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ULF/ELF/VLF receiver and antenna (2007.10.09:2 tech_notes2#20 maxwell_notes#9)



receiving ELF waves in a frequency range between zero and approximately 25 Hz

various VLF receivers/EM sniffers:

Coil for VLF receiver: (2007.10.08:1 maxwell_notes#8 tech_notes2#17)

For the following: http://www.vlf.it/kurt/elf.html

40cm diameter. 1000 winds of 0.6mmm wire

AD8313-based board for Maxwell: (2007.05.24:1)

Generates audio signal on output (from RSSI / 100 MHz to 2.4 GHz)

Design and board from:


with variable resistor replaced with 1K

see also: http://www.analog.com/en/prod/0,,770_847_AD8313,00.html


for antenna:


Maxwell workshop prototypes. (2007.05.18:1)

With brief explanation. Working clockwise from top left:

1] Broadband/all-band receiver. After: http://www.techlib.com/electronics/allband.htm

Using BAR28 small signal Schottky diode as detector.

2] Broadband receiver with frequency divider. Based on the LM386 audio amp and the 4020 ripple counter - jumpers for output with frequency divided by pins 4,6,9,12,14 as by 16,64,512,4096 and 16384 respectively.

3] Radar/microwave detector. After: http://www.electronics-lab.com/projects/misc/004/index.html

4] EM/ghost detector (can be used with coil or with photodiode (as sound to light)) after Newton C. Braga Electronic projects...

5] Sound to light using LM386 and selected photodiodes (long lead/anode to + symbol).

6] All-band receiver with 50 Hz notch filter (Q or width adjusted with poti). Jumpers for other input.

Maxwell [JOVE RJ1.1 radio telescope receiver kit] (2007.05.03:2)

1] Component assembly:

4024 as frequency divider - for Maxwell: (2007.04.26:3)

using 4024 7-stage binary counter as a frequency divider in series with LM386 to amplify EM (from a coil or antenna). After:


(note we can also add cap/resistor on second of the LM386s)

We can tap audio from pins 3,4,5,6,9,11,12 at various frequencies:

Maxwell experiments: (2007.04.23:3)


1) Non-functioning Geiger counter from two circuits:





2) Radar/microwave detector:


3) Wideband/broadband receiver:


for Maxwell City workshop: (2007.04.17:1)

Light to sound circuit using SFH300-3 (>0,063mA/35V/420-1130nm) photodiode, TL082 op-amp and LM386 audio amp ICs:


Maxwell City workshops: notes, research, experiments (2007.04.11:1)

(for workshops in Oslo, May 2007: http://anart.no/projects/maxwell-city/

and open call:

http://anart.no/2007/03/14/maxwell-city-call-for-workshop-participation/ )

1] Notes:

Rough conceptual notes to be expanded:

City as circuit (diagram). body as active within this circuit

VLF scene - intentionality in transmission/reception - deciphering of a (military) signal, a ghost signal

City as doubled (above and below also - above and below of AC)

Geography of magnetic fields (vertical, horizontal)

Neither reception nor transmission but interference and resonance - a new articulation of relation of objects and space - of the active. eg. effects of antenna, wire interventions, capacitance, induction, field effects

Questioning of a "making visible/audible" - transparency of intervention, of being in city

Operation at a distance - poltergeist effects

Use of (primarily) metal structures evident in the city to record effects - at the same time deployment of large components or construction of components and a kind of circuit diagram using base materials and city structure.

also to make use of doubling and frequency notes from makeart_notes

2] Experiments:

0] misc circuits that could be useful:

small audio amplifiers, op-amp-based pre-amps (see below), notch filters for 50Hz

1] beacons


[self constructed beacon using a cheap 40106 Schmitt trigger and two transistor (FET) astabile transmitter:


is used for antenna experiments below.

see also the RC-Generator using one Schmitt trigger to dominate one part of HF radio spectrum:


TESTED: using 40106 Schmitt trigger chip and 3.5pF-22pF Trimmerkondensator it hardly dominates with antenna very close to cheap FM radio around 98 MHz - note that can use another trigger on chip with poti and cap and feed the square wave to modulate our high frequency. perhaps nice as breadboarded demo...

also can be amplified using 4069 invertor (diode and resistor across pins 1 and 2 (one invertor) - quite successful across several harmonics on narrow stock FM radio spectrum - also works well using VLF probe


2] resonant objects in the city - use VLF receiver and make PCBs for this

3] WiFi and signal strength using AD8313 or similar

4] AnteNna experiments using various materials and diode as detector for dominant signal to be amplified - these are not tuned to a certain frequency:

[signal is from mini-FM transmitter as self-distributed kit from superfactory people: http://kulturserver-berlin.de/home/piradio/funkleh2.htm#Kippstufe ]

5] geiger counter

6] microwave detector

7] ion chamber

8] IR and photo-transistors/diode - light (frequency of modulations) to sound circuit

using simple circuit with TL082 op-amp (both amps used with input into + and 1M resistor across output and -) and with 100uF across 1 and 8 of LM386 audio amp - op-amp and LM386 is useful combination for signals amplification

LM386 - 3 and 4 to GND, 2 as input. by way of 100uF electro to small speaker

(more or less as forest mims)

reverse bias the photodiode (cathode to 100K to +9v)

9] electroscope

10] pyroelectric sensor:

using LHI968 and application notes