Custom Hall Effect Sensor Design Considerations

Power Supply:

• What power supply voltages are available for the sensor?
• Is the power supply stable?
• Are there solenoids, actuators, relays, or other components in the electrical system that can cause voltage surges, current spikes, or EMI in the electrical system

Sensor Output Type:

• What inputs are available in the control and monitoring system (NPN, PNP, TTL, Relay…)?
• Are there minimum or maximum output voltages for the high and low output states?
• Are there concerns of EMI between the sensor output and the control system?
• Is there potential for voltage or current to flow backward into the sensor through the output?
• Does the output have power rating requirements for switching relays, powering LEDs, or driving other electronics within the electrical system?

Custom Electrical
Functions:

• Does the application require one digital switching output, multiple digitals outputs, a proportional analog output, or a combination of digital analog outputs?
• Are there target behaviors the sensor should ignore?
• Are there requirements for specific duty cycles or phase angle between outputs?
• Are there requirements for sensor output state at power up?

Application Examples with Custom Electrical Requirements:

• An OEM automotive equipment manufacturer uses a CPU that requires the speed pulse output states to be above 0.5V in the low state and below 4.5V in the high state to differentiate the pulse trains from electrical system failures where the output is pulled to ground or Vcc.
• An application specific custom vehicle needs to provide power to a PTO only when the drive shaft is spinning in a specific direction and above a defined minimum speed. The sensor provides a relay output is only closed when both speed and direction requirements are being met.
• In the original design a manufacturer of aftermarket performance equipment was adding flyback diodes into the wiring harness behind a speed sensor. The redesign moved the protection inside the sensor itself for a more durable and lower cost solution.
• A position sensor detects when a feature on a moving target passes the sensor face, but the control system requires a pulse length that is of a minimum length that is longer than a pulse provided by a Hall Switch or Gear Tooth Sensor measures. The custom sensor provides a “one-shot” pulse of a defined length regardless of how fast the target passes the sensor face.

Mounting Style: Threaded Barrel vs. Flange

Hall Effect Sensors are typically provided with either a threaded barrel and lock nuts or have a flange with one or more holes for mounting. We can provide custom sensors using any of our hundreds of existing stainless-steel, aluminum, and plastic options, or we can design a new housing specific to your application.

The following should be considered when determining which type is best for a new application.

• Threaded barrel housings can be either threaded into a port or mounted to a simple bracket using lock nuts.
• Threaded barrel housings allow for easy adjustment of sensor orientation and gap to the target during installation.
• Special requirements exist for threaded barrel housings that are sealing into pressurized applications.
• Flange mount housings offer the quickest installation for guaranteed orientation and setting of gap.
• Flange mount housings can be provided with o-rings for sealing the sensor into pressurized applications.
• Flange mount housings allow the option to have the electronics parallel to the target to minimize the distance between the target and the back of the sensor.

Housing Size & Shape:

Whether the concern is a minimum length, a maximum length, an existing bore diameter, or necessary features for holding the sensor when mounting there may be multiple aspects of the shape and size of the housing to be considered when designing a custom sensor.

Consider the following if a custom housing design is required.

• The functional range of the sensor may determine a minimum length for a sensor to be both mounted and in range of the gear, magnet, or another target. Flange mount housings allow for a fixed installation gap guaranteeing the same gap between the sensor face and mounting location.
• In some applications, the space where the sensor can be mounted to detect the target may be limited by other components of the assembly. Determining a maximum length should always consider the type of connection and how it will exit the housing to ensure the sensor will fit when installed and that cabling is not bent beyond the minimum bend radius.
• In other applications, a sensor may be mounted into a port or other existing feature that defines either a sensor barrel diameter or specific thread pitch. Be sure when specifying thread requirements to identify the complete thread details (diameter, pitch, and class) to ensure sensors are built to properly mate into existing threads.
• In applications where the sensor is sealing into a pressurized motor or another assembly with a smooth barrel and an o-ring, the housing diameter, bore diameter, o-ring groove dimensions, pressure, and temperature range are all factors in determining the correct o-ring requirements.

Housing Material:

Standex Detect provides a wide variety of sensors in housings made of stainless steel, aluminum, and plastic. We also have applications where sensor housings have been made of titanium and zinc. Other materials can be considered for applications as long they will not affect the magnetic fields being detected.

• Stainless Steel housings are used in many applications where the sensor housing needs to be robust against harsh environmental conditions. Typically, they are composed of 303 Grade Stainless, but 304 Stainless is also available. We have these housings machined to our specifications in any volume and we can typically have new custom stainless-steel housings made to order in approximately 3-4 weeks.
• Anodized Aluminum housings are a more cost-effective, lighter weight alternative to stainless steel. At moderate to high volumes, they can also be more cost-effective than molded plastics once tooling costs are factored in. Typically, we provide aluminum housings with a black anodization, but other colors are also available.
• Plastic housings are the lowest cost solution for high volume OEM applications. We offer a handful of options in flange mount and threaded plastic housings that are made of glass filled nylons that are suitable for under the hood and vehicle undercarriage applications. Dependent on the specifics of the design a custom molded plastic housing may be cost-effective at volumes of around 5,000 pieces, but tooling can be $20,000-$40,000 dependent on the housing shape, size, and the number of mold cavities.

Other housing materials are available. We have designed custom titanium housings for use in specific applications where material interactions were a concern and we have also provided zinc casted housings to provide lower cost sensors for applications with volumes of less than 5,000 per year.

Connection Type & Cable Protection:

We offer a wide variety of connection types to meet the needs of different applications. For custom sensors, we can provide free end wires or cables, connection pigtails, and integrated connectors dependent on the needs of the application.

Our connection types are separated into the following categories.

• Free End Wires are the lowest material cost solution and are offered with PVC, XLPE, or Teflon Insulation. We can provide wires to any defined length, and these connections allow easy wiring when output wires are run to a different location than the power and ground wires.
• Jacketed Cables are also available in a variety of insulation and jacket materials dependent on the needs of the application. They can be provided in any required length with custom jacket and insulation stripping available.
• Shielded Cables are also available in a variety of insulation and jacket materials dependent on the needs of the application and options are available for either foil shields, braided shields, or both. They can be provided in any required length with custom jacket and insulation stripping available.
• Ribbon Cables are available for our 3 wire sensors and are another low-cost solution. The insulation is bonded together for easily running the wires, but they can be separated as well.
• Integral Connectors are available allowing for quick connection/disconnection of sensors at the mounting location. We offer M12 integral connectors as well as a variety of MS style integral connections for a wide variety of applications. Whether an integral connector can be used in an application is dependent on the form factor of the sensor housing.
• Pigtail Connections are offered with a wide variety of connector types including Deutsch, Amphenol, Amp, Paccard, and MS style connectors. They can be built to any length required and with the wire/cable types as appropriate for the application.

Additional protection over individual wires or cables can also be added to any sensor type. We can protect wires with corrugated tubing, fiberglass sleeving, rubber hoses, or flexible conduit integrated directly into the sensor. We can also add mounting clips or design features into the sensor housings to allow for EMT to be run over the cable all the way to the sensor.

Sensor Target Details:

• In addition to custom features of the sensors themselves, in many applications the target the sensor is detecting may also be custom to the application. Custom targets may include steel or magnetic features used in counting, speed measurement, and position detection applications.
• We offer the following application note with detailed information on designing custom ferrous metal sensor targets: Selection and Design of Sensor Targets.

Custom Labeling & Packaging:

• Our Hall Effect sensors are engraved with part number and date code information so that we can quickly identify the production lot of every sensor built. For custom applications, we can provide customer part numbers/names/logos on the sensor as an alternative to our own.
• In addition to custom labeling on the sensors we can also kit sensors with accessories such as brackets, o-rings, and mounting hardware and apply customer-specific labeling on sensor bags and boxes. We can also provide barcode labels for easy scanning in and out of inventory.

Application Examples with Custom Mechanical Requirements:

• Engine Sensor Replacement – An engine manufacturer needed a speed sensor compatible with a different ECU than the OEM offering. Standex Detect developed a replacement sensor with an anodized aluminum housing that matched the existing mounting interface while simplifying non-critical housing features to reduce overall cost.
• Ruggedized Threaded Sensor Design – A customer using low-cost molded sensors experienced frequent failures due to vibration and mechanical stress. Standex Detect redesigned the sensor with a robust aluminum housing, full reed switch encapsulation, extended threads for easier installation, a longer cable to eliminate an electrical junction, and a more reliable sensing element, significantly improving durability and performance.
• Heavy Equipment Speed and Direction Sensors – When a supplier ceased production of custom speed and direction sensors, Standex Detect assumed manufacturing and reduced unit costs. Working closely with the customer, we further improved durability, ease of installation, and manufacturing efficiency. Sensors are delivered in custom brackets, individually kitted with barcode labels, and paired with custom cable sets marked with customer part numbers for easy identification.
• Oil Tank Thief Hatch Monitoring – An energy company sought a reliable solution to detect whether oil storage tank hatches were open or closed. Standex Detect developed a sensor integrated into the hatch latch with a custom magnetic target and later introduced an alternative configuration based on customer feedback. Today, both patented Thief Hatch Detection System designs provide a reliable, cost-effective solution compatible with a wide range of wireless transmitters.

Regulatory Requirements & Certifications Needed:

Dependent on the industry and application, there may be specific regulations placed on sensors requiring proof of compliance to standards or even external certifications and lab testing. When an application has these types of requirements such as “Explosion Proof”, “RoHS Compliant”, or meeting specific UL, CSA, or other standards please be sure to provide this information at the start of the project. This way the requirements can be considered in the mechanical and electrical design and testing of the sensors as well as for determining the costs of production sensors.

• RoHS Compliance – we currently offer some, but not all of our products as compliant. Dependent on the sensor type and electrical options we may need to have compliant versions of the circuitry and connection assemblies created. The associated costs can be paid as an upfront tooling cost or amortized into the first production run.
• CE Compliance – with the Low Voltage Directive and some other options Sensor Solutions can often perform the necessary testing and documentation internally. For other CE, UL, CSA, and other standards external testing and certification may be required. Over the years Sensor Solutions has had many products certified to meet requirements specific to an application. We work with several highly qualified test labs and send a Design Engineer to be there during testing to oversee the process and minimize potential issues or questions that can delay or increase the costs of testing.

Application Examples with Custom Regulatory Requirements:

• Furniture Lighting Safety Sensor – A Murphy Bed manufacturer needed a sensor and magnet to control LED lighting based on whether the bed was open or stored in the wall. After extensive validation testing, the customer requested confirmation of compliance with furniture industry electrical requirements. Standex Detect verified compliance and satisfied labeling requirements through a simple cable labeling update.
• Regulatory Testing Cost Reduction – An agricultural equipment manufacturer required sensors to meet extensive regulatory and application-specific testing standards. During the design phase, Standex Detect identified which tests could be completed in-house and which required third-party certification, helping the customer save thousands of dollars in testing costs.
• Hazardous Location Thief Hatch Detection – An energy company needed a reliable way to monitor whether oil storage tank hatches were open or closed in hazardous environments. To avoid costly intrinsic safety certifications, Standex Detect designed the sensor to meet Simple Apparatus requirements, delivering a compliant, reliable, and cost-effective solution. Learn more about our Thief Hatch Detection Systems here.

Examples of OEM Replacement Sensor Applications:

• An aftermarket automotive component provider originally contacted Standex Detect to provide a simple sensor with a length of jacketed cable. After a discussion with the customer, it was determined that they were not only adding a connector and protective tubing to the sensors, but they were also adding an external diode in the connector to prevent the electrical system from damaging the sensors. The Standex Detect replacement sensors now have the protective diode inside the sensor itself and the company now purchases the sensors ready to deliver to their end customers with no processing in their facility at a reduced cost.
• A manufacturer where Standex Detect originally replaced the OEM source due to pricing and minimum purchasing concerns acquired a new customer that added an additional environmental concern for using the sensors. Standex Detect then revised the cable within the custom sensor to be plenum rated to meet the environmental requirements of their new customer.