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  1. hevans1944

    How To Annoy Those Helping You Out

    If the member you are referring to was me, I didn't get any of those memos.o_O "Rubbish text"? Whazzat? Examples please. 100 words or less.:D Hop
  2. hevans1944

    Feedback loop for constant voltage amplifier. Simulated Aircraft Power.

    To control the AC output amplitude you will have to control the amplitude of the signal generator input to the power amplifier. That generally means rectifying and filtering the AC output to create a DC feedback signal. You subtract this DC signal from a DC reference (control) signal to create...
  3. hevans1944

    Back from the Dark Side

    Good to see you again Señor Lopez! Maybe you can also now import a few electronic goodies from your Northern Neighbor?:D
  4. hevans1944

    mesh

    Yeah, but is that still a reason to go out and get pie-eyed with the consumption of gallons of tequila while stuffing down a ton of tacos? Oh, well, why not...:cool:
  5. hevans1944

    Using 2 Sevent Segment to display only 0-15 decimal

    Yes, you are right, but not just one "ic logic gate" will suffice, you will need several gates... unless you happen to have on-hand an EPROM (Electrically Programmable Read Only Memory) and the means to program it using the values in your truth table as the "memory data". IF you happened to have...
  6. hevans1944

    Zeroing out a LM317 reference voltage with a zener - PSU build

    It's called a "common mode" choke. It suppresses switching transients from inside the UPS getting back out on the power line.. either hot or neutral. We use them in amateur radio coaxial transmission lines to suppress "common mode" currents that travel back on the outside of the coaxial cable...
  7. hevans1944

    Using 2 Sevent Segment to display only 0-15 decimal

    Using @dorke's block diagram in post #16 above you must have a "black box" labeled Decoder that has four inputs that represent the bits on your binary counter. The Decoder has two sets of outputs: 4-bits for the MSD (Most Significant Digit) and 4-bits for LSD (Least Significant Digit). Each of...
  8. hevans1944

    Clean square waves using a 555 timer?

    The guv'mint would open that puppy up and look at the die if someone tried to sell it to them as a "genuine TI" part... well, at least if it was being sold in substantial quantities for use by the military or NASA. At my previous employer we sold a machine that could remove that epoxy...
  9. hevans1944

    Explain this circuit: Digital linear PSU

    @AnalogKid, thank you for correcting my analysis of the hand-drawn circuit that was posted above. It does provide negative feedback by virtue of the phase inversion at the collector of T5, and I failed to notice the change from a Szilaki pair (PNP and NPN) to a Darlington (NPN and NPN)...
  10. hevans1944

    How To Annoy Those Helping You Out

    Ah wisht ah cud spik hear with an ack-cent.
  11. hevans1944

    Clean square waves using a 555 timer?

    If you can believe this Google search result, and aliexpress.com, it's an original Texas Instruments part.
  12. hevans1944

    Oring of two Clocks

    The re-triggerable one-shot circuit is analog magic too! In my youth (age thirty or so) I eschewed one-shot multi-vibrators like the SN74123 because I perceived they weren't "truly digital" logic circuits. Fortunately, I soon got over it, which enabled me to also embrace the wonders of the...
  13. hevans1944

    Oring of two Clocks

    You could perhaps apply B to a re-triggerable one-shot multivibrator that will disable A and enable B when B is present to trigger the one-shot. Use the one-shot Q and /Q outputs to enable two fwo-input NAND gates, with the Q output enabling B and the /Q output enabling A. Combine the two NAND...
  14. hevans1944

    Where can I simulate "MAX1747"

    Maxim Integrated Circuits has a SPICE program available for free download, but you have to register on their website. Guess what: it does NOT include a model for the MAX1747! Go figure. One reason might be this component is at the end of its life cycle and is not recommended for new designs. It...
  15. hevans1944

    How is this Possible

    If you are really trying to learn, then learn how to "reverse engineer" your power supply and produce your own schematic. Then tale a picture of that schematic you have created from scratch and post it here for our comments.
  16. hevans1944

    Zeroing out a LM317 reference voltage with a zener - PSU build

    That is a good find. But it looks pristine! Are you sure it is not repairable? Sometimes the only thing that fails in a UPS is the gel-cell battery pack.
  17. hevans1944

    How is this Possible

    I am not a moderator, but I do post here and try (to the limits of my patience) to help newcomers. A picture (photo or schematic) really is worth thousands of words, unless you happen to be a particularly good wordsmith. And even if you are good at expressing ideas, concepts, and problems using...
  18. hevans1944

    Current up to a node?

    A node is a point where two or more wires come together. If you place a point on a wire, that point becomes a two-wire node... a trivial construct. If you place a point where three (or more) wires are connected in common, then that becomes a three (or more) wire node. And so on, for as many...
  19. hevans1944

    RC charging and discharging

    And all of this is assuming the bottom lead of the capacitor is actually connected to something, instead of hanging open in air as shown on the drawing.
  20. hevans1944

    Current up to a node?

    Current is measured at a point in the circuit, meaning that you would cut the circuit at the point and insert your ammeter there. Please do not confuse the points labeled on your diagram with nodes. KCL says all the current entering a node is equal to all the current leaving the node. This is a...
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