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  1. R

    Can someone send me a link for a good 36v SLA battery charger?

    You have to read the specs of all those 36 volt re-energizers. Also don't try to re-energize more that one 36 volt battery at a time. In other words, don't gang re-charge them. Ratch
  2. R

    Can someone send me a link for a good 36v SLA battery charger?

    I Googled "36 volt sla battery charger" and got zillions of hits. Why could you not do the same? Ratch
  3. R

    Not transistor and weak electromagnet

    Twelve volts and two volts equals fourteen volts., How can that be? Scope the base and collector leads to the transistor and see if there is an oscillation present. That solenoid provides plenty of inductance and the capacity of the leads could support an oscillation. Especially if the leads...
  4. R

    Transistor Help

    You really need to know the voltage to trigger the solenoid and the resistance of the coil. In other words, you need to know the parameters of the load. If the trigger voltaqe is 5 volts or less, then I would put the coil in the emitter circuit in a common collector configuration. Hopefully...
  5. R

    Energy Lost Due To Friction

    To be complete, the next question after whether is why. I believe both of our answers are equally intuitive, but mine is easier to determine. Ratch
  6. R

    Energy Lost Due To Friction

    Why do you think it is not intuitive? Does it not make sense to realize that the longer the trolley takes to descend he incline, the more friction resistance is present? The simple concept of friction slowing the descent is in play for this problem. Ratch
  7. R

    Positively charged "holes"?

    It heartens me to observe that even though you lack understanding of some of the quantum physics basics, at least you know and acknowledge your lack. I have had arguments with folks who were clueless, but thought they knew what they were blathering about. Holes and electrons are a simplified...
  8. R

    Energy Lost Due To Friction

    As was mine also. In my method, the angle is needed, the friction is not. The angle is readily available, the friction is not. No need to measure the any velocity with my method. Time of descent is all that needs to be measured by my method. Good question. Why get involved with measuring...
  9. R

    Energy Lost Due To Friction

    Both the Duke's method and my method use the same concept, specifically, that energy is lost by friction. The difference is in the way the loss is determined. I don't think there is any doubt that my method is easier to implement because only the time needs to be measured, instead of before...
  10. R

    Energy Lost Due To Friction

    Show us the method and approach. Inquiring minds would like to know. Ratch
  11. R

    Energy Lost Due To Friction

    Did I not aver in the post before yours, that knowing the potential energy, kinetic energy, and velocity are not necessary to calculate the energy lost due to friction? Before you say otherwise, you should read my post and prove me wrong first. Only the time of descent needs to be measured...
  12. R

    Energy Lost Due To Friction

    To the Ineffable All, I looked at the problem again, and this time I determined that it is a trivial exercise in kinematics. No need to know the starting potential energy, coefficient of friction, final velocity, height above the ground, etc. All that is superfluous information that gets in...
  13. R

    Convert waveform formula to 'usual' cos sin formula to sketch graph

    True, it is a clunky, clumsy way to present a simple trig equation. But, I was trying to show him how to find the frequency and period of the second equation involving the 650 times "t" term. I let him figure out how to simplify the phase change term of 10. Ratch
  14. R

    Phasors and Phase angles

    You have got to know whether the circuit is series or parallel. In a series circuit, the current is the same to/from each component, so the voltage is referenced to the current. In a parallel circuit, the voltage across each component is the same, so the current is referenced to the voltage...
  15. R

    Convert waveform formula to 'usual' cos sin formula to sketch graph

    I don't see what the problem is. Simply convert the coefficient 650 into a frequency as shown below. Below is plot of the original equation. And, it matches with the revised equation. Ask if you have any questions. Ratch
  16. R

    Charge a 36V Battery in Series

    Return that Li-on energtizer. Purchase an energizer specifically made for the particular sealed lead acid (SLA) battery you have. Google for SLA batteries, and you will receive more hits than you can read in your lifetime. Ratch
  17. R

    RLC series question

    Yes, it is wrong. I don't know where that formula you posted comes from. But, for an ideal coil, cap, or resistor in parallel, the equation I gave you is correct. Now, if the coil or capacitor contained some resistance, the formula would be different. You can find the resonant frequency by...
  18. R

    RLC series question

    Resonance occurs when the inductive reactance equals the capacitve reactance.Therefore: Plug in the values for L and C to get a resonant frequency of 23.73 Hz. Notice that R has nothing to do with the resonant frequency for this circuit. Now, if you inserted some R in series with L or C, that...
  19. R

    RLC series question

    You need to show the derivation of the resonance formula. Up to now, all you posted is a bunch of numbers.. Ratch
  20. R

    RLC series question

    Well, your calculations were correct, so either you don't know how to run Falstad, or it has a bug in it. Now, how about getting the formula for resonance squared away. Ratch
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