Search results

Search Forums New Posts
  1. hevans1944

    'Human body only" sensor

    For maximum security, another human being is the best and most reliable detector of another human being. Trained dogs, however, come in a close second, and dogs are good at detecting and following a scent trail if pursuit and apprehension are necessary. A trained-up human and dog pair is a hard...
  2. hevans1944

    electronic load

    @tasty You are conceptually incorrect in your application of the 10N60 MOSFET as a "variable resistance" electronic load. This device is intended to be used as a high-speed electronic switch, being either turned ON with low resistance from source-to-drain, or turned OFF with high resistance from...
  3. hevans1944

    Analog Circuit to Randomly Modulate Amplitude and Frequency

    Laboratory experiments relating to plant growth? If this were really a laboratory experiment instead of some fanciful pipe dream, you would realize that well-designed scientific laboratory experiments are always deterministic: to be a valid laboratory experiment that follows the "scientific...
  4. hevans1944

    Where could I salvage an LM317 Voltage regulator?

    Talk about going off half-cocked! The usual laser diode inside a DVD player has a built-in short focal-length lens optimally selected to focus the laser spot onto the rear surface of the plastic DVD, thereby allowing microscopic "pits" that encode the DVD content to reflect (or not) light back...
  5. hevans1944

    Analog Circuit to Randomly Modulate Amplitude and Frequency

    You haven't told us yet what you are going to DO with your randomized signals. Like, what "specialized visual effect" do you intend to create, and more specifically, how do you intend to create the effect? What hardware does the sine wave of randomized amplitude and frequency drive, control, or...
  6. hevans1944

    Capacitor with conductive metal inbetween plates

    You might want to investigate how supercapacitors are made. They are essentially two capacitors in series, but with the common electrode inaccessible because of the design. Therefore the effective capacitance is half that of either of the two capacitors in series. If these two capacitors are 100...
  7. hevans1944

    Op Amps

    If this were the usual op-amp circuit, with non-inverting gain for a single input applied to the (+) input, then you could say that the "gain" for that input is 1 + Rf / Ra. You should derive this equation yourself to prove you know what you are doing. However, it becomes a little more...
  8. hevans1944

    Op Amps

    Since this is homework, we aren't going to solve your problems for you, but here are a few tips to get you started... First, assume the op-amp has infinite gain. This means that for a finite output Vo = 5V that Vp-Vn = 0; that there is no current flowing between the inverting (-) and...
  9. hevans1944

    Switches

    Any idea what physical size is acceptable? Contact voltage and current ratings? Toggle switches with a spring-return to center-off position are commonly available as DPST and DPDT two or three position switches. The ones that return the switch to the centered position when released are...
  10. hevans1944

    Angular parallel plates capacitor

    To determine electrical field edge-effects requires a calculus not often seen in these forums. What are you trying to DO? Why is bending the parallel plates important to you? How much math are you prepared to learn (or have already learned) to set up and solve the equations necessary to...
  11. hevans1944

    Video signal amplifier.

    @WHONOES: Don't forget it also has to operate a video amplifier driving five hundred feet or so of whatever wind-up cable, and presumably also power-up a lipstick camera at one end of the cable and perhaps an LCD monitor at the other end. The excursion to the African Congo seems to be a new...
  12. hevans1944

    Articles- Slight Error

    I practice my Roman numeral proficiency by trying to read the copyright date on movies, as it goes flying by at the end of the movie credits.
  13. hevans1944

    Shock from arduino

    My interpretation of "referenced to earth ground" does not mean "connected to earth ground." I am using "referenced" in this context to mean "measured with respect to." Please accept my apology for any confusion my interpretation may have caused. Here in the USA, typical house wiring is...
  14. hevans1944

    Shock from arduino

    Thank you! It looks like one of these will "protect" the end-user from electrical shocks that result from no less than either 10 mA or 30 mA (depends on model) of unbalanced current between the "active" and the "neutral" AC power lines. This will be true whether either the "active" or the...
  15. hevans1944

    Shock from arduino

    @Bluejets: Will those "safety switches" still work if they are plugged into receptacles that do not have a good earth ground? I know nothing, zip, about such things, but imagined they were somehow a combination of circuit-breaker and ground-fault circuit interrupter or GFCI. A circuit-breaker...
  16. hevans1944

    Video signal amplifier.

    Edison's electrocution of animals, including an elephant, was quite well documented on motion picture film. No hearsay involved. Today, the transmission of DC power at megavolt potentials is a "done deal," both in the USA and abroad, because of the availability of solid-state switching devices...
  17. hevans1944

    Video signal amplifier.

    Dead reckoning? That's a navigation procedure I haven't seen used since GPS became widely available worldwide. My father used to use dead reckoning to plot the course of the B-47 bomber he was responsible for navigating from his base in the United States of America (USA) to some target for his...
  18. hevans1944

    Shock from arduino

    AC power distribution wiring in India can be problematical. Proper grounding often does not exist. It would be a good idea to hire a licensed electrician to check, and it necessary repair, the AC wiring you are using.
  19. hevans1944

    Video signal amplifier.

    Tom had a huge vested interest in DC dynamos, which is why he vigorously opposed AC power distribution. Tesla and Westinghouse owned the patents to polyphase AC power distribution, and given the shabby way Edison had earlier treated Tesla, Tom was not likely to have obtained licenses to use them...
  20. hevans1944

    how to post a picture

    Perhaps you should get someone to help with your English. You said "i explain :" but your explanation does not make any sense. You DO NOT "past" anything in the text area. If there is something stored on your browser's clipboard, you can paste the clipboard contents into the text area by...
View older results
Top