![]() Hall Effect SwitchesĪs mentioned above, Hall Effect switches respond to magnetism.ĭon’t confuse these with magnetic reed switches. ![]() If you wish you can use the same code for other types of switches as well. Today we are going to build our homing sensor and limit switches using Hall Effect switches. They can, however, be falsely triggered by stray magnetic fields if not mounted properly. They don’t experience wear and tear and are not affected by light or heat (within reason). Hall Effect switches: These devices respond to magnetic fields, so they can be triggered by a small magnet.They don’t experience wear and tear and can work in many environments, providing their light source is not obscured. Either reflecting or breaking an infrared light beam will trigger the switch. Optical Switches: Usually these are either the reflective type or the “optical source-sensor” type with a gap in them.They are also not suitable for some environments where they would be subject to dirt, oil or moisture. They work well, but as they are mechanical they can wear out. Microswitches are commonly used in this application. Conventional (mechanical) switches: These are easy to work with and are available in a wide variety of styles.You can use many kinds of switches to build homing sensors and limit switches. Many printers go through a sequence of operations when they are powered up, and one of them is to move the print carriage to the homing position to get a reference point. From there you can use the precision of the stepper motor to accurately move into any position you wish.Ī common use of the homing sensor that you are probably familiar with is in a printer. Once it is activated the motor “knows” where it is. Once the switch is activated the motor will respond, how it responds is entirely up to you, but in most cases, it will either stop or reverse.Ī Homing Sensor or switch is placed in a predetermined position to provide a reference point. Limit Switches are generally used in pairs and are placed at the mechanisms the end of travel. Limit switches and homing sensors are ways of determining the position of either the stepper motor shaft itself or of the mechanism that the shaft is powering.īoth schemes use switches of some sort that are activated when the shaft or mechanism reaches a certain position. We’ll take a look at a couple of methods today. In some cases, you really don’t care what the current shaft position is, but you do want to know when the stepper (or the mechanical devices being driven by the stepper) has reached a certain point in its travel so you can stop or reverse the motor.įortunately, there are a couple of ways to resolve these issues. So when your stepper-based project is first powered up it really has no idea what position the motor shaft is currently sitting at. This is why stepper motors find use in application like printers and DVD drives, they are a great choice anytime a powerful yet precise motor is required.īut, unlike servo motors, stepper motors do not normally have an internal feedback mechanism to determine the current shaft position. Stepper motors allow precise control of their shaft position, using microstepping you can control this to a fraction of a degree. We have used stepper motors in many of our projects and experiments, and for good reason.
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