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  1. BobK

    PWM Audio

    No, it is not 10 high or low values that are representing the audio level, it is the length of the high part of a variable duty square wave. This length is a continuum with no steps at all. Lets look at it this way, representing a DC signal of various voltages. The PWM period is, lets say...
  2. BobK

    How to connect POT and how this regiulator based charger behaves?

    But note that how you connect it determines whether resistance increases or decreases as you turn the pot clockwise. A volume control wired the wrong way would be rather annoying. Bob
  3. BobK

    Some questions regarding AC-DC SMPS adapter OP etc

    Look more closely at the meter, are you sure it was not millivolts? Bob
  4. BobK

    Joule Thief

    You cannot raise voltage and current, that would be free energy. The Joule thief is a boost converter, probably the simplest one that anyone could come up with. It is totally unregulated. The fact that and LED is driven provides a limit to the voltage it outputs. If you replace the LED...
  5. BobK

    Converting from AA to Li-Ion

    Li Ion battery packs normally contain current limiting electronics so that they are not dangerous. If you were to buy raw cells, you would have to add protection. Bob
  6. BobK

    How to connect POT and how this regiulator based charger behaves?

    That is correct. Often a pot is only needed as a variable resistor, which is the case here. In that case, you connect one side end to the wiper (or leave it off, it does not matter since you are basically shorting out the part between the wiper and the end it is connected to. The pot you...
  7. BobK

    Time for an old dog to learn new tricks!

    Yep, LTSPCE from linear.com. And I can attest to it as an old dog that learned it :) Bob
  8. BobK

    Looking for input.

    Why not use a switching regulator controller chip? A converter needs a feedback loop, this is all built into that type of controller, you would be doing it yourself if you used a PWM controller. There are two kinds of chips out there, ones that have an internal switch and those that control...
  9. BobK

    PWM Audio

    Raven, Here is a good paper on class D: http://www.irf.com/technical-info/appnotes/an-1071.pdf The PWM signal is generated completely by analog means, via a comparator and a sawtooth wave, so there is no digitization effect. Bob
  10. BobK

    PWM Audio

    At 200 KHz to get 16 bit resoltution you would need indeed need 13GHz counters. I suspect most class D audio amplifiers don't supply anything like 16 bit accuracy, or they are analog. Bob
  11. BobK

    Need help from all the pros out there...

    PID is a universal control algorithm, it stands for Proportional Integral Differential. These are the 3 terms in an equation that you can adjust, the the algorithm is just: 1. Read the input. 2. Calculate the error (desired vs. current value) 3. Compute the next value of the output (and...
  12. BobK

    How to connect POT and how this regiulator based charger behaves?

    This circuit is essentially the same, coming from the LM317 datasheet. In this schematic it is clear where the connections are. The pot is replacing the 1.1K resistor in this schematic.
  13. BobK

    Need help from all the pros out there...

    Welcome to the forum! So we are getting 2 inputs, one analog (the voltage) and the other either analog or a quadrature encoder. And one output to control a voltage. Your I/O requirements are minimal. I don't see any need for USB or serial comm unless you want to be able to futz with it...
  14. BobK

    How to connect POT and how this regiulator based charger behaves?

    That schematic is ambiguous. The usual convention is that crossing lines do not connect unless there is a dot there, but this is not the case in this schematic. I think the center lug of the pot must be connected not just to the base of the transistor, but also to Rx and the bottom lug of the...
  15. BobK

    Using Logic Systems

    But, excluding the power supply and components needed to interface to the devices controlled, the uController solution would require 3 parts: An 8-pin micro, a decoupling capacitor, and the switch. Then it would need maybe 30 lines of C. Then when your friend says, wow, this is great, but...
  16. BobK

    Am I insane? (and 1 smaller question)

    The biggest problem I see with your path is that you will end up with a programmer but no debugger. The PICKit 2 or 3 has in-circuit debug capability that interfaces with the development environment, letting you set breakpoints and single step on the actual target processor at look at variables...
  17. BobK

    Using Logic Systems

    Well, since you said it was a debate, I guess I will take the other side :) I have been toying with electonics since my teen years, but I never really go into it until I discovered PICs a few years ago. Perhaps that has something to do with the fact that I am a software professional (I have...
  18. BobK

    Current meter is burning out microcontrollers

    ROFL Bob
  19. BobK

    blowing up capacitors

    You know, if you just start designing and building electronic devices, you will certainly get some components to blow up eventually. Bob
  20. BobK

    How to start off in microcontrollers?

    I am late to this thread, and you seem to have changed your mind about doing it from scratch, but I would like to encourage you to rethink that. You might not get something working in an hour like you would with a Arduino, but after you do get it working you will have opened up and entire new...
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