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  • SillyInventor commented on SillyInventor's instructable How to Make a DIY Force Plate5 months ago
    How to Make a DIY Force Plate

    If you only need a sum, use an op amp set up as a mixer. Instructions are available online.If you want individual values or you need 16 bits you can use the ADS1115.You may be limited by the read speed of the arduino. I've not used a teensy with the relevant library.The question is how accurate does your system need to be, and how good are your load cells. 24-bits is on the order of 10 ppb. IE if you're reading 0-10lbs, and have perfectly setup your range, that's 0.000001lbs resolution, can your load cells provide that level of accuracy? Can your setup? How accurate do you need to be? Without knowing the application, I can't answer that for you.If you do a mixing op amp, it can take any number of load cells. If you can have multiple ADS1115s in a row, still any number. If you can have o...

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    If you only need a sum, use an op amp set up as a mixer. Instructions are available online.If you want individual values or you need 16 bits you can use the ADS1115.You may be limited by the read speed of the arduino. I've not used a teensy with the relevant library.The question is how accurate does your system need to be, and how good are your load cells. 24-bits is on the order of 10 ppb. IE if you're reading 0-10lbs, and have perfectly setup your range, that's 0.000001lbs resolution, can your load cells provide that level of accuracy? Can your setup? How accurate do you need to be? Without knowing the application, I can't answer that for you.If you do a mixing op amp, it can take any number of load cells. If you can have multiple ADS1115s in a row, still any number. If you can have only 1 ADS1115 it's limited to 4.Microprocessors are application specific. Does it need to be low power? Collect other data? Be reconfigured etc.The Teensy needs header pins and a breadboard. If you're getting the ADS1115, I recommend getting it on the adafruit breakout board, it's just easier and about the same price. If this is your first electronic build, I strongly recommend making a circuit diagram and ensuring you have all the components first. I am not sure what load cells you're using, but they may ore may not require resistors, amps, etc.That's.... a long question. It gets into the depths of sensor design. If you have time, read Practical Electronics for Inventors. If not, read: https://learn.sparkfun.com/tutorials/getting-started-with-load-cells

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  • SillyInventor commented on SillyInventor's instructable How to Make a DIY Force Plate1 year ago
    How to Make a DIY Force Plate

    1, Fz. However, to clarify, Mz is just standing Fz/g.

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  • SillyInventor commented on SillyInventor's instructable How To Make a DIY Force Plate1 year ago
    How To Make a DIY Force Plate

    None of the components should experience high current, so 0.25w will be more than enough for any of the resistors. The opamps are similarly open ended with few requirements by design (we wanted it to be easy for the students to get into).The only consideration is that, if you intend to amplify something by this amount, you must be relatively certain of the voltage divider resistance. So good tolerance (1%) and little change with temperature is ideal for the 330 ohm resistor.

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  • SillyInventor commented on SillyInventor's instructable How To Make a DIY Force Plate1 year ago
    How To Make a DIY Force Plate

    Yes. To globals also add:int redLED= 1;int greenLED= 1;And to the loop add after the rest:else { digitalWrite(redLED, HIGH); digitalWrite(redLED, LOW);}Then into the two prior conditionals add: digitalWrite(redLED, LOW); digitalWrite(redLED, HIGH);

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  • SillyInventor commented on SillyInventor's instructable How To Make a DIY Force Plate1 year ago
    How To Make a DIY Force Plate

    Certainly, this is the sort of thing I do with students, and which is a simple introduction as it requires only the smallest amount of code to write a program to return that. Add globals:const int threshold = 255;int startContactTime = -1;Then add in loop:if( startContactTime== -1 && analogRead(0)>threshold) //check to see if pressure has been applied for the first time startContactTime=Millis(); // if it is, capture the time (millis will return the time in millisecondselse if (startContactTime!= -1 ) //if the plate was contacted, but isn't anymore{ Serial.println(Millis() - startContactTime); //display the time at release startContactTime= -1; // clear the time for contact}When I run classrooms, I prefer instruments that are versatile enough so that students can bra...

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    Certainly, this is the sort of thing I do with students, and which is a simple introduction as it requires only the smallest amount of code to write a program to return that. Add globals:const int threshold = 255;int startContactTime = -1;Then add in loop:if( startContactTime== -1 && analogRead(0)>threshold) //check to see if pressure has been applied for the first time startContactTime=Millis(); // if it is, capture the time (millis will return the time in millisecondselse if (startContactTime!= -1 ) //if the plate was contacted, but isn't anymore{ Serial.println(Millis() - startContactTime); //display the time at release startContactTime= -1; // clear the time for contact}When I run classrooms, I prefer instruments that are versatile enough so that students can branch off and make different things. However, when running a workshop with this project, I found that there wasn't enough time to properly teach the students the analog components in this lesson. If you know that no force data is required, I suggest using another sensor like:https://www.sparkfun.com/products/8685to cut back on the number of analog components the students need to understand. It makes it faster and easier, and there is plenty of room to branch out.

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