Simple DIY Cell Phone Radiation Detector

This easy to build microwave radiation detector circuit consist of a high brightness LED and nine germanium or 1SS86 detector diodes. They need to be connected correctly.  All these components are ready to assemble, simply solder the germanium diodes and LED into a simple microwave radiation testing circuit as shown in the diagram.


On a new LED the long lead is the positive (anode) while the short lead is the negative (cathode). The germanium diode has a line (band) around the end which is the cathode. When correctly wired the LED and the germanium diodes are connected so they both allow current to pass in the same direction, i.e. in the circuit diagram the arrows point in the same direction. In practice this means the LED and germanium diode are joined at the cathode of one and the anode of the other.

How it works and how to use it

When a radio wave passes across a metal object the EM fields cause the charged electrons in the metal to oscillate and this causes small AC currents at the same frequency to be induced into the metal.

When placing a call or texting, the radio waves emitted from the phone pass across the RF detector diode loop and this induces a voltage into the diode loop–   if it is close enough —  current will light the LED and warn you of potentially dangerous microwave radiation.

A Smartphone automatically tests the network and adjusts its transmission power to maximize battery life and minimize network interference. As a result the brightness of the LED meter will depend on the data being sent (the average signal), the local signal strength and how close the diode loop is to the cell phone.

The detector diode is made up of a tiny wire which only makes a point-of-contact onto a piece of semiconducting germanium so it’s ‘self’ capacitance is very low and keeps current in the diode loop flowing in one direction.

The germanium diode will rectify the AC signal from the diode loop forming a series of DC pulses that will be nicely smoothed by the LED’s capacitance.  Without the diodes however the raw AC signal from the conductive loop will tend to be averaged to zero by the LED’s capacitance.

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