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  1. HANKMARS

    Transistor as a switch

    Back to observations of a dimly lit design of a motor speed control circuit and their relevance to my disagreement of your definitions or use of terms saturation and fully on. Using my device's data sheets, I did some quick calcs to determine base current limiting resistor values that would...
  2. HANKMARS

    Transistor as a switch

    It has been my understanding that a transistor turns off if Vbe is less than forward breakdown voltage of base/emitter junction. A transistor does not fire (turn on) then need to be brought to 0Vbe to turn off as I think maybe an SCR needs to be. I did say maybe an SCR. I'll have to review SCR...
  3. HANKMARS

    Transistor as a switch

    Footnote: I have no passionate desire that industry abide by my "Definition of Terms." If I were to lead a group on a development project, I would most certainly demand that definition of terms be adhered to. If a majority of the team preferred that the "restroom" be labeled the "water closet"...
  4. HANKMARS

    Transistor as a switch

    I'm unclear to the implication of your statement. Hobbyists would be using proven technologies accepted as convention whereas research seems to search for solutions often based on abstract and theoretical notions. Regardless, views and ideas and information can surely be exchanged between these...
  5. HANKMARS

    Transistor as a switch

    I may have to beg some forgiveness due to a misunderstanding I may have. Personally I define saturation as the state of being "swamped." Saturation to me means that the physical limits of a material has been reached and its ability to absorb, conduct, vibrate with any greater amplitude, etc., is...
  6. HANKMARS

    Transistor as a switch

    Been awhile. I thot hFE was ac gain and beta was DC gain. Not so?
  7. HANKMARS

    Transistor as a switch

    I think I agree. When plotting beta curves, generally Ice is plotted against Ibe. I propose that Vbe could be 5 volts or 50 volts but if current is limited from emitter to base, Ic will behave according to specs.
  8. HANKMARS

    Transistor as a switch

    The device may very well go away as a short lived light emitting device. Most likely, emitted light may be too low frequency to be visible to human eye. A short trail of grey smoke would indicate that all emissions have ceased.
  9. HANKMARS

    Requesting more Greek letters

    Good point about the one, the ell, and the i. I seem to recall that I generally use 12 to 18 point fonts when using word processors, text editors and the like. I most often use the Mongolian Baiti font. Somewhat robust. Now that you mention it, the numeral one and lower case ell appear to be...
  10. HANKMARS

    Requesting more Greek letters

    I often keep windows character map open. Many tables available there. The "not equal to" symbol I used in post #8 was taken from those tables but I had to resize it considerably. Actual size ≠. Hmmm. That one is from Franklin Gothic medium. The one I used in post #8 was about 3 times "dot"...
  11. HANKMARS

    Class D audio amp

    You are most likely correct about this. I was envisioning a high speed crossover "squeak" ( all but eliminated in a quality device ) but even if a distortion was generated at the high freq rate, it would be negated in the low pass output filter.
  12. HANKMARS

    Splatter in relay

    This explanation seems most logical. I knowingly used an "ice cube" type (removable cover) relay in an application which exposed the relay to the weather elements. I constructed a rain cover but it was the airborne particles that crept thru the minuscule openings. I was quite surprised how much...
  13. HANKMARS

    Class D audio amp

    This is the schematic from which I will be working.
  14. HANKMARS

    Class D audio amp

    I think I understand what you are saying here. As the sawtooth starts upward from -s it is out of comparator = -V. When sawtooth crosses Vref, comparator out = +V. However, sawtooth V+ to V- is not instantaneous and I can see how distortion could be created. A triangle wave would eliminate...
  15. HANKMARS

    Class D audio amp

    I'm thinking that a 50% duty cycle of a square wave will produce a more accurate reproduction of the audio range signal. Maybe plug it in to your simulator and look for a bit of difference on the audio out.
  16. HANKMARS

    Class D audio amp

    I agree. Is response time here 200μs or 200ns?
  17. HANKMARS

    Class D audio amp

    Correction. The comparator will be driving a BJT which will drive the MOSFET driver.
  18. HANKMARS

    Class D audio amp

    I am constructing a class D audio amp. The plans I have are using am LM393 dual comparator for mixing audio signal with high freq triangle wave. The response time of the 393 is 1.5μs. I suspect that if the response time is this lengthy, slew rate also is lengthy. My triangle wave is at 200KHz...
  19. HANKMARS

    NiMH battery pack mystery

    I ordered and received more 6 slot battery holders. They ohm out at 0Ω and I am assuming that 0Ω across the interconnecting spring wire is pretty close to actual resistance. I find the fact that the 8 slot battery holders I purchased have such a high resistance value on each internal connector...
  20. HANKMARS

    NiMH battery pack mystery

    Right. A determining factor of how many cells I need in series is a function of required current and load resistance. Ballpark values here are a 4Ω load and desired current of 1.5 amps. Therefore my battery pack needs to present no less than 6 volts across the load. In one of the applications of...
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