This unit covers the 35 to 45 kHz ultrasound band.
The RX3 ultrasound receiver kit replaces the RX2. It features lower-noise, higher gain, and center-frequency adjustment for the detection of weak coherent and/or noise-based signals in the 32 to 42 kHz range. These changes - to accommodate location of RF noise due to lower level power line sparking - were substantial requiring a completely new PCB.
Stand alone, the unit is ideal for listening to bats and insects, detecting air leaks, or finding other ultrasound sources. Combined with our 12-inch parabolic dish (sold separately) it is useful for pinpointing signals at 20 to 50 feet and includes an adjustable center frequency for focusing on frequency-specific targets.
The Kit is shown in the picture. The PCB (5.68 by 3.16 inches) fits snugly in its clam-shell case (L 6.16 W 3.677 H 1.378 inches), along with two 9V batteries and a 400SR016 piezo transducer (PZT). The circuitry expands on that of the RX1 and Rx2, featuring a low-noise, high-gain 40 kHz amplifier, a 602-style mixer, two-stage low-pass filter, and audio preamplifier. Two outputs are provided, a mono-output of the preamplifier signal and a boosted output for 8 - 24 ohm headphones or a small speaker. Kit time for the experienced builder is less than two hours. Through-hole parts are used throughout. The 9-volt batteries and parabolic dish are not included.
The signal pressure levels of natural and man-made ultrasound emissions can vary widely. Transmissions by bats can be strong at close range but will be weak at a hundred feet. Pressure signals caused by sparking on AC power distribution systems are generally weaker and copy must be assisted by the addition of a gain antenna, such as our 12-inch parabolic dish sold separately. A typical weak spark, generated at 400 volts on an AC power distribution system, may produce a weak RMS pressure of 0.5 Pa to 2 Pa (75 micro-psi) at ten feet.