Reed sensor

Europe has been the biggest market up to now. Future applications will be in environmental protection and security e.g. water-meters and door detection devices. We expect an increase of appr. 15% p.a. The US market shows a delayed response. It might reach the present-day European level of appr. 25 million reed sensors p.a.in 10 years time. Asia the market is growing at an above-average rate. We expect annual increases of 20%. 

Dropping the reed switch or a reed sensor on a hard object, typically on the floor of a manufacturing facility, can induce a damaging shock to the reed switch. Shocks above 200 Gs should be avoided at all cost (see Fig. 5.18). Dropping any of the above on a hard floor from 20 cm or more (more than one foot) can and will... 

The containers for water softener and clarifiers are situated in the door of the dishwasher. The reed sensor is mounted next to the plastic casing that contains a magnet in a protective foam housing, floating on the liquid. When the level drops to a certain point, the floater activates the reed sensor, which in turn directly operates an indicator light on the front panel. The operator of the dishwasher is then alerted that softeners and/or clarifiers need to be refilled. 

Another application for reed sensors in modern dishwashers is within the spray-arm control device. This application is very important in protecting the dishes, and even the dishwasher itself, from damage. 

A reed sensor is mounted either above or underneath the spray-arm, outside of the washing area, while a magnet is placed on the spray-arm. The reed sensor counts the revolutions of the spray-arm. If for any reason the spray-arm is not working (Dishes inside the dishwasher could block the movement, or the spray-arm is faulty, etc.), the sensor will indicate on a small outside light or display that service is needed. An additional electronic device could also be activated with this reed sensor to stop the machine, so that the dishes or the machine itself will not be damaged. 

Commercial laundry dryers can not be easily vented to the outside in the same way that home laundry dryers are. Because of this fact, the moist air is passed through a condenser where the water will accumulate. If there is no direct water drain, the water is directed to a holding tank. The water level is monitored using a magnetic float. When the water rises to the full level, the reed sensor is activated and shuts down the dryer. Once the water is removed, the reed sensor is deactivated, enabling the dryer to operate. 

The reed sensor is usually mounted in the chassis of the appliance and the permanent magnet is placed in the doorframe. Thus, when the door is closed, the magnets position is above or parallel to the sensor. When someone opens the door, the circuit is broken. 

Lately, we have noted that SMD reed sensors are preferred for this type of application. 

To replace the old-fashioned eye-control method of detecting the level of the liquid, appliance manufacturers now use reed sensors to show when the container for Jet-Dry needs refilling. The reed sensor is mounted underneath, or next to, the liquid container. A floater with an internal permanent magnet is placed in the container and floats on the liquid. If its level falls to a minimum, the floater activates the reed sensor which, in turn, activates a light on the front control panel of the dishwasher, signaling the need to refill the Jet-Dry container. 

Massage chairs, special lifts for bathtubs, hospital beds, etc. all have electronic adjustments that can be controlled by reed sensors. In applications like these, no special voltage or current is necessary. Therefore, there is no risk of dangerous electric shock. 

Reed sensors are often used as end position sensors. The reed sensor is mounted at the end position for a given movement. A magnet is strategically placed or mounted on the moving part. When the magnet approaches the reed sensor, it activates and triggers the appropriate circuitry, which in turn stops the movement. 

Instead of sensing only the end position, it is also possible to monitor different positions for movement. For this purpose, several reed sensors are mounted at the various positions requiring sensing. When the magnet passes these positions, they are registered by the sensors. Several magnets could also be used with one sensor as an alternative. If the positions and motions are complex, a combination of both is also possible. 

Robert-Bosch-Strasse 4 Fax 07731-839932 Reed Sensor Sensor... 

MEDER MEDER electronic AG Friedrich-List Strasse 6 D-78234 Engen-Welschingen MEDER electronic Inc. 766 Falmouth Rd Mashpee, MA 02649 Reed Sensor ... 

The source for replacement Figure 3.16 should be ATEX (http //WWW. aet. f r/e n/p rod u I t-ATEX Junction box G RP321. html) The source for replacement Figure 3.17 should be Reed Sensors (www.reed-sensor.com/)... 

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