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  1. BobK

    Voltage: a force or a form of energy

    Ramit, I say a voltage is not a force, and you say you still think it is a force. As, they say, you are entitled to your own opinion, but not to your own facts. Let me give you an analogy; Is the height of a dam a force? When you say you think voltage is a force, you are basically...
  2. BobK

    Heating Element?

    You both realize that what he is trying to do is vaporize the THC in some weed, right? My last response on this thread was deleted and this one probably will be as well. Bob
  3. BobK

    diode for collapsing magnetic field

    CDIRVE, I really don't see what you are getting at. If the back EMF dominates when you remove power from the motor, the diode would do nothing since it would be reverse biased. Are you suggesting that the diode should be the other way around? Bob
  4. BobK

    Voltage: a force or a form of energy

    Forces are measured in Newtons. How many Newtons is 10 Volts? Bob
  5. BobK

    Voltage: a force or a form of energy

    Voltage is neither a force nor an energy. If it were, it could be measured in newtons or pounds (force) or in joules, or foot-pounds (energy). It is a potential difference. A potential is a scalar quantity than can be defined at any point in an electric field. You need to add charge to...
  6. BobK

    diode for collapsing magnetic field

    Presumably there are both effects going on, but it is the collapsing field that kills electronics, it can create an extremely high voltage, enough to arc across the relay contacts in this case. Bob
  7. BobK

    Capacitors What to pick?

    Most of those types do not come in 1000s of uF, which is what you are going to need. Typically, electrolytics are used. Bob
  8. BobK

    H-bridge with 4 N-ch FETs

    You need a high-side driver. They use a bootstrap capacitor to raise the voltage above V+ in order to turn on the gate even though the source is at a high voltage. The are often packaged as a high and low in one package to drive half a bridge. There might even be full bridge drivers. Bob
  9. BobK

    diode for collapsing magnetic field

    V = L dI/dt The voltage across the inductor is related to the rate of change of the current. So it is opposite of the direction of the voltage that drives the motor, because when you cut off the supply to the motor, dI/dt is negative, i.e. the current is decreasing. That is why the diode...
  10. BobK

    Which IDE to start with?

    If you are planning on using PIC I would reccommend MPLAB and whichever C compiler is provided for the PIC you are using (Hi-tech, C18, C30, or C32 ) for 2 reasons: 1. They are free, at least in limited versions that don't have full optimization. 2. You have access for very good support in...
  11. BobK

    unusual signal conditioner needed

    That's even worse. Bob
  12. BobK

    Time activated motorised device for applying light pressure?

    Like making it look like you are working while you are enjoying your life :) Bob
  13. BobK

    unusual signal conditioner needed

    Well, that pretty much sucks, because the underlying chip is almost certainly capable of much better. I don't use arduino, I use PIC, and I have done audio using 50KHz pwm. Bob
  14. BobK

    unusual signal conditioner needed

    A higher PWM frequency would be better. Is there any reason you are using such a low frequency? Also why only 0 to 50%. If you want to use a PWM to output 0 to 5V you would use duty cycles of 0 to 100%, with 0 to 50% you would get 0 to 2.5V out. To use a single stage RC filter, you would...
  15. BobK

    Limit to current?

    The only way to make a motor draw more current is to increase the voltage. bob
  16. BobK

    unusual signal conditioner needed

    You can get an analog voltage from PWM with a single stage RC filter. You will probably need to follow it with am opamp to get a low enough impedance. I have even made audio output using only PWM + a single stage RC filter. Bob
  17. BobK

    Need help with some basic electronics, please.

    So the camera is using 5V x .5A = 2.5W and the solar panel is producing 5W. This is enough to run the camera in full sunlight, but only if you use a switching regulator, a linear regulator would eat up 58% of the power which does not leave enough to run the camera. So with a 90% efficient...
  18. BobK

    What Mosfect acts at Unsmooth DC Voltages

    Ripple in the voltage going into the MOSFET is not going to harm it. Using a 400V MOSFET at 400V likely is likely to harm it. All you need is a little spike to exceed its breakdown voltage, and at those voltages and current it is not likely to survive. Use a MOSFET rated for 600V to be safe...
  19. BobK

    Probability

    The number of possible outcomes of tossing a coin 100 times is 2^100. The number of possible outcomes that have no heads is 1 (i.e. every toss must be a tail). So the probablility of having at least 1 head is that same as 1 - the probability of having all tails. The probability of having all...
  20. BobK

    Simple 555 synth idea

    You might want to look at state variable filters. These can be used to make bandpass filters that are adjustable by a single pot (each) both in center frequency and width of the passband. Bob
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