Strip down an old mouse - they have slotted sensors in the majority of them and can be picked up for pence (cents) Dom ----- Original Message ----- From: "Pang" To: Sent: Sunday, August 11, 2002 9:25 PM Subject: Re: [EE]: What is the estimated torque ? > Hi, > > Is a slotted disc sensor available as one unit? Can you suggest one? Or are > you just suggesting that I can built a tilt sensor out of a slotted disc > with a pair of optical sensors? > > Quite a number of piclisters has suggested to built something similar to the > mouse mechanism, but I think, eventhough it is workable it may not be that > practical as a product. Nevertheless, will get an old mouse and try to built > one. :) > > Thanks > > Rgds, > pang > > ----- Original Message ----- > From: "M. Adam Davis" > To: > Sent: Friday, August 09, 2002 10:27 PM > Subject: Re: [EE]: What is the estimated torque ? > > > > I would suggest the a pot is not the way to go then. When the car is > > accelerating and stopping the weight is going to swing. The pot is > > going to wear out very quickly. > > > > As a proof of concept it is a good idea, but ultimately you'll want to > > replace it with something which suffers less wear. > > > > If you just want to measure tilt, use a slotted disc sensor with a > > weight (easy o build). When the car gets turned off the microcontroller > > should save the current setting (in a slot or out). If the car is > > tilted then the weight will change the setting. > > > > The nice thing about this is you don't have to remember analog voltages, > > or even deal with what happens when you park the car on a hill. > > > > -Adam > > > > Pang wrote: > > > > >Hi, > > > > > >Thanks for suggestions and questions. It shows I have not been thinking > > >thoroughly on the method of implementation. First of all, the application > I > > >will be building is going to be a tilt sensor. If you still recall, > there's > > >a few thread on this subject not too long ago and someone actually > suggested > > >using a potentiometer to measure the tilting by attaching a certain > amount > > >of weight to the shaft. I think the name 'tilt sensor' is misleading. > > >Tilting here is not a 180 deg upside-down turn. It is meant to be > installed > > >in an automotive to detect towing. As such, I think an angle sensor will > be > > >a more appropriate name. > > > > > >Thanks for highlighting the different aspect of torque calculation. What > I > > >intend to do is to attach a weighting to the shaft. The potentiometer is > > >fixed to a flat board. Whenever the board is raised at either side, the > > >weighting will move the shaft. The weight that is atttached to the shaft > > >must be concentrated to a certain direction only, something like a > pendulum. > > >Or let say the weighting is in the form of an arrow. The shaft will be > > >attached to the beginning of the arrow while the arrow will always point > to > > >the gravity, assuming the end of the arrow is heavier than the beginning. > > > > > >phew.... i hope you guys understand my kindergarden level of > description... > > > > > >I have enquire things like rotary encoder, position sensor, optical > sensor > > >and angle sensor. But most of them are either costly or that they cannot > > >withstand much load to the shaft. It seems that the life of the ball > bearing > > >will be greatly reduced. I am quite limited in my mechanical knowledge, > > >otherwise there are lot's of method of doing it. > > > > > > > > > > > >>What will be turning the pot? The weighting attached to the > shaft > > >> > > >> > > > > > > > > > > > >>Will it turn the pot directly, or is there a > > >>knob/attachment/lever/belt/pulley/etc on the pot? > > >> > > >> > > > > > >The weighting will turn the pot directly ( that's the easiest method i > could > > >think of ) > > > > > > > > > > > >>How much force is going to be applied to the point at which they (the > > >>pot and the other object) meet? > > >> > > >> > > > > > >? > > > > > > > > > > > >>Are you also going to be dealing with friction/slipping? > > >> > > >> > > >> > > >I was thinking that the weighting will be attached permanently to the > shaft, > > >the weighting will not slip but the shaft will be turn according to > gravity. > > > > > >I have been searching for quite some time for a cheap solution (USD5 for > the > > >potentiometer) but it seems not possible. The only way is still using the > > >accelerometer. > > > > > >Thanks for the explanation of the fan, the torque and the different force > > >required. > > > > > >Best rgds, > > >Pang > > > > > >----- Original Message ----- > > >From: "M. Adam Davis" > > >To: > > >Sent: Tuesday, August 06, 2002 10:59 PM > > >Subject: Re: What is the estimated torque ? > > > > > > > > > > > > > > >>Your questions don't add up. > > >> > > >>I can turn a high torque anything with my finger if the knob is big and > > >>light enough. In other words, the force you apply with your finger > > >>translates to torque through a lever. If you have a small diameter > > >>shaft on your low torque pot, then your finger may have to apply a great > > >>deal of force to turn it, if you attach a 1 foot stick to it then your > > >>finger will have to apply very little force to the end of the stick. > > >> > > >>The fan blade is the same way. You'll apply less force at the ends of > > >>the blades then you'll apply at or near the center. > > >> > > >>The trade off is distance moved. At the center you only need to move it > > >>a little to get a large degree of rotation, whereas at the outside you > > >>need to move it further. Force * Distance = Work, the work is the same > > >>whether you turn it a the center or the end, but the distance and force > > >>changes. > > >> > > >>If you knew the torque you needed (ie, .01 foot pound or some other > > >>absolute torque measurement) then we could help you more easily. > > >> > > >>Since, however, you seem to be asking for a relative measurement (fans > > >>have widely varying torques) then you need to give a little more > > >>information: > > >> > > >>What will be turning the pot? > > >>Will it turn the pot directly, or is there a > > >>knob/attachment/lever/belt/pulley/etc on the pot? > > >>How much force is going to be applied to the point at which they (the > > >>pot and the other object) meet? > > >>Are you also going to be dealing with friction/slipping? > > >> > > >>By the way, a normal desktop fan requires a lot more torque to turn than > > >>any small pot I've ever dealt with. Take the fan blades off the shaft > > >>for a better torqure comparison. Better yet, put the fan blades on the > > >> > > >> > > >pot. > > > > > > > > >>I hope this helps! > > >> > > >>-Adam > > >> > > >>Pang wrote: > > >> > > >> > > >> > > >>>Hi all, > > >>> > > >>>Just received a sample for a low torque potentiometer. As i checked it, > I > > >>>found that it is not suitable for my application. The torque is not low > > >>>enough eventhough the potentiometer is classified as low torque. As > such > > >>> > > >>> > > >I > > > > > > > > >>>would like to enquire, what is the estimated torque such that I can > turn > > >>> > > >>> > > >the > > > > > > > > >>>shaft of a potentiometer using only one finger? Or maybe in another > > >>> > > >>> > > >way... > > > > > > > > >>>what is the torque for a normal desktop fan? Is such a potentiometer > > >>> > > >>> > > >(with > > > > > > > > >>>that level of torque) available? > > >>> > > >>>Thanks.. > > >>> > > >>>Best rgds, > > >>>Pang > > >>> > > >>>-- > > >>>http://www.piclist.com hint: The list server can filter out subtopics > > >>>(like ads or off topics) for you. See http://www.piclist.com/#topics > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>-- > > >>http://www.piclist.com hint: The list server can filter out subtopics > > >>(like ads or off topics) for you. See http://www.piclist.com/#topics > > >> > > >> > > >> > > >> > > > > > >-- > > >http://www.piclist.com hint: The list server can filter out subtopics > > >(like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > > > > > > > > > > > > > > > > > > -- > > http://www.piclist.com hint: To leave the PICList > > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.