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  1. D

    Building a 4 poles filter

    "Dish", a flat top ? Or equaripple Cheby ? Your link takes one to - Regards, Dana.,
  2. D

    Super Capacitator Charging

    Be aware of transient behavior of reg on startup, load connect (violating super cap limits) - Your datasheet has no graph, I took this one from a generic reg. Also its operating conditions regarding output C ESR.... Regards, Dana.
  3. D

    Super Capacitator Charging

    Most regulators have current and thermal limiting. If the reg goes into thermal limiting it will oscillate at real low freq because of the thermal time delay inherent in a thermal mass heating and cooling. Basically reg shuts off, cools down, then turns on again. In your case it may be the...
  4. D

    Pot identification and alternative

    What is the function of the board you are repairing ? Regards, Dana.
  5. D

    How do I determine if an RF signal is transmitting? Re: Weather station

    Yes the SDR "should" have enough sensitivity. Regards, Dana.
  6. D

    Problem with Ramp signal Generator using IC 555

    Did you measure the accuracy of your R & C used in timing loop ? Datasheet says - What accuracy are you seeking ? Fixed frequency or variable needed ? Regards, Dana.
  7. D

    Transistor as a switch

    Not that there is WW police watching any of this, I always thought HFE is DC,. hfe is AC. But who is going to police US other than US ....and is hFE a trans transistor.....a little bit of both..... Regards, Dana.
  8. D

    Transistor as a switch

    From the Art of Electronics, Horowitz, bipolar saturation, attached. Regards, Dana.
  9. D

    Transistor as a switch

    I had a project where I had to make a fast HV power switch, back in the 70's, so delidded several TO3 like this, chained them into a serial circuit C-E-C-E... and used a photo flash to switch them on. Worked with uS kind of performance. Fun stuff. Regards, Dana.
  10. D

    Transistor as a switch

    This is an interesting simplified summary of saturation - I would be careful however, this is a Prof talking and as we have warned earlier in thread academia not good. Also its pedantic, although since Prof used no field theory I would venture he is only 10% pedantic on the scale, so if any...
  11. D

    Transistor as a switch

    Somewhere North of 1.4V looks like, and the above is just typical. Use Vbe @Vce = 4.0 curve if you want it in linear region. Regards, Dana.
  12. D

    Transistor as a switch

    Thanks for the correction, my ADD saw that plot rising to the right and bingo, bigger is more in ADD land. I stand corrected. Regards, Dana.
  13. D

    Transistor as a switch

    I always thought of this as an DC effect, but it does show up in switching characterizes when a base is saturated with current and effects incurred due to storage time. Wiki def of saturation - https://en.wikipedia.org/wiki/Bipolar_junction_transistor Regards, Dana.
  14. D

    Transistor as a switch

    Yes - The model used in this simulator seems to account for saturation effects - https://help.simetrix.co.uk/8.0/simetrix/mergedProjects/simulator_reference/topics/simref_analogdevicereference_bipolarjunctiontransistor_spicegummelpoon.htm Regards, Dana.
  15. D

    Transistor as a switch

    Then there is this, eg. all bipolar, or so I think (vert axis is Ic)- Ebers-Moll has no total shutoff (due to leakage) - Gummel-Poon - https://www.iue.tuwien.ac.at/phd/rottinger/node61.html By the way Ebers-Moll & Gummel-Poon are right about this for the deniers. Regards, Dana.
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    Transistor as a switch

    No worry of the feathers, they are clean and flight ready. Pedantic, challenge for you is accuracy, then you can join us PEDs in knowledge land, ready to accept all who try and care about accuracy. Who adapt to new knowledge evolution from new evolving scientific findings. Regards, PEDEE here.
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    Transistor as a switch

    Looks like a better def is when CB junction becomes fwd biased - Even more definitions - https://www.quora.com/When-can-we-say-a-transistor-is-saturated Be aware there are more peds and techs and wannabees over there.... Regards, I love education.....
  18. D

    Transistor as a switch

    Ok then, education apparently now a problem for you. I will pass on further discussion with you on this issue. Regards, Dana.
  19. D

    Transistor as a switch

    This is what caught my eye..... And we have not even discussed finite geometries and their effects..... Regards, Dana.
  20. D

    Transistor as a switch

    Thats not true. From Sze, 3'rd edition, semiconductor physics, the drift velocity reaches a saturated value, for which the current density is dependent on, hence also saturates. Saturation current become drift dominated when CB becomes forward biased. Regards, Dana.
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