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  1. dorke

    Stepping up the voltage for a Geiger Counter

    Well, This should be called a "Geiger detector" to make a counter you actually need to count... And there is the possibility to add the ability to know the "strength" of the radiation. You can make it a "Geiger radiation intensity detector and counter".
  2. dorke

    Help with phasors please

    1. Find Z1 and Z2 and apply the current divider rule,it is trivial. 2. -j is -90 degrees.
  3. dorke

    Help with phasors please

    What is it that you don't understand? 1s line is current divider rule applied. 2nd line is KCL applied. 3rd line is KVL applied.
  4. dorke

    EMC test on motors

    All EMC tests must be conducted on all possible ranges of operation(regardless of specific equipment). The one that is of interest is the worst case one. The equipment should complie with EMC regulations in that worst case ,whatever it is.
  5. dorke

    555 timer one shot question

    Welcome to EP. What does the Bluefruit EZ-Key activate, a PC? For windows you can control the repeat rate and repeat delay of the keyboard. By setting them to low you may solve your problem. . Here is a screen shot of WIN XP.
  6. dorke

    What would be the best soldering iron for $200 and under?

    Most probably the cold joints are caused by lacking soldering skills. If you use Chinese cheap solder,it may also be a major factor. Are you a hobbyist ? Here at EP we have a good soldering guide,take a look it may improve your soldering skills a lot.
  7. dorke

    Stepping up the voltage for a Geiger Counter

    Here is another option(adjustable). Have no idea if it is any good. Do you have the datasheet of the tube in English,especially the current ?
  8. dorke

    HP 400F AC voltmeter

    Welcome to EP. Here is the operation and service manual of the HP 400F/FL. Are you able to get mechanical zero?
  9. dorke

    ZIF-sockets from eBay etc -quality OK?

    @TTL, You don't actually need to solder anything. You can insert the zip into the DIP (I did that before,if the zip has reasonable strength pins it is possible, and if you have the height for that 3 level sandwich). ;)
  10. dorke

    Suspected static discharge

    89 Meters is a long nice antenna. It can pick-up fluorescent light ignition,old car ignition, working tool (like a drill) etc. Do you know what type of "input" there is at the dry contact panel? The Coax solution would be very costly,twisted pair may be o.k. A capacitor filter like Steve...
  11. dorke

    Can somebody help how to get desired coil inductance

    An example: iron core, μ=100 diameter 1 cm length 10 cm No of trurns=100 You get 0.99mH (put the values in the calc. and check). Note: 1. the wire is 10/100=1mm thick. 2. you can play with the diameter,length and turns to get the same results in other sizes.
  12. dorke

    Can somebody help how to get desired coil inductance

    Welcome to EP. Here you have a guide and calculator (there are many others on the web). You can also buy ready made standard coils.
  13. dorke

    Ground wire melt from 3d printer board between main and regulator

    Can you show on the picture which wire burns and what AWG it is?
  14. dorke

    NPN transistor still working? Strange ..

    @n_tron, This circuit isn't something to learn from. If at all it may teach you how not to do things! Here is a circuit that can teach you something worth learning, it is also a LED blinker with a UJT transistor (quit an extinct creature).
  15. dorke

    60 Hz line frequecy divided to 1 pps

    Under 1$ is pricey ?
  16. dorke

    60 Hz line frequecy divided to 1 pps

    The LM8560 single IC clock ,in every way better. I'm sure there are others.
  17. dorke

    60 Hz line frequecy divided to 1 pps

    It is obviously intended to be a 24 hour clock. A glance at the circuit diagram reveals that: The left most Nixie has both the 1 and 2 digits connected. All that "mambo jumbo r-c-d" have to do with detecting the "23" hours clock state, after which the next state should be "00" hours. This is...
  18. dorke

    Ground wire melt from 3d printer board between main and regulator

    Yes, This is a current thing. The burnt wire carried to much current for it to handle. The way you wired things isn't desirable. Can you solder? If you can, solder all the wires together and connect them all at the PSU output(star connection),see below. Connected different gauge un-soldered...
  19. dorke

    NPN transistor still working? Strange ..

    The answer to your 1st question is YES. A transistor can operate in the "REVERSE ACTIVE mode",see picture below. In this mode Ve>Vb>Vc (the revers of the active mode in which Vc>Vb>Ve). We still have one of the Tr diodes in forward bias and the other reversed biased. The answer to your 2nd...
  20. dorke

    Arduino based frequency counter design

    Yes Kelly, merely HF;)
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