Electromagnetic field radiation detector having audible and visual indicators for detecting frequencies within the range of five hertz to four hundred kilohertz

Claim 1

A radiation detector adapted to detect and provide a warning of a presence of radiation having a frequency of about 5 hertz to about 400,000 hertz, said radiation detector comprising: coil means for sensing said radiation and for producing an alternating electrical current signal when said radiation is sensed; amplifier means, coupled to said coil means, for amplifying said alternating electrical current signal only when said frequency of the sensed radiation is less than about 2,000 hertz, thereby producing an amplified signal; first rectification means, coupled to said coil means, for rectifying said alternating electrical current signal only when said frequency of the sensed radiation is greater than about 2,000 hertz, thereby for producing a first direct current signal; second rectification means, coupled to said amplifier means, for rectifying said amplified signal, thereby producing a second direct current signal; summing means, coupled to said first and second rectification measure, for summing said first and second direct current signals, thereby producing a summed signal; comparator means, coupled to said summing means, for comparing said summed signal to predetermined value and for producing a comparison output signal only when said summed signal exceeds said predetermined value; first multi-vibrator means, coupled to said comparator means, for selectively producing a visual alarm signal only when said comparison output signal is produced by said comparator means; and second multi-vibrator means, coupled to said first multi-vibrator means, for selectively producing an audible alarm signal a predetermined time after said visual alarm signal is produced, thereby cooperating with said first multi-vibrator means to provide a warning of said presence of said radiation.