Search results

  1. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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. V

    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...
  16. V

    Calcium Carbonate -> Calcium Oxide, but only getting Hydroxide. Ideas?

    I was trying to calcine some CaCO3 (Calcium Carbonate), but ended up with Calcium Hydroxide. To test if I had Calcium Carbonate I added it to some vinegar, no gas was produced. I then mixed in a small amount of the powder with a large amount of water and passed CO2 through it, and it became a...
  17. V

    Calculating Insulation Thickness

    I'm trying to calculate insulation thickness for a foundry, and can't figure it out after spending a few hours searching. Refractory: Kast-O-Lite Material Required: 1.44g/cm^3 Thermal Conductivity: 0.65 W/m*C Maximum inside temperature is 1648*C I figured there would be a minimum of...
  18. V

    Amount of Propane Required to Melt 1L Aluminum

    I started off yesterday learning about specific heats, and measuring my ice cubes to figure out the correct number to cool my tea to a proper drinking temperature. Now today I was curious how much propane would be required to melt 1L of Aluminum since I'm also interested in casting Aluminum...
  19. V

    Confused with Rate Problems/Coefficient, Pos/Neg signs.

    How do I determine if I subtract or add the coefficient to the fraction? ex. 1-(-48/18)*Sh=384 vs 1+(-48/18)*Sh=384? Also, It would be the Sh+Sm=312 where I get the coefficient "from" right, specifically the second "Sh" term where as the sm term is eliminated with -sm. Thanks! (The...
  20. V

    AM Demodulator: SSB -> AM; Op Amp?

    Thanks! Consider my question solved. I'm following Scott Harden's plans for the SA612 and reading through the 2011 ARRL Handbook for Radio Communications as well. Just trying to get a block view I suppose of how a SSB Receiver would work as opposed to an AM. http://www.swharden.com/blog/ -...
  21. V

    AM Demodulator: SSB -> AM; Op Amp?

    Greetings Physics Forums, I'm reading up on Radio Circuits and studying for my General's Amateur Radio License and was learning about AM Demodulators. I understand that in AM you can use a peak detector to get the modulated audio out however in SSB radio don't you have to double the...
  22. V

    Relay causes circuit interference?

    Hey Belias, I have to agree with schip666! here, your relay could be drawing too much current. If your circuits are getting damaged or quit working it could also be Back-EMF from your relay which can be solved with a simple diode. You could also use a Solid State relay or even a MOSFET in...
  23. V

    18V Batt. to 5V USB Port and 12V CIgarette Lighter

    Hey Brandon, Glad to see you have an interest in EE, Cars are especially tough to work with they can fry your electronics if not done properly such as when you start the car with sensitive electronics plugged in all sorts of voltage spikes and such. There are really two main power...
  24. V

    Assorted Resistor and Capacitor

    Hey Prescott2006, There aren't just a few values used however there are standards of values such as E12/E24. You may find this helpful in deciding what components to purchase. Also, 50 caps and resistors are not bulk, when you talk 50,000 that is bulk. Perhaps you would be interested in some...
  25. V

    Calculators HP50G, Number solver menu no longer shows

    Hey PhysicsForum, When I press Right Shift + 7 (NUM.SLV) For solving linear equations i usually get the menu but now it shows a different menu instead of the popup menu it now shows Root Diffe Poly Sys and Tvm over the F keys. Can anyone enlighten me as to how to get my menu back? Thanks...
  26. V

    Driving 15 LCD Possible?

    Thanks for the reply, That answered my question. I have some dead laptops and I hate to throw them out because most of the components are still good. Lucky for me though the PDA screen is from Sony and has a data sheet. Sincerely, Voltux.
  27. V

    Driving 15 LCD Possible?

    Driving 15" LCD Possible? Hey Physics Forum, I have some large LCD's such as those out of laptops and I was wondering if they can be turned into a monitor for a computer or something such as a project screen. I'm not so much looking for a step-by-step or any instructions because I'm not that...
Top