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  1. hevans1944

    Grounding and Circuit Noise

    Well, clearly @AdamZ is still having problems. His is a difficult task, if you read and understand the paper cited in the previous thread. This is basic R&D done at the molecular level. Adam has lots of spiffy tools, such as electron microscopes and a National Instruments data acquisition...
  2. hevans1944

    Problem reading frequency using arduino on pin f5

    This is a popular inductor and capacitor measuring circuit. It is based on measuring the frequency change that occurs in an LC oscillator when the unknown inductor or the unknown capacitor is placed in parallel (capacitor) or in series (inductor) with the built-in L and C oscillator components...
  3. hevans1944

    Grounding and Circuit Noise

    Thus thread appears to be a continuation of problems discussed on this previous thread. Visit the previous thread for more background information.
  4. hevans1944

    doubts on projectors

    Yeah, it's all magic. You just need to interface the cell phone to the projector with a wi-fi or Bluetooth app. Can't help you there, but someone here probably can help you, now that what you want to DO is more or less defined. Wait for them to reply.
  5. hevans1944

    How to detect very high frequency sound ?

    I really do love Man's Best Friend. Currently between dogs (and cats) right now, but we will get a puppy either this year or after we move to Florida. Blue eyes optional in either animal, but I am partial to blue-eyed, short-haired, Siamese cats and largeish dogs. Rottweiler/Labrador mixes...
  6. hevans1944

    doubts on projectors

    So, did you even look at the projectors I linked to in post #3?
  7. hevans1944

    Making prison safer...

    In a just system that would not happen, but it does. There are various levels of confinement, from ankle bracelets with defined perimeters of containment, to "black holes" no one escapes, and lots of things in between. The prison system rarely "rehabilitates" anyone. It does do a fair job of...
  8. hevans1944

    doubts on projectors

    Based on your inability to tell us what you want to DO, we cannot tell you how to "do the circuit". What does it mean, "the displayed information must be on the floor..." combined with the statement "...but not through any displaying device like LCD etc." How do you want to "display" the...
  9. hevans1944

    Making prison safer...

    Isolation of convicts to protect society from them is as old as human history. Something to do with our innate desire NOT to execute every miscreant society deems unacceptable to live with. The extra security of storing people in orbit, or on the moon, or on an isolated continent (as was once...
  10. hevans1944

    Can someone help describe how this circuit works?

    Aw, come on guys... its four NAND gates, three of which (2, 3, and 4) are wired as inverters. If the loop is closed when the alarm is SET (turned on) via switch SW1, then input to NAND 1 is held low and its output will be high. This is inverted by NAND 2 causing its output to be low. The low...
  11. hevans1944

    convert a 3 phase 1 hp ac motor to 12 vdc

    And what is the power source for the alternator? Perhaps you can use the pumped crude to run a small diesel engine? Or burn it to operate a steam engine? Why would you even need an alternator if you have solar to charge batteries? How many wells do you have, and what is the distance between...
  12. hevans1944

    doubts on projectors

    Or check out some of these projectors offered by Amazon. Some are small enough to fit in the palm of your hand. Why re-invent something you can purchase off-the-shelf?
  13. hevans1944

    How to detect very high frequency sound ?

    Well, if so, the usual suspects would be any or several three-letter Government agencies, but what makes @dxpwny worth the effort to do so? There are more than 7,404,976,783 people currently occupying space on Mother Earth, and only a very small, almost insignificant, number are persons of...
  14. hevans1944

    Differential Configuration for a Floating Signal

    Oh, I forgot to mention that smaller-valued bias resistors are better, as long as the application can tolerate the decreased differential input resistance. Smaller valued bias resistors decrease the differential offset voltage created by the bias currents, and also decreases the Johnson...
  15. hevans1944

    How to slowdown capacitor discharge

    I believe you can learn by doing, but I also believe in learning from the experience of others, and to temper this with good theory that explains results and successfully predicts future results. That is the scientific method, and it is how this forum works. Life is too short to chase an idea...
  16. hevans1944

    Differential Configuration for a Floating Signal

    Differential amplifiers, even those with FET inputs, have bias currents at their input terminals. These currents need to be returned to circuit common or they will charge up the capacitance between each of the input terminals to circuit common and drive the amplifier toward either the positive...
  17. hevans1944

    Detecting solenoid ON and OFF state

    You don't need a backup battery for the loom. When the loom is turned off, the shutdown program sends data to the EEPROM which stores the information required to start up again. The EEPROM stores the data indefinitely, ready to be retrieved when the loom is turned on again... even if that is...
  18. hevans1944

    Detecting solenoid ON and OFF state

    Hard to say without being there to observe your problems. I realize utility power is sometimes unreliable in India, so perhaps using a large capacitor as a back-up power source makes more sense than trying to maintain the charge on a battery during long periods when everything is idle. You would...
  19. hevans1944

    Making prison safer...

    Read the short story "Coventry" by Robert A. Heinlein. His "solution" (in the story) is to send all prisoners to a "free for all" enclosed area, about the size of a state perhaps, with an impenetrable wall surrounding Coventry. The "prisoners" sort things out among themselves, isolated from...
  20. hevans1944

    Detecting solenoid ON and OFF state

    I suppose you could write current data (whatever that is) to the EEPROM as often as the current data changes. An EEPROM is non-volatile, so when power is restored the last "current data" that you wrote to the EEPROM would still be there. Problem with that is if the "current data" changes a lot...
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