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