Recent content by Voltux

1. B How to set up an integral to integrate over a sine wave?

How do I setup an integral to integrate over the following equation: V(t) = 1/(R*C) integral to t Vin(t) dt This is the capacitor voltage over time formula. I want to integrate over a sine wave from 9 to 81 degrees. Frequency of 120Hz, amplitude of 120V. The formula I used in wolframalpha is...
2. B How to distribute a fraction?

Svein, I would like to say thank you so very much for pointing this out to me. I believe you truly made my evening. I indeed performed the calculations and get -468/-52 = 9. Can you cite the rule or fundamental misunderstanding that I have missed? I was under the impression that we can...
3. B How to distribute a fraction?

I'm given the problem 14x+5y=31, 2x-3y=-29 This is a set of linear equations that I am asked to solve. That being said I am getting hung up on how to distribute a fraction. The answer is x=9, however, I am getting x=36 and the step I do not understand is distributing the fraction. We then get...
4. Calculating Free Body Diagram Forces

Okay, this makes perfect sense now. So in very simple terms the middle joint has forces that cancel out, hence the Fy in opposite directions because it does not move. It is supporting forces in both directions and therefore must sum to 0 net force. Thank you!
5. Calculating Free Body Diagram Forces

On EngineersEdge.com they have a free body diagram of a scissor lift https://www.engineersedge.com/mechanics_machines/scissor-lift.htm Can anyone explain how the Fy, Fx components are determined? What is specifically confusing to me is how Fy is opposite in direction given the system. To me...
6. What's the advantage of using a voltage buffer amplifier?

A voltage follower is used to buffer the signal. It is helpful for changing impedance, too. For example if you have a high impedance source that you cannot load, maybe a crystal oscillator, you can use the voltage follower to then distribute the signal to multiple loads, or maybe an amplifier...
7. MeOH:H2O Freezing Point Depression Calculation Issue

I noticed that my windshield washer fluid has methanol in it to reduce the temperature of which it freezes. I know it freezes at approximately -28°C which gives us a concentration of MeOH at approximately ~30% by weight. However, when I try to calculate the required methanol using the mSolute...
8. Looking for info on balancing and counterbalancing design.

I wasn't quite sure which section to post this in but engineering was the closest to my application, although this could be a basic physics question. I'm not sure. I want to learn how to design a counterbalance such as that in an engine crankshaft. This mechanism has been of interest to me...
9. Can someone explain this complex math problem?

I'm working out an impedance matching problem from a textbook (it is not part of any coursework) and I am trying to figure out how they get the 315 term in the polar coordinates below. Z = (XC*RL)/(XC+RL) = (-j333*(1000))/(-j333+1000) = 315 , -71.58* = 100 -j300 ohms I calculated that...
10. I What is the approximate impedance of an RF plasma "antenna"?

From my understanding the excitation of plasma has different mechanisms for DC breakdown vs RF. I believe the RF is a means of magnetic excitation whereas the DC breaks off an electron or something like that. I can't remember off the top of my head. I have done the DC method and I believe I...
11. I What is the approximate impedance of an RF plasma "antenna"?

I've searched high and low for data regarding this from scientific papers to books and I cannot find anything in regards to the approximate impedance to excite a vacuum vessel to plasma state. In particular I want to built a RF Plasma cleaning chamber, however, I am not sure how to design the...
12. How do I get a DC difference amplifier working?

I have answered my own question after further research. Removing the resistors gives an ideal op amp infinite voltage gain operating "Open Loop". The LM358 for example has approximately 100dB of gain which is 10^5*(V2-V1) since the op-amp responds only to the difference signal (V2-V1) where V2...
13. How do I get a DC difference amplifier working?

I've been trying to figure out why my DC subtraction amplifier is not working, and am completely baffled. I have set up an op amp with no feedback resistors with voltages applied to both the inverting and non-inverting inputs as specified below. I previously had the op amp setup with a 10x gain...
14. Calculating required amount of molecular sieves for PSA?

Does anyone know how to properly calculate the amount of molecular sieves needed for a pressure swing adsorption system? I have searched application notes, books, and of course google, and while I find the basics of how they are constructed I cannot find any information on the quantity...
15. Calcium Carbonate -> Calcium Oxide, but only getting Hydroxide. Ideas?

I was testing with vinegar to verify a change had taken place, and that it was heated long enough. This would only show that I did not have a carbonate. I suppose you're right that both CaO, and Ca(OH)2 would form a milky white mixture, but when I added the powder to water (just enough water...