MOSFET VLF natural radio receiver circuit and circuit modifications.

This is a minimum part VLF natural radio receiver ( good for beginners ).
If use receiver, keep finger on (-) terminal ( grounding tought body ).
Circuit runs from single lithium ion battery or 3 x 1,5V batteries.

[@radiofun232]

Thanks for the many uploads (radio circuits) that you made on your YT Channel during the recent past. They are very good and interesting for everyone, also good that you show all the schematics so that people can make them + give an explanation. Much appreciated! 13 may 2023.

[@ingussilins6330]

Thanks! :)

[@jonathanlister5644]

Thanks so much, years ago I had a vlf receiver made by an american but lost it while camping

[@marcisberzins]

I am thinking about building natural radio receiver also. Something like your early schematics with some filtering.

[@ingussilins6330]

Vari droši izmantot visas shēmas, vai to variācijas. Būšu priecīgs redzēt tavu vlf dabasmātes rādio radiouztvērēju. :)

[@marcisberzins]

@@ingussilins6330 Paldies! Es pagājušajā ziemā vai rudenī pamēģināju uztvert Zviedru veclaicīgo radiostaciju SAQ 17,2 kHz ar internetā atrastu ieteikumu - pieslēdzu pie datora skaņaskartes līnijas ieejas (Rie=10 kOm) āra antenu - 30 m vadu. Pārveidot augsto frekvenci uz dzirdamu (600 Hz) bija domāta DL4YHF programma, kas satur gan spektra analizatoru, gan jaucēju un visu ko. Izņemot tādu kā vienu mirkli-zibsni (paralēli skatījos YT tiešraidi), uztvert SAQ neizdevās. Bet, runājot par 18,1 kHz krievu staciju - lūk tā gan bija saredzama gan analizatorā, gan pat telegrāfa signālus laikam sadzirdēju (protams, pēc jaucēja uz 600 Hz), tātad visai stipra.

[@arenaengineering8070]

👍🏻

[@user-io3yy9vp9n]

Zener diode has a very high capacitance, which has a shunting effect on RF input signals, and is therefore not a good solution for ESD protection. In your version of connecting a MOS transistor, between the drain and the gate, you can connect two parallel back-to-back diodes of type 1N4148 or similar, the total capacitance of which is negligible.

[@ingussilins6330]

This is a VLF receiver and works in audio freqencies 20Hz to 10kHz.
Receiver is a audio amplifier without any demodulator. With hight input impedance and low input capacitance. Any input protection device make capacitive voltage divider - antenna's capacitance and input capacitance - and reduce gain.
In this moment I use receiver without any input's protection.

[@user-io3yy9vp9n]

@@ingussilins6330 In any case, at near zero voltage, a zener diode can have a capacity of up to a thousand picofarads or more. While the 1N4148 has a capacity of only 4 picofarads. As I understand it, this is a receiver for recording atmospheric phenomena? What kind of antenna do you have? I think the most effective type of antenna for such a receiver would be an external antenna of the “up broom” type.

[@user-io3yy9vp9n]

@@ingussilins6330 I mean a "broom" antenna like the one in this image. In theory, its capacity should be very small. And with a receiver with a huge input impedance, it should have acceptable sensitivity in the frequency range you specified.
radiolamp.net/uploads/Image/beginners/sprav1938-7.png

[@ingussilins6330]

@@user-io3yy9vp9n Receiver for atmospheric phenomena "VLF natural radio". I use 1m long telescopic whip antenna or 1m long metal stick, or 1m long metering tape antenna.
Receiver can work with wet tree branch "antenna" - about 1m long.
Common GND (-) need connect to ground or use metal enclosure - grounded tought you body, fingers...

[@user-io3yy9vp9n]

@@ingussilins6330 But you won’t deny that a steel pin 30-50 centimeters long stuck into moist soil is much more effective than grounding using the “shoe-hand” method? In addition, this allows you to install the receiver motionless and free your hands.

[@andrewpetrenko2029]

Я думаю, этот приёмник можно использовать для поиска скрытой Эл. Проводки.

[@ingussilins6330]

Я использовал его с магнитной антенной (катушкой магнитного пускателя) и генератором звуковых сигналов для поиска кабелей и проводов. Надо будет снять видео на эту тему.

[@andrewpetrenko2029]

@@ingussilins6330 Да интересно бы посмотреть.

[@MAKSMIT-ME]

Предлогаю не мучаться с транзисторами , а использовать операционные усилители

[@ingussilins6330]

В 2008 году я уже пытался собрать ОНЧ-приемник с микросхемой операционного усилителя TL072 и активными RC-фильтрами (вся схема без транзисторах ). Схема работала, но не справилась с помехами от передатчика 18,1 кГц.

[@MAKSMIT-ME]

@@ingussilins6330 тогда хотя-бы ставить транзисторы типа MPSA62 , 63, 64.. малошумящие транзисторы для усиления слабых сигналов

[@MAKSMIT-ME]

@@ingussilins6330 но я все равно голосую за схему на операционном усилителе

[@ingussilins6330]

@@MAKSMIT-ME Конечно малошумящие транзисторы будут хороши, но в данном случае это не так важно. BS170; BC547; BC557 также очень хорошо захватывает и не имеет собственных шумов. Эту схему можно собрать на КП302...303; КТ315, КТ361, КТ3102, КТ3107 транзисторах.

[@andrewpetrenko2029]

Поэтому что ещё зелёный. Микросхема состоит тоже из транзисторов.