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  1. hevans1944

    74LS245 it doesn't work like i think

    WTF is Whiskey Tango Foxtrot, a currently popular meme, perhaps inspired by dance shown below:
  2. hevans1944

    74LS245 it doesn't work like i think

    So, for what exactly are you trying to use this integrated circuit? In other words: WTF are you trying to DO?
  3. hevans1944

    24volt 3000watt inverter

    Well, technically, it is a DC/AC POWER INVERTER. From labels on the device whose picture you posted, it was designed for use with photo-voltaic solar panels. However, another label identifies it as "CAR SMART POWER INVERTER USB 5V 6.8A (MAX)". Output is also specified to be 220/230V AC 50Hz, but...
  4. hevans1944

    24volt 3000watt inverter

    1500 watts (continuous) at 24 volts requires 62.5 amperes. This jumps up to 125 amperes if 3000 watts (intermittent) is required, say for starting a motor or initial surge current in a toaster. And this is the current required if the inverter is 100% efficient, which of course it isn't. I don't...
  5. hevans1944

    40 Floppy disks for...

    Me: "Well of course it was on sale! It's shoplifting if you walk out with it without paying for it!"
  6. hevans1944

    40 Floppy disks for...

    Isn't that what the pop-out CD ROM thingy is used for (with or without a CD ROM laying in the tray)? Hmmm. Of course that limits you to just one beverage container per CD ROM drive, a bit of a cramp if hosting a party... yeah, use them floppy disk thingies as drink coasters!
  7. hevans1944

    40 Floppy disks for...

    The lubricant on the disks inside has probably turned into a viscous goo. I would be very surprised if any of the disks would spin up, much less be readable and writable. I tried to recover some ancient disks I had by soaking them in isopropyl alcohol overnight and then re-lubricating their...
  8. hevans1944

    Inductor coil question

    Ooops! A newbie mistake. Thanks for the correction, @BobK, 23 turns it is (can't do fractional turns with a toroid core IIRC). So the OP should unwind just 9 turns of the the 32 original turns and then space the remaining turns evenly around the core. BTW, in the circuit shown 45 μH will...
  9. hevans1944

    What happen if I use EMI filter at more then specified current

    Well, if you have sufficient karma, it is possible to ignore the engineering specifications and operate the filter at any current you so desire. The only reason there are 2A and 10A continuous current models is to guarantee operation at those currents. There are coils (inductors) inside the EMI...
  10. hevans1944

    My IC chip isn’t working properly

    The 7400 series TTL ICs are a little more tolerant of open-circuited pins, which generally will float to a logic-high level for inputs. However, that's not guaranteed and poor design practice to depend on it happening. I too prefer to pull unused TTL inputs to the +5 V Vcc rail through a 1 kΩ...
  11. hevans1944

    Crystal sets - How do they work? :) (with real diodes)

    A diode, of any kind, conducts some current when forward biased and virtually zero current when reverse biased. That is all that is necessary for rectification of microvolt RF signals from the antenna.
  12. hevans1944

    Inductor coil question

    The new "replacement" inductor is 47 μH with 32 turns of wire on its core. Unwrap 15 turns, leaving 17 turns on the core, to bring the inductance down to about 25 μH. Spread those remaining 17 turns evenly around the circumference of the core using your fingernails. Cut to proper length, strip...
  13. hevans1944

    Solar Tracker

    While traveling between Dayton, OH and Denver, CO, I noticed a "solar farm" consisting of several acres of tall sunflowers. Those flowers would move their heads to follow the sun's path across the sky. Amazing thing, that! The sunflowers of course did not produce usable amounts of electricity...
  14. hevans1944

    Solar Tracker

    I neglected to consider the tilt of the Earth and its seasonal effect on the altitude of the Sun in the sky. So two-axis control may offer some advantages, albeit at increased cost and complexity, especially in locations like the Sahara Desert and equatorial locations with clear skies. It could...
  15. hevans1944

    Solar Tracker

    This is not a school. Members of Electronics Point already know at least some electronics and/or electrical principles. We meet here to exchange knowledge and ideas to further our own understanding, and to help others who may be having difficulty with some concepts. We help those who help...
  16. hevans1944

    Short

    What circuit? Where did the 45V come from? What is the ohmic value and wattage rating of the resistor? Why did you say "the other end is short to Ground"? Where else would you connect the other end? What is the value of the capacitor? What type is it? What is its working voltage rating? What is...
  17. hevans1944

    Want to fix my dinosaur: Who can fix a Sony CCD-FX730V?

    You might want to consider asking your question on this forum instead of here.
  18. hevans1944

    Electric Motor Conversion European - USA

    The motor may not care, but the actual wiring of the "reversal switch" may include a "frame ground" from the European installation. Connecting one of the two "live" 240 V AC 60 Hz mains lines to this "frame ground" is a recipe for disaster. I agree with @Minder that the "clicking" sound is the...
  19. hevans1944

    Microwave oven door hole - outer plastic panel

    I vote for this one, but just use duct tape (or duck tape if that's all you can find) as Steve recommended originally. It's just a cheap (maybe free) microwave... no need to make the "repair" look "professional" IMHO unless the OP wants to sell it.
  20. hevans1944

    Graph the output waveform of a MOSFET circuit

    This is a really dumb circuit for "explaining" how MOSFETs work. With Q2 turned off (gate input voltage is low) there is no conduction path for Q1 source because a load is not specified between Q1 source and ground. Although the gate of Q1 is connected to the drain and to +12 V, this does not...
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