There's a mistake on 4:43. The strain gauge resistance must be 20 ohm, just like R3, for a bridge to be balanced. Also on 5:30, the more temperature you apply, the more resistance increases. So, for example, it must increase to 22 ohms. But you're showing that it decreases. Otherwise very good, clear explanation! Thank you, dude!
disagree. Seems like an important reason for why this configuration is used is to account for resistors and systems not being ideal.. Although 20 ohms may make the bridge balanced in ideal conditions, this is real life. 23 ohms might be needed to balance the circuit due to the resistors not being ideal and environmental factors such as temperature
@@clobraico_private9121 that would have been plausible if he had explained that pragmatic scenario. The explanation should stick to the theory. If you dont understand the theory you wont understand its real world effects and variations.
Resistors come in large variation of properties and not all respond the same way to changes in temperature. Look up thermistors; they come with negative (i.e. temp goes up resistance goes down) and positive (vice versa) temperature coefficients. Now: Even resistors that aren't purpose built to respond to temperature coefficient. And whether the temperature coefficient of any given resitor is positive or negative depends on its construction and the materials its made from. Therefore the generalization "the more temperature you apply, the more resistance increases" is incorrect.
good explanation, but you should mention that the big advantage of the wheatstone bridge is that the voltmeter actually shows the small deviation from the equilibrium and thus you can use a much more sensitive measurement range. In your example of 20 ohm resistors (quite low value by the way) if you would only measure one resistor which changes from e.g. 20 ohm to 20.2 ohm than this would only be a change of 1% seen on the last decimal on a regular multimeter. Even if you just measure the voltage on the right side, you end up with an unuseable value of just 5.02 V, also here the important information is hidden in the last digit of the multimeter. However, if you measure the difference between the two voltages, you get a value of 25 mV which you even might be able to read with an addition decimal in the millivolt range of your multimeter.
I was just looking for something like this but didn’t know it could be made this simple! I need to use a thermocouple to read temperature with a arduino but the resistance change over the thermocouple is too small to be noticed. Thanks and great timing :)
Thank you for saving my life with this video. Those fucking physics teachers in my country just taught me to check the ratio between the resistances of resistors without any explanations.
The main goal of this video is how to eliminate temperature effects from our sensors. No one of the professors on our faculty could explained like that.
Your videos are so SO good and well explained! I love your style of explanation where you sandwich the theory in between practical usage and that makes it really easy to follow and understand. Thanks for making these videos!
Nice explanation, but using quarter wheatstone bridge as u showed in this video doesn't solve the problem with temperature messing up the measurement, because it's very likely that resistors used in this bridge will have different temperature coefficient than the strain gauge. We should use the half bridge instead, so 2 strain gauges , to make sure that the changing temperature won't mess up our mesurements, am I right?
simple explanation with out all the math seems to be, you adjust the variable resistance to balance the voltage bridge to equal 0. Because its 0, you can use the variable resistor to find out what the unknown resistor is. and you do this to get a more accurate reading. and that's it. its only advantage is a more accurate reading then just using another meter.
I don't know if the same thing happens in the US, but in Brazil everyone sees this and many other advanced subjects in high school, you just need to search "ponte de whatstone" here and you will see the number of video lessons, it's crazy
The explaination is correct but to apply the voltage divider metod you must first asume that the voltage between c and d is 0V, and not the other way around
but R1, R2 and R3 are not effected by the same temperature that was given to the Thermistor, so they are not all effected at the same time like you said in the minute before. how can you explain this ?
Hey what about using just a simple voltage divider - just put the strain guage in series with another known resistor, and measure the difference in the voltage drop...? Is there any advantage over the wheatsone bridge?
@3.51 sec, you say , R3 can be changed until Vc = Vd; but didnot understand here.. Rx is a R3*const(Ratio of other two resistors). How can you change only R3 to make Vc = Vd. This part is not clear. Once we know R1, R2; Rx is R3* Ratio of (R1 & R2) assuming Vc = Vd. In this case i can choose R3 any value of Ohms and it will meet the criteria. so why do we need to change R3 value
Hello ! I liked your method of explaining you do a very good job but i have a small question how a voltage divider will existe if we have spplited current i think if we you ohm lows would be more satisfying and thanks you
Just looking into the wheatstone bridge with a thermistor for one of my projects. Have you used this with the Arduino for temp readings? Currently I'm just using the thermistor in a voltage divider and it's quite accurate but can never have high enough accuracy right? :) if you haven't done said project, any chance?
In my school we did it with a two resistor voltage divider. Why do i have to use a Wheatstone bridge compared to a simple two resistor voltage divider?
Hi bro very good idea but how we can attach this to microcontroller using list means I would ask otherwise the project is awesome house have a good idea for project why not to make a constant current source for example in LED driver or something else Goodluck
actually the device should be called Christie's bridge after Samuel Christies the actual inventor... wheatstone only popularised it in his days and some one else named it wheatstones bridge because back then the real inventor wasnt realy known and wheatstone was an already famous person...so the wrong person gets the credits (again)
*PLZ HELP*. Given a pressure of 2kpa, nominal resistance of 120 ohm, diameter of strain gauge 0.1mm, a GF of 2. What will be the change in resistance value of the strain gauge?....in short I wanta formula to calculate the change in resistance of strain gauge for a given INPUT PRESSURE
