Nidec Copal REC16K / REC16L / REC16M Incremental Rotary Encoder

The Rotary Encoder series includes optical and magnetic encoders. Optical models run from φ 12 to φ 30 and include small, light weight, and low cost models, as well as high resolution, and manual setting models.


The Rotary Encoder series includes optical and magnetic encoders. Optical models run from φ 12 to φ 30 and include small, light weight, and low cost models, as well as high resolution, and manual setting models. These encoders can be used to sense the angle, size and rotation speed of industrial equipment, including industrial robots, numerically controlled (NC) machine tools, elevators, production equipment, terminals at financial institutions, computer peripheral equipment, etc. They can also be used as manual setting encoders for digital equipment, such as measuring, communications and medical equipment.


Optical encoders

The light from the LED which passes through the slit of the rotating disk actuates the photo-sensor. The output of the photo-sensor which is quasi-sinusoidal is shaped into square wave by the voltage comparator and fed into a logic circuit.

Magnetic encoders

Principle structure is composed of magnetic sensor and magnetic drum (corresponding to LED and photo-sensor in an optical encoder). Without power consuming LED, total dissipation power of the magnetic encoder is far less than that optical encode

Magnetic encoders
Magnetic encoders


Quasi-sinusoidal signal output (RE20F)

Output signals of the RE20F rotary encoders are direct signals from the photo-sensor in the quasi-sinusoidal wave form. An external circuit is therefore required to shape them into square wave signals. Fig. 3 shows the output amplitude variation (ripple), ΔEs which is defined as follows.

Square wave signal output

(REC16, RES16, RES20D, REC20D, RESW20D, RECW20D, RMS20, REC20, RES20B, REC20C, RE12D, RE30E)

Output signals of the series encoders are in the form of square waves and can be fed into a digital circuit directly
without an interface. There are three versions available, for 5 V output, 12 V output and 24 V output.


Output “Z” : This is an index output of one pulse per turn and is used as a reset signal or start signal. The encoders are so designed that there will be only one rising edge on CW rotation (falling edge on CCW rotation) in the output “B” during the time period when the output “Z” is “high”. Therefore, an ideal reference position signal can be obtained by getting the outputs “B” and “Z”.
Output “A” : This is a basic output and will give as many pulses per turn as the resolutinon.
Output “B” : This output is the same as the output “A” except that there is an electrical phase difference of 90° between the output “A” and “B” and is used to sense the direction of rotation.

The rotating direction is usually determined by sensing the signal level of the output “B” at the pulse edge of the output “A”.


The maximum operating speed of the encoders is given by the following formula.
Maximum speed (min-1) = Maximum frequency response (Hz) × 60/ Resolution (P/R)
Note) Encoders exceeding the above limit may be available on a special order basis.


Nidec Copal

Nidec Copal

NIDEC COPAL ELECTRONICS was established in April 1967 in Japan as a specialty manufacturer of electronics components. The company's philosophy remains unchanged - to be a supplier of high quality products while offering competitive prices. NIDEC COPAL ELECTRONICS began by developing a wirewound trimmer. This product was enthusiastically received by many sectors in the industry. The initial success of the trimmers laid the groundwork for future development of a wide selection of manufactured products that combined electronics at the start of the electronics revolution.

Later, robust sales of cermet trimmers led to the company's remarkable expansion. Further development efforts led to the release of a succession of new product lines. These included a wide range of motors, encoders, switches and pressure sensors.


  • Outstanding operation feeling
  • 16mm square compact size
  • Excellent click & switch feelings
  • Long life of 2 million cycles


  • Input equipment for lmage simulation, e.g. CAD
  • Cursol position setting for wave observation of Oscilloscope etc.
  • Level settings for ultrasound imaging devices
  • For manual setting of broadcasting system, e.g. switcher


Electrical characteristics

Input voltage DC5 ± 5 %
Input current 30 mA maximum
Output wave form Square wave
Output phases A, B
Resolution(P/R) 25
Phase difference of outputs A & B 90° ± 45°
Maximum frequency response 100 Hz
Output signal “1 (High)” + 4.5 V minimum
“0 (Low)” + 0.5 V maximum
Light source LED

Switch characteristics

Maximum contact rating DC15 V, 20 mA
Contact resistance 2 Ω maximum(Initial value)

Note) Manual setting only.

Mechanical characteristics

Click torque 7.35 mN·m ± 2.5 maximum(75 ± 25 gf·cm)
〈REC:With click〉
Click number 25
Shaft loading (Pull-push) 19.6 N maximum (2 kgf)
Switch operation force 2.45 ± 1.47 N (250 ± 150 gf)
Switch stroke 0.3 ± 0.2 mm
Rotational life (Mechanical) 2 million cycles
Switching life 1 million cycles
Shaft loading
(When mounting)
Radial 4.90 N maximum (500 gf)
Axial 2.94 N maximum (300 gf)
Net weight Approx. 12 g
Strength of tighten screw 1 N·m {10.2 kgf·cm} maximum

Environmental characteristics

Operating temp. range 0 ~ 50 °C
Storage temp. range – 20 ~ 80 °C
Protection grade IP40


Part Number Designation

REC16 K 25- 2 0 1
Series name Push switch function and shaft

01: 1 bit     03: 3 bits
02: 2 bits   04: 4 bits
08: 8 bits




2:“A” & “B”

  Output interface

5:Open collector

List of Part Numbers

Part number Output interface Shaft Push switch function Click Resolution
REC16M25-201 Voltage (PIN HEADER Type) Single Shaft No With Click 25 (P/R)
REC16K25-201 Voltage(PIN HEADER Type) Single Shaft Yes With Click 25 (P/R)
★REC16K25-205-B Open Collector (SCOKET Type) Single Shaft Yes With Click 25 (P/R)
★REC16L25-205-B Open Collector(SCOKET Type) Double Shaft Yes With Click 25 (P/R)

The products indicated by ★mark are manufactured upon receipt of order basis.

Realibility Test

  • The output shall satisfy the criteria below after the following tests.
Test item Test conditions
Vibration Power OFF Amplitude : 1.52 mm or 98.1 m/s2 (10 G) whichever is smaller.
10 ~ 500 Hz excursion 15 min/cycle, 8 cycles each for X, Z, directions.
Shock Power OFF 3 times each in directions (X, Z) at 490 m/s2 (50 G), 11 ms.
High temperature
Power OFF 80 °C 96 h (To be measured after leaving samples for 1 h at normal temperature and
humidity after the test.)
Power ON 50 °C 96 h
Low temperature
Power OFF − 20 °C 96 h
Power ON 0 °C 96 h
Humidity Power OFF 40 °C  Relative humidity 90 ~ 95 % 96 h
(To be measured after wiping out moisture and leaving samples for 1 h at normal temperature and humidity after the test.)
Thermal shock Power OFF To be done 10 cycles with the following condition
(To be measured after leaving samples for 1 h at normal temperature and humidity after the test.)
80 °C 0.5 h、− 20 °C 0.5 h

Additional Information


※The click spot is located somewhere outputs A & B are at Lo level.


Single shaft and PIN HEADER



Single shaft and SOCKET

Double shaft and SOCKET



Option(Snap-in Holder)

❖ Available mounting on PC board with Snap-in Holder as an optional item separately.

❖ With Snap-in Holder


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