Constant current source

The Lake Shore 121 programmable DC constant current source from the United States is a high-precision DC power supply that can be used in laboratories, testing institutions, and production environments. It can be used on workbenches or installed in test cabinets through panels. Its output current is as high as 100mA, with low noise. It can be manually selected from 13 output ranges to choose the appropriate range. When a constant current source is connected to a load resistor, the power changes by 10 times for each range change.

Introduction to Hengliu Source Products

The Lake Shore 121 programmable DC constant current source from the United States is a high-precision DC power supply that can be used in laboratories, testing institutions, and production environments. It can be used on workbenches or installed in test cabinets through panels. Its output current is as high as 100mA, with low noise. It can be manually selected from 13 output ranges to choose the appropriate range. When a constant current source is connected to a load resistor, the power changes by 10 times for each range change. Users can choose the appropriate range within the range of 100 nA to 100 mA.

Automated operation can be achieved through the USB computer interface of the instrument, which can control 121 to output the desired current and achieve automated operation. Therefore, specific application patterns can be created.

The working voltage of this instrument is 5V DC voltage, and the standard 211 constant current source is equipped with an external wall mounted AC power supply. The voltage range of the AC line can be applied from 100 VAC to 40 VAC, 50 or 60 Hz. The power supply will automatically apply AC voltage ranging from 100V to 240V, 50Hz to 60Hz.

Main characteristics of constant current source

6 sets of decimal output currents, 13 selectable ranges

Programmable current output, ranging from 100nA to 100mA

Low noise output

• 3-digit LED display

• Simple user interface

• Reverse current function

USB interface allows integration with automated testing systems

DIN front panel installation package

• Detachable output terminal block

• CE certification

Constant current source application

The 121 type current source is suitable for testing, measuring, and operating resistors and semiconductor devices, such as:

• Lake Shore Cernox ™ temperature sensor

Other resistance temperature sensors (RTDs), such as platinum sensors

• Diode temperature sensor, including Lake ShoreDT-670S

LED devices

Hall sensors for magnetic field measurement

A stable constant current source is a key factor in ensuring the continuous operation of devices, and the voltage drop of these devices depends on temperature, magnetic field, and other parameters. When using a constant current source in conjunction with a resistive sensor, the constant current source's wide current output range is valuable because the sensor's resistance can vary significantly by six orders of magnitude with temperature. The current reversal function can compensate for thermoelectric potential, which is important for high-precision resistance measurements that require very low excitation currents. Application examples include:

Basic component quality inspection ("good/bad" inspection)

LED brightness test (constant device current)

Temperature sensor calibration (determining the resistance at a fixed calibration point)

• Temperature measurement (through voltage readings)

Calibration and measurement of magnetic sensors

Measurement of semiconductor devices (diode, transistor IV curve)

• Circuit prototype (fixed current source)

• Small scale electrochemical applications

Whether establishing sensor calibration under a wide range of environmental conditions or conducting simple device consistency testing, the 121 constant current source is a convenient and reliable alternative to simple voltage circuits, as well as a practical way to replace expensive multifunctional current sources. By utilizing its USB computer interface, the 121 constant current source can be easily integrated into automated testing systems and provide a high-speed, readable, and easy-to-use display interface.