This product is discontinued.




The AR-7240B is an analog engine tachometer featuring the automatic full scale switching function. When engine rotation is measured in the low scale, such as idling speed adjustment, it can be observed in the low range with 200 r/min scale. And the meter scale can be switched automatically to the high range with 10,000 r/min scale when engine rotation is increasing up into high speed load domain.

For gasoline engine measurement, the IP ignition pulse detector (for primary or secondary side) can be set up byseries one-touch attachment. For diesel engine, the VP-202/VP-1220 detector can be used. In addition to AC power supply, optional DC power supply is available and enables the AR-7240B on-board use or any place to measure. The analog output helps to figure out fluctuation of rotation speed, and pulse output can be applied to process the number or cumulated rotations of ignitions.


  • The most appropriate detector according to the type of engines under test can be selected by switching operation.
  • A variety of engine rotation detector can be available in combination, for 2/4-cycle engines having from 1 to 8 cylinders.
  • The number of input pulses per rotation can be set in a range from 0.5 to 199.5 pulses in 0.5 steps.
  • Provides analog and pulse outputs as standard.
  • The pulse output can be selected from 1 P/R or 60 P/R, or a wave-shaped output of an input signal.
  • Optional DC power supply enables the AR-7240B on-board use as well as engine bench.
  • Equipped with upper and lower limit alarm output, enabling protection from damages on the engine under test.

Overview Specification

Applicable detectors (option) IP-292/296/3000A/3100, OM-1500/1200, VP-202/1220, MP-9100/981, LG-916, TTL
Measurement range 400 to 10,000 r/min (The upper limit of rotation depends on a detector and setup of input pulse switching.)
Input pulse switching 0.5 to 199.5 P/R (in 0.5 P/R steps, depending on a detector)
Trigger level IP-292/296/3000A/3100, OM-1200, VP-202/1220:settable using dial-type potentiometer
MP-9100/981, LG-916, TTL:internally adjusted and fixed
Meter 110mm square wide angle meter (low/high/automatic switching))
Measurement scale 0 to 2,000 r/min (red) 20 r/min per 1 scale
0 to 10,000 r/min (black) 100 r/min per 1 scale
Analog voltage output * 0 to 5 V / 0 to 10,000 r/min (Can be changed to 0 to 1 V / 0 to 10,000 r/min as an option.)
Load resistance: 1 kΩ
Linearity: ±0.5% / F.S. max.
Output adjustment range: ±4% /F.S. max. (zero), ±4%/F.S. max. (span)
response time: approx. 80 ms or less/10 to 90% (when no signal input, the response will delay by 3 to 4 seconds.
Pulse output 1 P/R, 60 P/R (asynchronous to the input signal)or wave-shaped output of the input signal
TTL level, fanout 2
Contact output Run judge: 1 to 99 × 100 r/min
Overrun: 1 to 99 × 100 r/min
Comparison interval; every 100 ms
Transfer contact, contact capacity: resistant load 240 VAC / 2 A , 30 VDC / 2 A
Power requirement 100 to 240 VAC ± 10%, approx. 25 VA (option: DC 11 to 15 VDC, approx. 13 VA)
Operating temperature range 0 to +40 °C
Outer dimensions 210 (W) × 149 (H) × 300 (D) mm
Weight Approx. 4 kg
Accessories ・AC power cable (1.9 m), fuse

*Current output can be optionally modified (0 to 10mA/0 to 10000r/min).
(The voltage output is not available when the current output is provided.)




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