Hexamite

HE240S Sealed Ultrasonic Sensors

Main Index

For medium range applications and harsh environment.

  • Precision Positioning

  • Wind speed Monitoring

  • Doppler Applications

  • Echo Ranging 

  • Level Measurements (Solids and Liquids)

HE240STX. is an Ultrasonic Ceramic Transmitter, it can produce wide beam up to 120db output SPL (sound pressure level) at 40 kHz in air Single conductor shielded cable extends from the back of this sensor, for connection to a driver circuit.

HE240SRX is an Ultrasonic Ceramic Receiver, it can pick up 40Khz vibration or sound waves with, with sensitivity up to -58dB/V/microbar. Single conductor shielded cable extends from the back of this sensor.

The HE240S series sensor is protected by a heavy duty chromed brass housing, with 1/8" or 3mm thick walls. The American standard NPT configuration and 3/4" pipe size, readily available mounting accessories make this sensor easy to apply and install.

SENSOR APPLICATION EXAMPLES

HE240S Series

he240 transmitter receiver

Size: 1.05" dia x 1.60" -- 3/4" NPT

In the following, a HE240SRX receiver is placed opposite a HE240STX transmitter at a fixed distance. The transmitter referred to as T1 is exited with various voltage levels, and the opposite receiver referred to as T2 is used to receive the signal. The graphs below plot the output from T2.
 Above: T1 is exited with a 5Vp-p CMOS square wave oscillating at 40Khz, 100 waves are transmitted. The response as amplitude builds inside the T2 crystal is plotted above.
Above: 5Vpp CMOS/TTL square wave is applied to T1 at various frequencies. The frequency response is measured across the output wires of T2, and plotted above


Plot
Above: Continuous excitation voltage oscillating at 40Khz  is applied to T1. The T2 resulting amplitude is plotted.
plot
The above illustrates how the output of T2 decays as distance increases between T1 and T2. T1 is exited with oscillating voltage, amplitude 28V. 

 
plot
Above: T1 was excited with a 30Vp-p 40Khz step input at using signal conditioner HE40SCR, the illustration above shows how long it takes the system to settle on 40Khz. Distance between T1 and T2 is1.5m.
plot
Above: T1 excitation using HE40SCR 30Vp-p FSK (frequency shift keying) signal, low frequency 38647hz (duration 20 waves) and high frequency 40201hz (duration 26 waves). The response was monitored across output pins of T2, placed 1.5m apart from T1, and plotted as shown above. Note that the ripples are digitisation errors. 


Microchip PIC interface suggestions

The schematic below, shows how the PIC16C622 and the PIC16C71 can be interfaced to the HE2XX series transducers. For 40Khz transducers C1 an C2 should be about 2nF, R1 about 3Kohms and R2 about 5Kohms. R3 sets the level for the analog comparator of the PIC16C622 and should be high, say 50Kohm. If the A/D converter of the PIC16C71 is being used, R3 should be removed. 

schematic

ATMEL AVR interface suggestions

The schematic below, shows how the AT90S2313 microcontroller can be interfaced to the HE2XX series transducers. For 40Khz transducers C1 an C2 should be about 2nF, R1 about 3Kohms and R2 about 5Kohms. R3 sets the level for the internal analog comparator of the AT90S2313 and should be high, say 50Kohm.

schematic


INTEL 8051 interface suggestions

The schematic on the right, shows how the INTEL 8051 microcontroller can be interfaced to the HE2XX series transducers. For 40Khz transducers C1 an C2 should be about 2nF, R1 about 3Kohms and R2 about 5Kohms. R3 sets the level for the analog comparator and should be high, say 50Kohm.

 

schematic

Cable length between the HE240 series transducers and a signal conditioner, is left to the user's discretion. At 10m lengths the added environmental noise and signal reduction at 40khz is insignificant.

Beam Pattern

The sensor is located in the locus of the polar plot shown below facing north, maximum signal strength is along the 0 degree axis. As the observer with the measuring instruments moves east and west i.e. perpendicular to the 0 line signal strength degrades. The beam pattern character line shown below represents observation angles where signal has degraded by 6 decibels.

 

Electrical Specifications HE240STX

Parameters Values Units
Operating Frequency 40 kHz
Input Voltage 20 (max) Volts (RMS)
Output (SPL) 120 db
Input Impedance 300 ohm
Beam Spread 12 degrees
Bandwidth 1 kHz
Temperature -40 to 100 C


Electrical Specifications HE240SRX

Parameters Values Units
Operating Frequency 40 kHz
Receive (Sensitivity) -58 dB/V/Ubar
Output Impedance 300 ohm
Reception Angle 12 degrees
Bandwidth 1 kHz
Temperature -40 to 100 C

Housing HE2XX Series

Housing Description Units
Material Type Brass  
Protection NEMA 12 (IP68)  
Diameter 1.05 In
Diameter 27  mm
Length 1.6 In
Length 41 mm
Leads Length (attached) 0.3 meters
Panel Nut Threads 3/4" - 20

NPT