A look at the dual bipolar transistor zener clamp circuit, and it's usefulness as a fast low leakage overload clamp.
The first part is lifted from video #1000 with 12 minutes of extra commentary.
Interview with Dave Taylor, designer of the famous Fluke 8060A multimeter:
https://theamphour.com/180-an-interview-with-dave-taylor-multi-talented-meter-maker/
Forum: http://www.eevblog.com/forum/blog/eevblog-1157-transistor-zener-clamp-circuit/'>http://www.eevblog.com/forum/blog/eevblog-1157-transistor-zener-clamp-circuit/
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Done.

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By YTB

22 thoughts on “Eevblog #1157 – transistor zener clamp circuit”
  1. Avataaar/Circle Created with python_avatars gary granato says:

    brilliant vid

  2. Avataaar/Circle Created with python_avatars Fiyor Bahr says:

    Thanks for the lecture, if you have tutorials how to make analog transmitter and receiver pls 🙏 teach us.

  3. Avataaar/Circle Created with python_avatars Gunter Flunder says:

    In fact you allready need an enhanced Vebo if you want to operate the standard astable multivibrator design at voltages above 5 V.

  4. Avataaar/Circle Created with python_avatars Hola! Brenton says:

    Are these faster than a Transorb or regular Zenner?

  5. Avataaar/Circle Created with python_avatars AMPLIFICADOR TRANSFORMADOR says:

    very good, we are brazil country soccer.

  6. Avataaar/Circle Created with python_avatars Peter Müller says:

    How fast is this? Would it be useful against ESD or is it too slow?

  7. Avataaar/Circle Created with python_avatars Eric John says:

    Ran across this looking up what this transistor configuration does after seeing it in a schematic from early 1960's.

  8. Avataaar/Circle Created with python_avatars Krutarth Mehta says:

    some people make relaxation oscillator , using this property.

  9. Avataaar/Circle Created with python_avatars Pierre FPV says:

    Hi Dave, I tried this out with a bunch of transistors from my jellybean box, (noname BC547,BC548,BC549,BC550,2N2222,BC557) however I couldn't get anything less than 10V Vebo. Most are around 10.8V am I doing something wrong? I used a 2K series resistor and 12.3V input.

  10. Avataaar/Circle Created with python_avatars Brendan Robertson says:

    Hey thank you so much for this channel; especially Fundamental Fridays! After years of being a professional programmer, I've started down the path of E.E! Most tutorials on youtube never go into enough depth & are always hum-drum (BORING) on a subject. After going through your series, even though sometimes years old, it seems timeless. Schmitt Trigger, Zener Diodes, Transistors, Opamps, Overload detectors etc. Not only informational, but fun at the same time. Here's a how ya doin' from Canada! Cheers

  11. Avataaar/Circle Created with python_avatars JAMES T. says:

    The fluke clamp! I'm just a dumb guy trying to learn something, but could this type thing be used in solar lightening arrestors? I don't know why they call it that, I haven't seen much that's can save you from lightening! I have always figured it protects from the static build up before of after near by or near strikes,

  12. Avataaar/Circle Created with python_avatars FPV Enthusiast says:

    Just starting my journey into electronics, but how does a varistor compare to this solution ? Varistors are available in many flavors and clamping voltages.

  13. Avataaar/Circle Created with python_avatars Gordon Brown says:

    Would this set up be used for intrinsic safety circuits? The Atex Ex i a ratings.

  14. Avataaar/Circle Created with python_avatars Brian Link says:

    Maybe as a distortion circuit??

  15. Avataaar/Circle Created with python_avatars NoSuchThing says:

    Hi?

  16. Avataaar/Circle Created with python_avatars Pranav Joshi says:

    As per my understanding, avalanche breakdown can do permanent damage to a semiconductor device if the current is not limited. What is special in this circuit that prevents BJTs from getting damaged permanently?

  17. Avataaar/Circle Created with python_avatars Mark Rowland says:

    Dave, can you quote approximate collector current in the upper transistor above and below the "zener knee"?

  18. Avataaar/Circle Created with python_avatars Anuj Arya says:

    I think you told abt this while reverse engineering a fluke multimeter??

  19. Avataaar/Circle Created with python_avatars Joost Breed says:

    The title says clamping. But shouldn't it be clipping instead? I thought clamping was about biasing.

  20. Avataaar/Circle Created with python_avatars Ken Nener says:

    Very nice. I had totally forgotten about this, but I used to use reverse-biased B-E junctions as voltage references in regulated power supplies 40 years ago. How about white-board episodes covering other "lost arts"? Two suggestions: simple BJT transistor oscillators, and running simple CMOS logic gates as linear amplifiers (RCA used to publish apps information on that).

  21. Avataaar/Circle Created with python_avatars Paul Badenhorst says:

    Would a "Capacitance Multiplier" be an input protection (reverse polarity)?

  22. Avataaar/Circle Created with python_avatars Bob Vincent says:

    Regards inventing the wheel?.

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