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  1. dorke

    Gate driver datasheet for IGBT

    Well, Vref is an internal voltage reference source. Look below for the "block diagram " of another voltage regulator. The LM317 works the same. It has it's internal voltage reference Vref. but the connecting circuit is a bit different.
  2. dorke

    Gate driver datasheet for IGBT

    Making assumptions of what people touch or not has very little relevance in many situations(e.g. a service technician may open and touch,somone can touch the load etc.) . You need to think about a faulty situation not a normal working circuit. e.g. Look at the pic below,now think about a...
  3. dorke

    Gate driver datasheet for IGBT

    Jeroen, Your questions suggest you have very little experience if at all. Try reading the datasheet,take your time to get a basic understanding of how this regulator works. This isn't a fixed voltage regulator it can be adjusted to any voltage in the allowed output range. The mains isolation...
  4. dorke

    Gate driver datasheet for IGBT

    I think that in this application the load switched by the IGBT will most probably be the limiting factor . Is your load purely resistive ?
  5. dorke

    Gate driver datasheet for IGBT

    There are a few problems here: 1 .The power supply circuit isn't mains isolated -that isn't a good thing. I would change that to an isolated one. 2. The power supply needs to supply a vary low average current of 3ma. The device may draw peaks up to 4A during the switching period(that is taken...
  6. dorke

    Ok guys, heres another amp conversion question...

    Electrocution? only if you have either of the devices already zapping you...
  7. dorke

    Gate driver datasheet for IGBT

    The important thing is to have 15V < VCC-VEE < 30V. They can be any voltage you like. If you use 15V as VCC then VEE is 0V. But that isn't recommended since you do have a voltage tolerance on the power supply. So you should go higher to guarantee the minimum requirement of 15V. The device has...
  8. dorke

    Scope calibration

    I don't. but here is a link to the service manual of the HP1741A. It should answer all your questions including calibration.
  9. dorke

    Scope calibration

    You do have a CAL point on the scope. Are you working in "main mode" or mixed or DLYD ? Is the scope not calibrated in all time base positions? By how much in % is it not calibrated?
  10. dorke

    B & O Penta amplifier repair and Tr equivalents

    NO, R83,R88 are part of the over current protection circuit , with TR17 and TR18. If you intended to operate the AMP without the finals: 1. Before applying power ,do this test again (from #18): Test resistance between output (L1) to GND and ±68V rails. 2.With power Adjust R59 for zero Vdc at...
  11. dorke

    Scope calibration

    It is possible. But first, is the vertical vernier in the CAL. position?
  12. dorke

    Frequency divider (less than 1MHz)

    Here is another,more complicated idea : "pitch shifting". 1. Sample the signal at a high frequency fs (more than twice the Nyquist rate-in your case 1M*2= 2Mhz) by a fast A/D with enough resolution. 2. For every 4 Samples , produce a single one "output sample" Vs. 3. Convert the Vs samples...
  13. dorke

    Kinetic Phone Charger

    Welcome to EP. Sound like you have soldered a diode directly across the output of the device. A clear photo may help.
  14. dorke

    Info for 2N3904 and 2N3906

    Just to make things clearer: The term "complementary pair" is indeed refereed to NPN and the accompanying PNP BJTs. But only when they have the very same characteristic parameters, i.e. they are closely(not perfectly) matched in that aspect. The 2N3904 and 2N3906 are a "complementary...
  15. dorke

    Fluke 89iv funny reading

    1. Measuring voltages with wires not touching is mostly meaningless (there is pickup from the air ,worse for AC-line pickup). Short the wires, you should get 0.000V in all ranges. 2. In resistance measurement it is fine,you are measuring the resistance of your probes. 3. For more tests you...
  16. dorke

    Info for 2N3904 and 2N3906

    There is a long way for you to go learning. 1. The pin-outs in this case are the same. you should always check the datasheet of the device(as you did) for that. 2. "pinned opposite" is not at all defined ! NPN and PNP can ,and are used in the same project. The way they are connected depends...
  17. dorke

    Mosfet / Gate drive problems

    I forgot to mention what was the Anode(plate) Voltage of that power tube...about 2,700VDC. And that guy,an authorized trained technician should have known better. At our places we say: Not quite the sharpest pencil in the pencil-box... And look here , I'm speechless:eek:
  18. dorke

    Frequency divider (less than 1MHz)

    Here is another (relatively simple?) idea: Convert the above square wave to a triangular-one, then convert the triangle-wave to sine-wave with this differential-pair circuit(taken from TI AN-263).
  19. dorke

    Mosfet / Gate drive problems

    Yes Hop, I'm not a spring chicken anymore, but you have more then a decade on me...;) I also built an AM radio receiver in the high-school perriod. Long time ago I was a signal man myself , the technical side . And talking about a "man who is a couple pints short of a full gallon".;) Is this...
  20. dorke

    Help wiring DPST Switch

    Like Dave said before,it must be a US thing. It is invisible to the earthlings on the other side of the pond,sort of a blind spot I guess;)
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