Designing Sensors

I have been designing reed switches and proximity sensors to meet the needs of the multitude of applications that are out there for 40 years.  The primary purpose of our sensors is to convert a mechanical motion to an electrical signal.  The designs of these sensors can be very simple or really critical and complicated.

The following bullets are intended to assist in considering the elements of your application and reaching an ultimate solution easier and faster.

Identify the parameters of your application

1. What is moving, what material is it made of?
2. How far and how fast does it move?
3. What type of signal do you need? Volts______ AC / DC,  amps ______, watts _______

Determine The electrical signal

1. Normally open, meaning the circuit is open until the target is present and signal is generated.
2. Normally closed, meaning the circuit is closed, signal is present and then the signal is lost when the target is present.
3. SPDT, single pole double throw, having both normally open and normally closed signals in the same sensor (3 wires: common, normally open and normally closed)
4. Sensor assemblies can be built with redundant signals, two of the same outputs inside one sensor assembly. Both signals respond to one target approach and withdrawal.

What are the environmental issues involved

1. Temperature range: +_____________  –  _______________
2. Shock: Yes/No  __________    G level ______________
3. Vibration: Yes/No __________     Frequency & Force _____________
4. Chemical and gas exposure: _______________________________________
5. Sound and noise interference: _____________________________________
6. Other: ________________________________________________________

additional design considerations

1. More environmental areas of concern are other devices near the sensor. Components that could generate or affect a magnetic field (motors, nuts, bolts, capacitors, batteries, brackets, other ferrous components) can affect sensor operation.
2. What would you like the device to look like? Color, shape, wire type – color and length, armored cable, connector, identity (part number) on the part.
3. Is device traceability to raw materials required, is date code important
4. Estimated annual usage. Knowing the potential quantities helps determine manufacturing costs.
5. Can a stock housing (or slight modification thereof) be used instead of a custom sensor size & shape. This will save significant cost in development.

Thinking through these few questions saves significant time and helps cover all the aspects of a sensor application.  It is intended to help select the best sensor and prevent overlooking any parameters that can affect performance.   Feel free to download this list and ‘fill in the blanks’. We have a dedicated Design Engineering Team on staff ready to take your answers and turn them into a solution.