Alternatives to Hall Effect Sensor - Page 1
Forum section: electronics / beginners

author: geratheg
author_rank: Regular Contributor
timestamp: May 06, 2015, 12:38:20 am
content: I have a motor that uses a speed controller knob. I opened the box where the knob is and looked at the wiring and it appeared very fragile. The wires had broken. The engineering was not good. I'm not sure what controlled the speed, but the knob was magnetic and had a transistor looking thing. I think it uses a hall effect sensor?There is a revolving magnet and turning the knob variably adjusted the motor's speed.I need to replace the sensor because the pins completely broke off. I need this in 3 days and could order replacements, but I'm not sure if they will arrive on time. Are there alternatives to hall effect sensors? Does it matter which hall effect sensor is used as a replacement?I looked at it, and it was kind of difficult to read but showed: 41905d on the component that I'm holding.I just can't find many local electronics shops here.I'm using the motor from electricpaddle.com

author: geratheg
author_rank: Regular Contributor
timestamp: May 06, 2015, 03:12:13 am
content: I figured out there is an electronics shop in my area which has hall effect sensors.My new problem is this: Which one do I need? Here is their website:http://www.newark.com/webapp/wcs/stores/servlet/Search?catalogId=15003&langId=-1&storeId=10194&categoryId=800000004621&st=hall%20effect&pageSize=25&showResults=trueAnother question: Can a potentiometer be used in place of a hall effect sensor? Wire the ends of the potentiometer to power and gnd, and use the middle as the variable voltage pin. Will that work?

author: Jonny
author_rank: Regular Contributor
timestamp: May 08, 2015, 09:57:08 am
content: I think there's more going on here. A speed control knob with a hall effect sensor on it will only register in one position as it won't be constantly turning. I'd expect a hall effect to be against the motor shaft which would contain a magnet so the control circuit can count pulses to maintain speed. That being the case just putting a pot in there won't work with the existing control system. Really need more info on the design to help with a fix I think otherwise just bang any sensor in there and see what happens. Read the datasheet to figure out which wire goes where.

author: mikerj
author_rank: Super Contributor
timestamp: May 08, 2015, 10:58:47 am
content: Quote from: Jonny on May 08, 2015, 09:57:08 amThat's what I thought the first time I read this, but it's entirely possible to have an analog control system using a hall effect sensor. Hall sensors are inherently analog devices after all, though many include a comparator to give a digital output. Turning the knob would move the magnet and vary the field strength across the hall sensor, giving a variable output voltage. This would mean all the electronics could be completely encapsulated and waterproofed, with no need for shaft seals etc.If this is how it's used, then a potentiometer is quite likely to work as a (much less waterproof) replacement.

author: BradC
author_rank: Super Contributor
timestamp: May 08, 2015, 11:04:12 am
content: Quote from: mikerj on May 08, 2015, 10:58:47 amThis is how the joysticks in electric wheelchairs work. No mechanical wiper to wear out. Personally I *love* the concept.

author: Jonny
author_rank: Regular Contributor
timestamp: May 08, 2015, 11:06:02 am
content: Thanks for clarifying that

author: geratheg
author_rank: Regular Contributor
timestamp: May 08, 2015, 03:38:06 pm
content: I gave the company a call and they told me that a linear net centered Hall effect sensor will work as a replacement or a pot.Thanks for all the help.