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  1. hevans1944

    Need inductive loop/clamp for A0 input to measure -30 to 80 amps dc

    Sure, but if you do decide to open one of the heavy current-carrying cables, you can insert into the cut cable a short length, say three or four inches (100mm), of three or four parallel-connected 10AWG insulated wires. Feed one or all of these smaller gauge wires through the hole in a...
  2. hevans1944

    Need inductive loop/clamp for A0 input to measure -30 to 80 amps dc

    I really envy those of you who can afford an 80 A solar photovoltaic system of any voltage or peak power capability. As soon as we retired to the sunshine state of Florida we began to be bombarded with offers of "free" solar energy to be installed on the roof of our (relatively) new house...
  3. hevans1944

    Need inductive loop/clamp for A0 input to measure -30 to 80 amps dc

    You could just purchase a small Hall-effect sensor such as this one and roll your own with a toroid ferrite core of appropriate hole diameter to pass your humongous conductor through. (Really? 0 AWG for a measly 80 amperes?) Use a diamond abrasive saw to cut a radial slot in the toroid for the...
  4. hevans1944

    Battery Water Level - Bit above Green Line

    My, my! How fancy! I think you are okay on the very slightly overfilled battery cell, since you didn't spill any battery electrolyte while adding distilled water a few drops at a time. And you did the right thing by not allowing the electrolyte level to fall below the red line. The battery...
  5. hevans1944

    How to create an equation to solve for resistance in this circuit

    As an electrical engineer, I KNOW my education didn't focus enough on the fundamentals of programming. Apparently that kind of instruction was reserved for Computer Science majors. The only required course for me was one semester of FORTRAN. BASIC was available as an interpreted time-shared...
  6. hevans1944

    How to create an equation to solve for resistance in this circuit

    My oldest son had an RPi on his desk, along with a nifty plastic box to enclose it. When I expressed an interest in it, he picked it up and gifted it to me. I had just started playing around with Arduino Unos and assorted shields available for same at Radio Shack, so the RPi was relegated to my...
  7. hevans1944

    How to create an equation to solve for resistance in this circuit

    You have stumbled onto just about the worst web site, Instructables, for any beginner to learn electronics. While technically correct in approach (measure the voltage across the unknown resistor and divide by the measured current through it) the author poorly describes the process that is...
  8. hevans1944

    How to create an equation to solve for resistance in this circuit

    The current through R1 and R2 (in series) from the voltage source Vih is i = Vih / (R1+R2) (1) The voltage Vout = i (R2) (2) Both of the above two statements are algebraic statements of Ohm's Law: E = I x R or I = E / R or R = E / I. These three equations are all statements of Ohm's Law. So...
  9. hevans1944

    Why is this Happening to Me?

    I remember opening up my first "pocket sized" transistorized radio, made in Japan of course, and was astounded to see components (mainly resistors) mounted perpendicular to the printed circuit board, with the "top" lead bent over and placed in a nearby hole in the PCB. I had been taught to...
  10. hevans1944

    Timer 555 voltage

    Jeff, you can connect two 9V batteries in series and share a common connection, with the 555 operating from one of them and your transistor operating from the two of them. This can be extended as far as you want to go by adding more batteries in series, but I would recommend not using more than...
  11. hevans1944

    Why is this Happening to Me?

    I often use a Vector pad cutter, a hand tool that creates a small circular island, or pad, surrounded by an annular ring of removed copper on an copper-clad bare board after you drill a pilot hole for the pad. Components are mounted through the hole in the pad and soldered in place, just as you...
  12. hevans1944

    What does Cooperative Multitasking mean?

    To fully appreciate RTOS, or any operating system, you have to appreciate why any operating systems is needed. The link that @Harald Kapp provided is an excellent introduction to RTOS. After I visited it, I realized that it is no longer necessary to use assembly language to write efficient...
  13. hevans1944

    Ignition Coil Driver Questions

    @WHONOES would like to know the ECU input impedance to make sure his pulse circuit can drive it. I don't know diddly about automotive ECUs either... the last car I actually worked on was my 1968 Mercury Cougar XR7, and it barely had controlled exhaust emissions that met 1967 standards. It did...
  14. hevans1944

    Ignition Coil Driver Questions

    Not sure why you want to 'scope the output? The pulses at the 220 VAC winding are rectified and filtered in @WHONOES test circuit, so without much loading of that output all a 'scope should reveal is a constant DC level. Were you planning to use the pulses developed by the circuit, adjusting...
  15. hevans1944

    Detecting horizontal position

    Well, it sure as hell screwed up their English. It's too bad neither Australia nor the USA had territorial ambitions in India at the time. OTOH, it's a "good thing" that English (veddy British version, eh wat?) is their official second language, because most folks have no interest in learning...
  16. hevans1944

    Differential Op-Amp

    @kamalmouawad: You have provided an application circuit that uses an "ideal" op-amp to convert the differential signals VI1 and VI2 to the single-ended output signal Vo, referenced to ground. This circuit is commonly used with two other op-amps to create an instrumentation amplifier with...
  17. hevans1944

    What does Cooperative Multitasking mean?

    A real-time opeerating system (RTOS) never implements cooperative multitasking. It must implement pre-emptive multitasking with predictable and known latencies in the time required for task switching. In other words, it must be deterministic. It is particularly important that the interrupt...
  18. hevans1944

    60 GHz rf meters

    “Facts, schmacts. You can use facts to prove anything that’s even vaguely true,” Homer Simpson Waiting for rebuttal from Sheldon Cooper.
  19. hevans1944

    Ignition Coil Driver Questions

    Wow! That is very rural. May we ask where in Siberia that you live?
  20. hevans1944

    Ups keeps tripping the CB

    I am gonna guess it's an AOG (Act Of God) that proved your UPS really isn't. Was there any lightning activity near the power line coming into this UPS? Nearby cloud-to-ground strikes can induce severe spikes on the power line, enough to cause the MOV to short-circuit and blow the fuse. That is...
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