - 2X 1N4733ATR (5.1v / 1 watt) zener-diodes optimal!Ġ3) \ | / _|_\ To Audioġ1) ant. I very much appreciate John's addition and his enthusiasm of the efficient BBB-4 VLF receiver - a project I first begun in late 1990 - it worked so well that it remains a basis for a good VLF receiver for audio-frequency natural radio phenomena listening in a simple, straightforward design! This addition should be of help to builders outside North America. For instance, 3.3 nf (nanofarads) equals 0.0033 uf (microfarads), and 4K7 equals 4.7K, 1K5 equals 1.5K. īelow is a schematic created by John Waghorn of the UK () with European parts designations. If you are interested in ULF reception (and great VLF coverage too), try this excellent and detailed website. Also, this unit will not receive ULF earthquake signals, nor am I very knowledgeable about such phenomena except for the very basics (I say this to reduce the number of inquiries I receive about such phenomena). If all instructions and notes are followed, there should be no problem with it whatsoever. Please see notes at the bottom of this sheet before contacting me about this unit.
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BBB-4 VLF Receiver forīroadband 0.1 to 15+ kHz reception of naturally-occurring ELF-VLF radio phenomena. at the drain output and this unit WILL receive Schumann resonance signals if in the open and away from AC sources by enough distance to reduce 50/60 Hz emissions to minimal/nil levels (or use DSP) - Earlier revisions: (October 2004 - jpeg schematic by John Waghorn in England added below) S. (R2)and the receiver will really shine! This is the WR-3 input also - also, swap the input protection diodes with 1N4733ATR diodes from ON semiconductor and the input will be extremely robust. with a 22uFĮlectrolytic (20v to 50v is fine) cap. REVISED RELEASE - May 2021: Use a 2N5486 N-channel JFET with 1K resistor (biasing R3 R4) on both drain and source leads. McGreevy BBB-4 Natural VLF Radio Receiver Plans Stephen P.