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  1. hevans1944

    How to measure diesel tank level by pressure sensor, tank area and diesel paramenters

    I am gonna bump this old thread by suggesting that the simplest method of measuring the volume of fuel in a tank is to weigh the tank. That means the tank(s) must be mounted on load-cells, perhaps more than one for each tank, but at least all the necessary wiring and signal conditioning is...
  2. hevans1944

    Got any ideas for using an old fridge?

    Are you sure an oxy-acetylene torch is necessary for brazing? How about a MAPP gas torch? However, even with the requisite equipment, a one-off project like this is probably not worth your effort since there are many folks here that really need your help and advice. And, yeah, watch out for them...
  3. hevans1944

    Capacitive reactance affecting voltage divider output

    What does this even mean? What is "the feedback gnd and supply of the piezo?" It's nice that you are trying to "help" your friend, but coming here and presenting isolated bits and pieces of the puzzle doesn't help anyone and is a huge FWOOT. So, you have revealed that a PIC microcontroller is...
  4. hevans1944

    Capacitive reactance affecting voltage divider output

    Please answer my questions (3) and (4) in post #8. What are the two capacitances C1 and C2? Why are they in parallel? What do these two capacitances represent? What is the purpose of the 3V at the top of your diagram? How is power applied to the piezo sounder to make it operate? Does is require...
  5. hevans1944

    Capacitive reactance affecting voltage divider output

    (1) Try using the correct equation for capacitors connected in series, as @Harald Kapp suggested in his post #3. The correct formula is the reciprocal of the sum of the reciprocal capacitances, NOT the sum of the reciprocal capacitances as you mistakenly stated. (2) Provide the actual values...
  6. hevans1944

    Electronic Relay

    We have a 2002 Ford Taurus Station Wagon, now with over 250,000 miles on the odometer. We purchased it used from a dealer, who has since gone out of business (Planet Ford, Centerville, OH), to replace an earlier model-year Taurus Station Wagon that I purchased new and drove until the wheels...
  7. hevans1944

    icircuit

    If I were a moderator of this forum, and I observed a member consistently making simultaneous duplicate posts on other forums, despite repeated warnings that such posting are not acceptable forum behavior here, I have a much simpler solution than not answering those duplicate posts: Ban the...
  8. hevans1944

    Replacement for AD630 for the purpose of Lock-in Amplification

    Who gave you this absurd task and told you it had anything at all do with "a study of the waveforms generated from human brain?" It doesn't. Maybe you should review some of the research already performed in the study of human brain electrical activity. Here is a link to a place to start...
  9. hevans1944

    Replacement for AD630 for the purpose of Lock-in Amplification

    The usual approach is to use a mixer and a local oscillator to translate the information spectrum of the megahertz signal to a lower baseband frequency. But you haven't provided any information about the information spectrum of the megahertz signal. Please tell us WTF you are trying to do and...
  10. hevans1944

    Upper frequency limit of an oscillator

    When I fired up my LTSpiceIV and tried to "Sync Release" from the Tools menu choice, it failed to do so. So I went to the website and downloaded the latest version of LTSpice, which happened to be LTSpice XVII. Easy peasy and I was up and running in no time. Had a few false starts (probably my...
  11. hevans1944

    Upper frequency limit of an oscillator

    I remember the origins of SPICE (Simulation Program with Integrated Circuit Emphasis) from the 1970s while pursuing an electrical engineering degree, part-time, while working full-time for the University of Dayton Research Institute. It came out of the semiconductor integrated circuits...
  12. hevans1944

    Upper frequency limit of an oscillator

    Reading this thread became so frustrating that I fired up LTSpice XVII and modeled the stupid oscillator myself. Like @Audioguru said: most of us build a real circuit. I have all the parts to do so, except for the two BC846B transistors, for which I would have to substitute 2N3904. The...
  13. hevans1944

    icircuit

    According to the information at the bottom of this page it does: Have you made friends with Google yet? It can save you a lot of time finding answers to questions that have already been answered.
  14. hevans1944

    icircuit

    There is a protocol for posting the same question on multiple forums: First, post the question on just ONE forum, although you may be a member and have posting privileges on other forums. Second, wait at least a few days for a response. Third, if someone does respond, enter into a dialog with...
  15. hevans1944

    Upper frequency limit of an oscillator

    I would try both. Increase the value of the collector resistor so saturation occurs at something less than ten milliamps, say 1.5 mA and at Vce (sat) = 250 mV. Decrease the base resistance to make sure the transistor is driven into saturation, Vbe(sat) > 700 mV. Increase the capacitor values to...
  16. hevans1944

    Tek 475 scope

    Really? I am sorry you feel that way as I have seen @dorke give some very helpful advice to newbies on other threads. Quoting from your first post: You got your "someone with experience on scopes" who started to give you some step-by-step suggestions, but it is clear from your response you...
  17. hevans1944

    Electromagnet vs Neodymium magnet

    In general: No. The magnetic field produced by an electromagnet is temporary, and its strength is determined by the current in the electromagnet: more current produces a stronger field. No current means no magnetic field (except for a very small residual field) so, as @kellys_eye mentioned...
  18. hevans1944

    What to Do With a Lot of Salvaged Speakers?

    Back in the day, I sometimes salvaged the magnets from small loudspeakers. However, better, stronger, magnets can be salvaged today from the internal works of hard-disk drives with a lot less trouble. Nostalgia is okay. But my remembrance was hiding a low-wattage night-light on an extension...
  19. hevans1944

    Internet schematic OK

    According to his information page, he is retired and disabled. Perhaps hand-drawn schematics is one form of therapy for him, just like picking up electronics again after age 9 and his frightening experience when Static balls are no fun to play with, what with all the hissing and sizzle and...
  20. hevans1944

    Internet schematic OK

    Ah! I keep forgetting Google can search images...
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