LLAC4 4-Channel Low-Level AC-Conversion Module
Expands Capacity
Increases number of signals datalogger can monitor
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The LLAC4 is a small peripheral that you can use to increase the number of low-level ac signals that your datalogger can monitor. The LLAC4 is often used to measure up to four anemometers, and it is especially useful for wind profiling applications.

Read More

Benefits and Features

  • Ideal for applications that require high numbers of pulse channels, but fewer control ports, such as in wind prospecting


Detailed Description

The LLAC4 enables four datalogger control ports to emulate pulse-counting channels by converting the low-level ac signals to logic levels read by the control ports. To use the LLAC4, the datalogger control ports must accept high frequency pulses. The LLAC4 typically measures anemometers but can measure other sensors that output pulse counting signals. 

Minimum AC Input Voltage versus Output Square Wave Frequency

Input Sine Wave
(mV RMS)
Output Range (Hz)
20 1.0 to 20
200 0.5 to 200
2000 0.3 to 10,000
5000 0.3 to 20,000


Power 0.1 mA (@ 12 Vdc)
AC Coupling Removal of DC Offset up to ±0.5 V
Input Hysteresis 16 mV (@ 1 Hz)
Maximum AC Input Voltage ±20 V
Cable Length 0.6 m (2 ft)
  • 5.4 x 8.0 x 2.5 cm (2.1 x 3.1 x 1.0 in.) without base mounting flanges
  • 5.4 x 11.2 x 2.5 cm (2.1 x 4.5 x 1.0 in.) with base mounting flanges
Weight 92 g (3.2 oz)


Datalogger Considerations

The LLAC4 works only with dataloggers whose control ports can accept high frequency pulses. The CR23X has four control ports that can be used (5, 6, 7, and 8); the CR200X-series control ports are compatible but are limited to inputs of 1 kHz.

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X CR6 Series CR300 Series

*It is necessary to use the CR9071E module with the CR9000X and LLAC4.

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000 CR7X


The LLAC4 typically measures anemometers. Compatible anemometers include the Wind Monitors, 03002 Wind Sentry Set, and 03101 Wind Sentry Anemometer. (The 014A Anemometer and 034B Windset are not compatible.) The following anemometers are compatible.

#40C 014A 03101 03002 034B 05103 05103-45 05106 05305

The LLAC4 can also measure other sensors that output pulse counting signals.

Frequently Asked Questions

Number of FAQs related to LLAC4: 1

  1. No. But using a LLAC4 will convert the ac signal for up to four 03101-L sensors (and other ac output anemometers) to individual 0 to 5 Vdc TTL level square wave outputs. For more information, see the LLAC4 specification information

Articles and Press Releases

Blog Articles