RF & Radiation

Wireless Bug detector

This fairly simple circuit makes it possible to place such a wall as a conduit to locate. It is a conduit for power, no water or gas-seeker. The only requirement is that there is tension on the line. The antenna in the table can consist of a simple piece of copper wire. The correct adjustment is done through R7, in order to prevent the buzzer and LEDs still light up even though there is no leadership in the area. ..

FM Bug detector 80 - 150 MHz

This Mini FM Bug Detector is basically a broad-band receiver. It picks up the complete band from below 80Mhz to 150MHz and almost anything that transmits in that band will be detected. If a bug with a sensitive microphone is transmitting nearby, the result will be a feedback whistle. The Bug Detector will not determine the output power of a bug as it is detecting the sensitivity of the microphone. However it will prove the carrier section is working (this is the section that produces the 88MHz frequency) and also the audio section. ..

Negative Ions Detector / Sensor

Ions are defined as electrically charged atoms. Positively charged ions have a deficiency of electrons, and negatively charged ions have a surplus of electrons. An ion can also be classified as an atom or molecule with an electrostatic charge. Another classification of an ion is a charged particle that is formed when one or more electrons are taken from or added to a previously neutral atom or molecule. The Ion Detector described in this article can be used to detect the presence of free ions in the air. The Ion Detector, a handheld unit about the size of a pack of cigarettes, is designed to indicate ion emissions from Ion Generators, high-voltage leakage points, static-electricity sources, electric-field gradients, and in other situations where the presence of their relative flux density is required...

RF Bug detector

This circuit is not open for discussion. Although working perfectly, it was experimental. I will answer no emails in regards to this circuit. If you are looking for a more serious and reliable bug detector, go to the Countersurveillance Monitor article on the Circuits Page...

X-Rays with Receiving Tubes

Old TV tubes are used as cold cathode x-ray emitters in a simple apparatus developed by Bob Templeman of Chicago, Illinois. With selected beam power tubes of the type used in the high voltage section of TV receivers, the intensity is adequate to make x-rays photographs of objects using standard films. The earliest x-ray tubes were of the cold cathode variety. These tubes, referred to as Crookes or Hittorf tubes, were of the general class of gas tubes since the pressure had to be in the ‘soft’ vacuum range (about 10-3 to 10-4 Torr) to permit the passage of electrons from the cathode to the x-ray producing target in a so-called ‘dark’ discharge...

Simple RF field meter with LM358

This project will explain the function of a simple RF field meter. The unit will be in great help to tune transmitters for best performances. At the bottom left corner you will see a voltage divider. This divider is to produce a virtual ground of 4.5VDC. Above you will find the dipole antenna. The dipole antenna will pick up some radiated energy and the diode will rectify the RF signal to a DC voltage at VRF. This voltage is still quit low and needs to be amplified before it can control the panel meter. The signal then enter the OP which amplifies the voltage to suitable level set by the "Gain" potentiometers". The second OP acts as a voltage follower and set the offset (zero) for the panel meter. The panel meter is connected to the board via two wires (5meter long). To prevent any RF signal to be induced in this long wire I have added 2 ferrite block which will act as high impedance units. You can use any ferrite block or large inductor (10uH)...

Quadrature FM Detector

Quadrature FM detectors use a high-reactance capacitor (C2) to produce two signals with a 90 degree phase difference. The phase-shifted signal is then applied to an LC-tuned resonant at the carrier frequency (L1 and C3). Frequency changes will then produce an additional leading or lagging phase shift into the mixer. The diagram at right shows the impedance and the phase of a LC tuned circuit at 455kHz. As you can see, the phase (red curve) is 0 at the resonans. If the frequency is lower than 455kHz then phase angle is positive and if the frequency is higher than 455kHz the phase angle is negative. Conclution: If the frequency changes the phase will also vary and the output voltage (audio signal) to...

AVR LED RF Field Strength

Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere. It detects RF via a square law detector, basically its a crystal set with gain. The bias circuit for the detector is significantly modified from the probe to reduce the effects of battery voltage droop during use. The circuit contains a small analog section and LED driver, tied together by the micro controller. A two-transistor circuit provides a stabilized voltage and serves as a detector that serves an A-to-D converter based on the comparator contained in the micro controller. ..

Voltage Sensitive Probe

This circuit is so sensitive it will detect "mains hum." Simply move it across any wall and it will detect where the mains cable is located. It has a gain of about 200 x 200 x 200 = 6,000,000 and will also detect static electricity and the presence of your hand without any direct contact. You will be amazed what it detects! There is static electricity EVERYWHERE! The input of this circuit is classified as very high impedance...

No description available...

This project involves making several modification to an early 1960s era Victoreen CDV700 or CDV600-6B geiger counter. These counters are available on E-Bay for around $50 to $100. The modifications use modern electronic parts to improve the counter`s stability, extend the run time, and add a solar recharging capability...

This simple circuit produces a loud trilling noise, if no valid transmitter signal is received. This frequency must correspond with the resonant frequency of the piezo element, otherwise the sound level will be very low...

This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing LED. The device must be placed a few centimeters from the cellular phone, so its sensor coil L1 can detect the field emitted by the phone receiver during an incoming call...

This simple circuit is sure to have the police beating a path to your door - however, it has the added advantage of alerting you to their presence even before their footsteps fall on the doormat. The circuit transmits on Medium Wave (this is the small problem with the police). IC1a, together with a sensor (try a 20cm x 20cm sheet of tin foil) oscillates at just over 1MHz. This is modulated by an audio frequency (a continuous beep) produced by IC1b. When a hand or a foot approaches the sensor, the frequency of the transmitter (IC1a) drops appreciably...

The circuit of Figure 1 includes a PIN photodiode that detects individual photons of gamma radiation. The reverse bias on the photodiode sometimes creates a depletion region. When such a photon strikes this depletion region, a small amount of charge develops. This charge is proportional to the photon`s energy. Four amplifiers following the PIN photodiode amplify and filter the resulting signal. A final comparator distinguishes between the signal and the noise. Thus, the comparator`s output pulses high each time a gamma photon with sufficient energy strikes the photodiode...