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The LM34CAZ is ideal for cold-junction compensation(CJC) temperature measurements. Customers who... more
Price:
$12.00

The LM34CAZ is ideal for cold-junction compensation(CJC) temperature measurements. Customers who are using thermocouples on an external CB37 terminal board can wire this sensor to a nearby analog input, and correlate the CJC offset within software. Simply connect +Vs to LabJack VS, GND to LabJack GND, and Vout to a LabJack AIN terminal (FIO/EIO is best on the U3). It has a very convenient output of 10mV per °F, so 0.78V would correspond with 78°F.

  • TO-92 Package
  • Typical Accuracy ±0.4°F
  • Operating Range 0°F to +230°F (-17 to +110 °C) when powered by 0/5 volts.
  • Output Voltage 10mV/°F
  • See LM34 Datasheet for Complete Specifications

The LM34CAZ is the most accurate version of the LM34 precision temperature sensor made by Texas Instruments; it is not manufactured by LabJack, so the LM34 datasheet is hosted by Texas Instruments. Some soldering may be necessary to add length to the sensor wires. For more details about this sensor and a detailed look at different kinds of temperature sensors, see our temperature sensor app note.

How about the LM35?

Note that even if you want to measure in Celsius, the LM34 is better than the LM35 because you get more voltage per temperature (18 mV/°C versus 10 mV/°C) and you can measure lower with a single supply (-17 °C versus +1 °C).

Adding a Cable

Very little current is flowing, so any type of signal cable will work fine.  The LM34 output can easily go unstable when presented with capacitive load, so regardless of cable length we always recommend a 10k resistor from Vout to GND (preferably right at the sensor), and this is usually good for cables up to 25ft.  This increases the current draw of the sensor from the typical 75 μA up to a few hundred μA (additional current is output voltage/10k).  Beyond 25ft see the "Capacitive Loads" section in the LM34 datasheet and consider adding a series resistor.

Local Temperature

One of the pictures above shows an LM34 plugged directly into a screw terminal block.  Not only is the sensor package close to the screw terminal, but the short leads will readily conduct heat between the screw-terminal and the inside of the LM34, thus this will give you a very good reading of the temperature of the screw terminal (good for cold junction compensation).

Screw terminals on a passive device, such as the CB37, will be the same temperature as the surrounding air.  So the LM34 will read the same whether plugged right into the screw terminal or with a short cable added.

Screw terminals on an active device, such as the T4/T7, will be warmer than the surrounding air due to the power consumption of the device.  For example, the typical temperature rise of a T4/T7 with USB & Ethernet enabled is 4.9 °C.  An LM34 plugged directly into a screw terminal on the T4/T7 will read warmer than ambient.

Cold Junction Compensation

The main reason we sell this sensor is to measure the temperature of a thermocouple's cold junction so cold junction compensation (CJC) can be done.  The voltage produced by a thermocouple is related to the difference in temperature between the remote end and the local end, so for CJC you need to know the temperature of the local end of the thermocouple.  For example, if a thermocouple is connected to a screw-terminal block on a CB37, you need to know the temperature of that screw-terminal block (which with the CB37 is typically the same as ambient).

One of the pictures above shows an LM34 plugged directly into a screw terminal block.  Not only is the sensor package close to the screw terminal, but the short leads will readily conduct heat between the screw-terminal and the inside of the LM34, thus this will give you a very good reading of the temperature of the screw terminal.  Note in the picture that the leads have to be bent awkwardly ... we suggest putting little pieces of electrical tape between the leads to keep them from touching each other, and recommend you have extra LM34s as the leads break off easily if over manipulated.  We just sell the LM34CAZ as a convenience for customers, and our feelings are not hurt if you buy them from a less expensive source.

 

LM34CAZ: 12.00
Uses two digital lines on any LabJack to retrieve temperature and relative humidity measurements.... more
Price:
$79.00

Uses two digital lines on any LabJack to retrieve temperature and relative humidity measurements. Featuring the Sensirion SHT11 sensor, it provides 14-bit temperature readings and 12-bit humidity readings. An enable line is provided to allow multiple EI-1050 probes to be connected to a single LabJack.

  • Temperature Range: -40 to +120 °C
  • Temperature Accuracy: ±0.5 °C @ 25 °C
  • Humidity Range: 0-100 %RH
  • Humidity Accuracy: ±3.5 %RH
  • Made by Electronic Innovations Corp.

For more information, see The EI-1050 Datasheet and our optional Testing/Setup Utility.

EI1050: 79.00
Easy to use and very accurate temperature probe from Electronic Innovations Corp. Features a... more
Price:
$57.00

Easy to use and very accurate temperature probe from Electronic Innovations Corp. Features a waterproof stainless-steel probe, a high-level linear output of 10 mV per degree F, a typical accuracy of ±0.4 degrees F (±0.22 degrees C) at room temperature, and a range of 0 to +230 degrees F (-17 to +110 degrees C, with U3/UE9).

For more information, see The EI-1034 Datasheet.

EI1034: 57.00
Easy to use and inexpensive temperature probe from Electronic Innovations Corp. Features a plastic... more
Price:
$33.00

Easy to use and inexpensive temperature probe from Electronic Innovations Corp. Features a plastic probe, a high-level linear output of 10 mV per degree K, a typical accuracy of ±1 degrees C (±1.8 degrees F) at room temperature, and a range of -40 to +100 degrees C (-40 to +212 degrees F).

For more information, see The EI-1022 Datasheet.

EI1022: 33.00
Provides 16 industry standard relay module sockets to a LabJack U12. Image shows RB16 with... more
Price:
$119.00

Provides 16 industry standard relay module sockets to a LabJack U12. Image shows RB16 with standard and miniature modules installed. The RB16 provides a versatile method for electricians, engineers, and other qualified individuals, to interface a LabJack U12 with high voltages/currents.

I/O modules are available from a variety of manufacturers such as Grayhill, Crydom, or Kyoto, and allow the LabJack U12 to control or monitor 120/240 VAC and/or 3-60 VDC. The following Grayhill modules are available for purchase from Digikey: 70M-OAC5 (AC output), 70M-ODC5 (DC output), 70M-IAC5 (AC input), 70M-IDC5 (DC input).

  • Relay modules are NOT included
  • Modules are available with voltage ratings up to 200 VDC or 280 VAC, and current ratings up to 3.5 amps
  • DB25 cable is included
  • Made by Electronic Innovations Corp.
  • LabJack U12 only. See the RB12 for other devices

Note: The user can also install a resistor to bypass each socket and pass through the standard digital I/O line.

For more information, see the RB16 Relay Board Datasheet.

RB16: 119.00
General purpose dual instrumentation amplifier. Often used in conjunction with the LabJack U12 to... more
Price:
$126.00

General purpose dual instrumentation amplifier. Often used in conjunction with the LabJack U12 to provide analog input gain. Operates from a single 5 volt supply and provides a ±15 volt supply and a 4.096 volt reference voltage. Analog input range is ±10 volts. The gain of each channel is set to 1, 10, 100, or 1000 via digital I/O or jumper wires.

For more information, see the EI-1040 Dual Instrumentation Amplifier Datasheet.

EI1040: 126.00
Provides screw terminal connections for the LabJack U12's 16 extra digital I/O. A screwdriver and... more
Price:
$39.00

Provides screw terminal connections for the LabJack U12's 16 extra digital I/O. A screwdriver and DB25 cable are included. For the LabJack U12 only.

For more information, see the CB25 Datasheet.

CB25: 39.00