DC Tachometers

Servo-Tek tachometer generators (also caleed tach generators) provide a convenient means of converting rotational speed into an isolated analog voltage signal suitable for remote indication and control applications.

Combining high accuracy with low driving torque, Servo-Tek tach generators are ideal for use in servo systems.  

Tach Generators are particularly suited to application in precision integrators and velocity servos, both of which require a highly linear speed/voltage relationship with minimum ripple.  

DC Tachometer Generators are also excellent rate generators for velocity damping in position servos. The nearly pure dc output-with no phase shift-allows Servo-Tek Tach Generators to be used as feedback transducers for numerous types of equipment, including fast-response servos and other devices. 

Servo-Tek Tach Generators are housed in aluminum casings protected in accordance with Mil-C-5541 or Mil-A-8625. Alnico permanent magnets are used.  Armature shafts are stainless steel, and rotate on fully-shielded stainless steel ball bearings.  Commutators are made from an alloy containing 95% silver. Armature laminations are wound with Isomid insulated wire, over Teflon slot insulation.  The entire armature is impregnated and baked, resulting in a NEMA Class H insulation system.


Servo-Tek Tachometer Features

  • Brush Life: Tachometer Generator brushes and commutators are matched for long life and stability.  Operation at 1 mA output will deliver maximum brush life.
  • Linearity: Linearity, of Servo-Tek DC Tach Generators, at any speed is better than 0.1% of the output at that rpm.
  • Ripple: The DC Tachometer Generator ripple rms value will not exceed 3% of the dc value at any speed in excess of 40 rpm on standard units; 1.5% on low-ripple models.
  • Bidirectional Operation: All Servo-Tek DC Tach Generators operate in either rotational direction.  That direction can be determined by output voltage polarity. Output (in either direction) is held to a tolerance of 0.25% of the average output.
  • Stability: Optimum brush and commutator combination gives 0.1% stability.  Highly stable output gives no evidence of long-term drift.
  • Breakdown Voltage: Servo-Tek DC Tach Generators are factory tested with an ac potential of 1,250 volts rms applied for one second between (either) terminal and the shaft.
  • Temperature Range: Tachometer Generators are designed for continuous operation in ambient temperatures ranging from -55°C to +100°C(-67°F to +212°F).  Voltage output at 25°C will not deviate by more than 0.01% per degree of change within the range of -20°C to +75°C.  All Tachs are temperature compensated, except for Series D and E.

Servo-Tek Series Datasheets

  •  A Series - DC Tachometers with output signal between 1 and 10 volts/1000 rpm.
  • B Series - DC Tachometers with output signal between 11 and 24 volts/1000 rpm.
  • D Series - DC Tachometers with output signal between 25 and 50 volts/1000 rpm.
  • E Series - DC Tachometers with output signal between 0.7 and 3 volts/1000 rpm.
  • F Series – Low ripple DC tachometers with output signal between 1 and 8 volts/1000 rpm.
  • H Series - Low ripple DC tachometers with output signal between 5 and 16 volts/1000 rpm.
  • J Series - Low ripple DC tachometers with output signal between 16 and 30 volts/1000 rpm.
  • Sealed Tachometers available with a variety of outputs.

View Specification Tables for More Information

A&B Series Tachs

D&E Series Tachs

F H & J Series Tachs

Sealed Tachs