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OVERVIEW

  Extended Low Frequency (E.L.F.) Accelerometers

Unique ELF technology combines the most desirable features of piezoelectric sensors (excellent high frequency response) with those of variable capacitance MEMS accelerometers (true DC response) to create the widest possible bandwidth, from DC (0 Hz) to 10 kHz.


Dytran has developed a new generation of vibration instruments that combines two technologies, which until now, have never been used simultaneously. Also referred to as the E.L.F. (Extended Low Frequency), instruments contain a piezoelectric and a variable capacitance element with respective filtering whose outputs are electrically superimposed over one another.

The Dytran 7705A series features a hybrid design, combining the most desirable features of piezoelectric sensors and variable capacitance accelerometers, which result in a flat frequency response from 0 to 10,000 Hz.

ELF accelerometers are ideal for the following applications:

  • Flight and flutter testing
  • Health & Usage Monitoring Systems (HUMS)
  • Machinery monitoring
  • Ride quality
  • Wind turbine measurements
  • Wide range of structural response applications


The main principle of operation of the Dytran 7705A series is the instrumentation amplifier at the output buffer. The positive input is provided by the variable capacitance element and the negative input is provided by the piezoelectric element. Both the variable capacitance element and the piezoelectric element are filtered appropriately (low pass single pole and high pass single pole, respectively) to provide the corner frequency of both filters precisely matched at approximately 30 Hz. Both signals are also out of phase as they enter the instrumentation buffer. Accelerometers are powered through the power pin with a 5-28 VDC power. Each accelerometer requires 7-9 mA of current.

Designed in a hermetically sealed, titanium housing, the 7705A series incorporates a 10-32 tapped hole and radial 4-pin M4.5 x 0.35 radial connector. Units are available with ranges of 20g, 40g and 200g.

Supplied Accessories: (1) model 6200 mounting stud

Recommended Accessories: model 6213 adhesive mounting base, model 6258 magnetic mounting base

Compatible Cables: 6776A