Analog Magnetic Stirrer

What is the Analog Magnetic Stirrer?

An analog magnetic stirrer uses a rotary knob to set motor voltage and therefore stirring speed, without digital display or feedback. It is the economical choice for routine mixing of buffers, solutions and low-viscosity samples where exact rpm repeatability is not required.

Overview

The analog magnetic stirrer is the simplest and most common format. A DC or shaded-pole motor spins a magnet assembly, and a potentiometer knob adjusts voltage to change speed. Typical units cover roughly 100 to 2,000 rpm, handle up to about 5 L of water-like liquid, and use an aluminum or ceramic-coated top plate. Because there is no closed-loop control, actual speed shifts slightly with load and supply voltage, so the scale on the knob is a guide rather than a measurement. This format suits teaching laboratories, routine reagent preparation and any application where visual adequacy of mixing is enough. Fewer electronic components mean easy maintenance and lower cost, and many users keep several units across the laboratory.

How does it work?

A magnetic stirrer contains a motor-driven permanent magnet, or a set of electromagnets, beneath a flat work surface. As the magnetic field rotates, it couples to a PTFE- or glass-coated stir bar placed in the vessel and pulls the bar into synchronous rotation, which creates a vortex and mixes the liquid. Speed is set by varying motor voltage or by pulse-width modulation, and digital models add a tachometer feedback loop to hold rpm constant. If the load or viscosity is too high, the bar decouples from the field and spins erratically. Bar shape, length and surface finish influence mixing efficiency, and larger bars couple better at high volumes. The work surface may be aluminum, stainless steel or glass-ceramic, chosen for chemical resistance and cleanability.

What are the key features?

• Rotary knob speed control with simple and intuitive operation
• Chemically resistant ceramic-coated or anodized aluminum work plate
• Brushless or low-maintenance DC motor for continuous operation
• Soft-start to reduce stir bar decoupling at low speeds
• Compact footprint that fits inside fume hoods and on crowded benches

What are the technical specifications?

A typical analog magnetic stirrer configuration offers speed range of 100–2,000 rpm, max stirring volume (water) of 5 L, speed control of Analog knob, open loop, motor type of DC motor, work plate size of 135–180 mm diameter and plate material of Ceramic-coated aluminum. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Analog Magnetic Stirrer is used in teaching laboratory demonstrations, routine buffer preparation, dissolving salts and reagents and simple titration mixing. Across the wider Magnetic Stirrers class, laboratories also deploy it for buffer and reagent preparation, titration sample mixing and cell culture media preparation.

Which standards and certifications apply?

Relevant standards and methods include IEC 61010-1, IEC 61010-2-010, IEC 61326-1, GB 4793.1 and ISO 9001. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Place the stirrer on a level, vibration-free surface and keep liquids away from the vents. Start at low speed and increase gradually so the bar does not decouple and strike the vessel wall. Clean PTFE bars and plates after use, and inspect bars for chips or contamination that might carry over between runs. Magnetic fields can affect pacemakers, magnetic media and sensitive electronics, so set safe distances. Periodically verify rpm with a tachometer and record the result in the equipment log. For regulated work, include the unit in the preventive maintenance and qualification program, and check that electrical safety testing complies with IEC 61010-1 and your local requirements.

How do I select the right Analog Magnetic Stirrer?

Select the analog model for routine, non-critical mixing where a displayed speed is unnecessary and budget or simplicity matters. Choose a digital model when rpm must be recorded or reproduced. In an RFQ, specify the maximum volume, viscosity, plate diameter, voltage and plug type, and whether spark-free operation is needed.

How does it compare with other Magnetic Stirrers variants?

Decide first on maximum liquid volume and viscosity, because these set the magnet strength and the largest bar that will stay coupled. Then choose between analog control, which is economical and adequate for routine mixing, and digital control with a rpm display and closed-loop regulation, which is preferred when repeatability matters. A slim profile helps where space is tight or when stirring inside hoods, while a submersible format suits incubators and cold rooms. Check speed range, particularly the low end for gentle mixing of cell cultures, plus the working surface material, IP rating of the housing and ambient temperature limits. For sensitive samples, verify that the motor does not transmit significant heat to the vessel. Specify voltage, plug type and any required explosion-protection features in your RFQ.