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  1. dorke

    Newbie question about transformer inputs

    While feeding the 120V connection there is voltage induced on the 227V wire(auto transformer effect) as well as on the secondary. What you describe sounds like the drawing below. If indeed so ,this suggest a very dangerous situation: :eek: You either don't have an RCD(Residual-current device)...
  2. dorke

    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    "In this case the three holes should have the same voltage, which agrees with the circuit diagram from which we can see the non-inverting and inverting input and output have the same voltage." I don't see any connections like that,only pins 1 and 2 of the op.amp are connected together in the...
  3. dorke

    Varicap @ mV or even µV?

    Moritz, What is the frequency range you are going to operate at?
  4. dorke

    Help!!Elenco XK 300 micro controller system

    Try contacting Elenco directly here. Here is some very basic info on it ,and here is the MEK6802 board it is based on. If there is something specific you need,come back and ask. BTW, This is 1980 stuff,what do you intend to use it for? You can do much better and with greater ease with modern...
  5. dorke

    Most common failure survey.

    No,not at all! I was answering this question(reply #11), about controller or a processor chip: "How often do you do the obvious repairs only to find that a controller or processor chips is toast?",Not the cap issue. I'll post it again for clarity: It is quite rare. In cases it does happen it...
  6. dorke

    Most common failure survey.

    One to add to the list: Rubber bands ! In motor driven equipment(DVDs,CD players,VCRs,Tapes etc.) they are the number one problem. With time they dry out...
  7. dorke

    Most common failure survey.

    It is quite rare. In cases it does happen it is very likely the all board is toasted. That mostly happens because of : 1.Mains power surge. 2.Power supply failure,such that creates a VCC above ICs max absolute value. 3.Lightning.
  8. dorke

    Most common failure survey.

    That has to do with the Taiwanese capacitor plague . If you have a genuine cap from a respected company it can last much longer.
  9. dorke

    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    From the Datasheet block diagram(pp.13) it is clear that SI (Sensor- Input ?) is an input. It is pin 8(pp.45),therefor what you marked as SI in red isn't SI. I assume that SI is buffered by the op-AMP for off-board optional use. I don't know why the yellow lines go towards the AT1006 IC.
  10. dorke

    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    It is very hard to get to get to any conclusion from the board photo, because this may very well be a multiplayer board. and the piggy-back board blocks the view of the traces on the photo. The op-amp connections are clearly an optional one on the evaluation board. The number 1 and 2 pins of...
  11. dorke

    Schottky Diode - Open Circuit

    The 1M should be high enough,it will create a 9uA(not very low,but low) discharge current. How long should the battery hold? Is it a rechargeable battery? How long does it take for the battery to discharge? Or how long does it take to drop from say 9V to 8V? Can you please post photos of the...
  12. dorke

    Schottky Diode - Open Circuit

    Yes, exactly.
  13. dorke

    Schottky Diode - Open Circuit

    "-Is it possible for Diodes to become resistive?" Yes.it is possible but mostly they would be either short or open. "-If so.. Is this the defect im looking for?" Could be,but you should also check the resistance seen by the battery (faulty diode pulled of circuit). "-What can cause batteries...
  14. dorke

    z parameters applications

    Well, Your RF instructor was correct... S parameters and ABCD parameters are suited for transmission lines. That is the major thing concerning RF design/testing (impedance matching etc.) Haven't seen a device with no S-parms in it's spec's ? Well that is typical with guys working in RF/μWave...
  15. dorke

    Coil with iron core as a generator

    Perun, Some notes: 1)Your drawing at reply #3 may suggest you plan to put the coils on the spokes of the wheel. That is obviously not the way to go: The Magnet(s) go on the spokes (moving) The Coil(s) go on the Nave(stationary). 2)Use a filter electrolytic capacitor on the output of the...
  16. dorke

    Vintage Heathkit 4001 weather station how to split sensors between two consoles

    Bob, My pleasure :) When I read your post, I said to myself, that heath company did everything apart from a coffee maker... I found the 4001 manual at this great site on the Web(agree it has totally changed the world,mostly for good). Since it said "Digital Weather Computer" and 1978, I was...
  17. dorke

    Vintage Heathkit 4001 weather station how to split sensors between two consoles

    O.K The distance is big enough so that parallel connection of the "TTL" lines will probably not work. The solution could be RS-232(15 feet), a better solution is using differential line connection(aka RS422): You will need 4 pairs for direction and another one for speed. For each input to the...
  18. dorke

    Parts to a good home

    Sounds like a lot of Santa helpers around... ;) That is nice Amigos ,very nice indeed :)
  19. dorke

    Exactly how evil are Capacitors?

    Well, In order to know what can be stored in a capacitor, you only have to look at 2 things, both are written on in: voltage rating and capacitance. You should assume it is charged fully! Q=C*V A.I don't recommend discharging batteries or super-caps, just be very careful with them(don't...
  20. dorke

    Coil with iron core as a generator

    What do you mean when saying "power production." Are you looking at a bicycles or something else?
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