dc tachometer generators
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DC Tachometer Generator Catalog Download pdf
NEW - ST-7565 Series Low Cost - Easy Mount DC Tachometer Generator

Servo-Tek DC Tach Generators have been an industry standard for over fifty years.

Servo-Tek Tach Generators provide a convenient means of converting rotational speed into an isolated analog voltage signal suitable for remote indication and control applications. While the following pages contain information on our most popular Tachometer models, we also manufacture countless special dc Tachometer Generators for specific applications.
The data presented here is true of all DC Tachometer Generators outlined in this catalog.

Applications - DC Tach Generators

Servo Systems

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 relationships with minimum ripple. DC Tachometer Generators are also excellent rate generators for velocity damping in position servos.Servo Motor DC Tachometer Generator .250" dia shaft 3volts/1000rpm

Speed Transducers/DC Tach Generator

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.

Technical Data

Tach Generator Construction

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.

Brush Life/DC Tachometers

Tachometer Generator brushes and commutators are matched for long life and stability. Operation at 1 mA output will deliver maximum brush life.

Linearity/DC Tachometers

Linearity, of Servo-Tek DC Tach Generators, at any speed is better than 0.1% of the output at that rpm.

Ripple/DC Tachometer

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/DC Tachometers

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/DC Tachometers

Optimum brush and commutator combination gives 0.1% stability. Highly stable output gives no evidence of long-term drift.

Breakdown Voltage/DC Tachometers

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. Series E-500 volts.)

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, with the exception of Series D and E.

Six armature winding specifications.

Servo-Tek DC Tach Generators are grouped in six Series, each identified by a single letter immediately following the digit string in the middle of the model number. This Series designator identifies armature length and characteristics. The groupings break down this way:

A-series dc tachometer up to 10volts/1000 rpm

B-series dc tachometer up to 24 volts/1000 rpm

D-series dc tachometer up to 50 volts/1000 rpm

E-subminiature tach generator 3 volts/1000 rpm

F-series dc tachometer generator -low ripple output voltage up to 10 volts/1000rpm

H-series dc tach generator -low ripple output up to 16 volts /1000 rpm
ST-7565 Series Low Cost Easy Mount DC Tach Generator
Also available: Tachometers with Sealed Shafts  Ruggedized Tachs
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As the dimensions of the armature (with commutator) change, so do the outline dimensions of the permanent magnet and the housing that encloses it. The larger the desired output voltage, the longer the armature winding. When the existing space is exhausted, the armature is made longer to increase voltage output (e.g. moving from armature A to B). Note that the Series designator refers to the Tach output voltage, not to the housing length. The housing length will change with the level of ruggedization or other special construction requirements of a given housing application.
Standard Tach housings, except for the E series (subminiature), are 1.135" in diameter. Ruggedized Tach housings have larger diameters, as required by the application.
Go to "Using DC Tachometer Generators-the simple velocity feedback solution" for more information

Tachometer Generator Catalog Download pdf