霍尔传感器受EDI和 RFI 影响，需加以防护。干簧和emr 传感器不受 EDI或RFI影响。
一般霍尔传感器的运行时间是5 µs, 干簧传感器是 100µs emr 可达10 ms。
Yes, they only supply a small milli-volt signal in the presence of a magnetic field. The signal needs to be amplified and then fed into a switching circuit.
A voltage is produced on a semiconductor material when in the presence of a magnetic field. The voltage is proportional to the strength of the magnetic field.
霍尔传感器的释放时间通常为5μs，干簧管传感器为20μs和 emr 5毫秒。
霍尔传感器不能切换任何输出电流，干簧管传感器和emr 通常可以直接切换高达2 A。
电流10-50毫安，切换5-15V , 我该选择哪款干簧产品？
电流10-250毫安，切换15-35V , 我该选择哪款干簧产品？
For a sensor use the ORD228 with iridium or the ORD2210 for a relay.
Miniature reed switches less than 20 mm (0.80 inches) glass length can effectively break up to 250 Volts. This depends on the pull-in AT (mT) used. The higher the better. Reed switches less than 10 mm will shrink this value to around 150 volts. Minimizing the current flow at the time of opening will improve this value.
Reed switches whether they are used in sensors or relays all will be asked to switch some load. Generally there are two aspects to this load.
- Its steady state load
- Is the actual switching taking place during the first 50 nanoseconds. This is also called the signature of the load.
This signature takes into consideration not only the steady state load but also any transient voltages or current that may be present during the first 50 nanoseconds. These transients may be from stray capacitance, inductance in the line and/or common mode voltages. From a reed switch designer standpoint, the signature is all there is. The most important time during the switching of a load is that first 50 nanoseconds. That is when all the damage to the contacts with occur if you are switching the contacts ‘hot’. If a customer is having a problem with early failures, this is the first place to look. Equally important and not to be overlooked is what voltage and current is actually being broken when the contacts open. Any healthy voltage and/or current present will chew up the contacts rapidly leading to sticking reed contacts.
There are several key factors:
- You need to have an idea of the required load. What voltage and current is being switched at the time of closure for the first 50 nanoseconds?
- How many operations will be required during the life of the product?
- What are the size requirements? How much room is needed?
- How will the product be mounted? Surface mount, thru hole, etc.
- For long life and low levels, use a ruthenium or an iridium sputtered/plated switch.
- For switching applications from 50 Volts to 200 volts use the Philips/Coto/Comus sputtered ruthenium switch.
- For switching currents 25 ma to 1 amp, the KOFU thickly plated rhodium is good along with our KSK-1A35.
- For higher voltages above 200 volts up to 4000 volts at relatively low current use the OKI ORD2210V.
- For voltages above 1000 volts up to 10,000 volts with higher currents use the Hermetic vacuum switches. This represents a start. One could write a book on this subject. Best to find out the exact customer load and run a life test with a few or several reed switches to make the final determination.
A magnet and reed switch can be turned into a temperature sensor by using a magnet that has a certain curie temperature for the temperature you want to sense. When that curie temperature is reached the magnet loses its magnetic properties whereby the reed switch contacts open. When the temperature drops below the curie temperature, the reed contacts will close.