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  1. hevans1944

    Car Battery Powered House Ideas, Questions

    There are several scenarios that could by regarded as apocalyptic. One of the most plausable is a high altitude nuclear detonation (one or more) whose resulting ground-level EMP would disable the power grid and anything else electrical or electronic not hiding behind a Faraday shield. I think...
  2. hevans1944

    Greeting

    Welcome to Electronics Point. Newbies and noobs are welcome here.
  3. hevans1944

    Car Battery Powered House Ideas, Questions

    I think perhaps your are ignoring the cost of energy, measured and billed in kilowatt-hours. For example, I have a fairly typical house that uses on average about 1200 kWh of electricity every month. Some months it is more (summer with air conditioners running) and some months it is less (winter...
  4. hevans1944

    Wiring/Schematic help with SMC Solid State Auto Switch D-Y7NW

    The sensing mechanism is probably magnetic, which is irrelevant to how you connect the three output wires. This is an NPN current-sinking device. The brown wire should connect to the positive terminal of a 24 VDC power supply. The blue wire should connect to the common or "ground" terminal of...
  5. hevans1944

    Take your guess!

    This, or a similar company, has had a corner booth in a high-traffic aisle at the Dayton Hamvention® for at least two years in a row now, touting this "salt water battery system" as an emergency backup power source. I don't think they had many takers who "bought in" to their product, although...
  6. hevans1944

    Tesla 1000000 vac hf and electronics nearby

    All of the high voltage equipment I have worked on was well-shielded, and often insulated with a dielectric gas or liquid, so the electrical field was confined and did not have any effect whatsoever on nearby equipment. This is true in the static, steady state. If arc discharges are involved...
  7. hevans1944

    Interfacing joystick

    @SGW Don't bother trying to get to the valves to read whatever grime-encrusted information might be there. I don't think it is necessary to actually identify the solenoid valves by manufacturer and model number or part number. The fact that when 12 VDC is applied about 3A of current flows says a...
  8. hevans1944

    Spice Model for diode BAR43

    Here is a reference for a do-it-yourself model of this Schottky diode. Get the parameters from a datasheet or make an educated guess.
  9. hevans1944

    Invert PWM signal

    Oooh! It's not a program if it's Arduino, it's a sketch! Lemme see if the cookbook has a recipe for PWM inversion...
  10. hevans1944

    Battery Powered Vacuum repair

    As you can see in the photograph, the NiCd cells are clearly wired in series, daisy-chain fashion. So the terminal voltage, end-to-end, should be 1.2 x 5 = 6 V. You might want to check that with a digital multimeter (DMM) before throwing them away. I agree with you and the other poster (@Tha...
  11. hevans1944

    clever vibration motor driver?

    A minor inconvenience, that. But this is sometimes hawked as a "feature" for PWM because higher than steady-state voltages are often used, which result in greater starting torque at low duty cycles. It would not be uncommon to see a DC motor with a nominal rating of 4 V operated with a 40 V PWM...
  12. hevans1944

    Interfacing joystick

    Well, I am kinda stuck on the Flashlight Project because I haven't heard anything from Jeff since last May. I did finally get my PIC10F206 programmed to sip less than 10 μA current while still recognizing button presses, and turning off the flashlight LED for 1 ms every 135 ms if the LED is on...
  13. hevans1944

    Interfacing joystick

    @Gryd3 I don't think this would work. Op-amps require negative feedback to produce linear outputs. You cannot just apply voltage to the inverting or non-inverting inputs of op-amps and expect the output to be anything other than fully at one limit or the other. But, sketch up a schematic and...
  14. hevans1944

    clever vibration motor driver?

    Wow! Looks like you have thought this out pretty thoroughly and have done your homework. Very conservative design. Are you sure there is anything any of us here can contribute? Thank you for posting this.
  15. hevans1944

    Position of one device relative to another.

    Yes it would. And to think, James Clerk Maxwell figured it all out in 1873 and published equations explaining it all, from DC to Light. Of course Maxwell used quaternions in his explanation, which are basically incomprehensible to ordinary mortals. So in 1881 Oliver Heaviside trashed all that...
  16. hevans1944

    clever vibration motor driver?

    Nostalgia perhaps. I remember learning about R-2R ladder networks in the 1960s when we did everything with discrete logic. Large-scale-integration (LSI) of TTL was just beginning, CMOS logic was pie-in-the-sky, and if you wanted a DAC or ADC it had to be roll-your-own or purchase an expensive...
  17. hevans1944

    Interfacing joystick

    @SGW I did a little web surfing for R-2R ladder networks and DACs and found some inexpensive Bourns thick-film R-2R components readily available. These would require external transistor switches to select which elements are enabled and disabled to form a voltage-divider feedback network to set...
  18. hevans1944

    Position of one device relative to another.

    Pulse doppler IR means a rapidly pulsed infrared emitter, typically a laser diode, that produces range information from the round-trip time of the pulse and rate of closure (or separation) from the doppler frequency shift of the return pulse, usually homdyned on a fast infrared detector. Radar...
  19. hevans1944

    Building a time delay relay circuit with 555 timer

    Hmm. That would help to explain why the best meal of the day at Kincheloe AFB in the Upper Peninsula of Michigan was breakfast SOS and re-constituted orange juice. Well, except for the troops pulling alert duty in a bunker on the flight line, ready to fly in ten minutes or less, with a full boat...
  20. hevans1944

    clever vibration motor driver?

    I can appreciate that design philosophy. I also try to avoid unnecessary mechanical and electrical noise in my designs. I don't know much about DC motors (other than stepper motors) from practice. The fans used to cool the CPUs in my computers are very quiet and use brushless DC motors. Whatever...
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