Search results

Search Forums New Posts
  1. hevans1944

    Bistable Multivibrator

    Here is a link to an Amazon page that has lots of image views, complete with on-screen magnifier, for what is branded as a Wrisky 1 Channel 12V Latching Relay Module with Touch Bistable Switch MCU Control The "part number" is Wrisky0386. No price is given, and Amazon says it is out of stock and...
  2. hevans1944

    Changing a positive and negative audio signal to positive only

    I don't think you actually need the "bias" supply, it's series resistor, and the 1N4148 diode with its cathode connected to ground. As shown, the "bias" supply simply forward biases D2 all the time, draining current from whatever 5V voltage source is provided by V2. The connection of D2 anode...
  3. hevans1944

    Can you identify this electrical piece of circuitry?, Needle in a haystack scenario.

    It's a driver board that contains hexagonal first-surface mirror facets used either to optically scan documents or to write images on a photosensitive film that carries the image, via electrostatically attracted toner, to the copy paper. The motor is missing, and precision bearings in the motor...
  4. hevans1944

    Video signal amplifier.

    I have been eye-balling the 4K TVs to see if I can see any significant improvement over our current1080p TVs, two of which we bought at truly exorbitant prices (although they were "on sale" at a "discounted" price) about five or six years ago. Prices have come down a lot, but except on screens...
  5. hevans1944

    Video signal amplifier.

    I suppose the statue of limitations applies for this answer... so, yes. I subscribed to early cable television in the 1960s, provided on poorly-shielded coaxial cable by Time Warner, who has a monopoly on cable TV in Dayton, Ohio. Reception of their frequency-division multiplexed TV channels...
  6. hevans1944

    Video signal amplifier.

    It is unfortunate that you found this particular rodeo about forty years too late. I suggest you find some articles in the Internet archives that describe the "how" and "why" of NTSC analog video. DC levels in the video are extremely important. It was fascinating to play with this stuff in the...
  7. hevans1944

    How to determine current

    Are you sure the three 1.2V NiMH cells power the LED directly? Are there NO electronics between the battery bank and the lamp? If this is a "white light" high-wattage LED, then 3.6V may not be enough to drive it to full brightness. OTOH, connecting the LED lamp directly across these three cells...
  8. hevans1944

    Photon detectors

    I haven't performed the double-slit experiment with anything that could "spy" on what happens if there is something that records or detects a single photon exiting one of the two slits. However, "common sense" might say that if a photon is detected, then that's a photon that cannot experience...
  9. hevans1944

    Breadboard lead size

    Things are getting tough all over the world. Probably a result of a paradigm shift in World Economy that says a country can tax itself into prosperity. Here in Florida we worry about sky-rocketing food costs, across the board on everything. Florida touts its "no income tax" but taxes everything...
  10. hevans1944

    Breadboard lead size

    Since Radio Shack folded its tent, here in the States we usually have to buy inexpensive Chinese-sourced stuff from Amazon or eBay or some other Internet retailer. Of course, if you can afford it, there are still some American on-line retailers too, and I do purchase small onsie-twosie...
  11. hevans1944

    Photon detectors

    Hi! I am aware of your fertile imagination as well as your Asperger's autism. One of my grandchildren "suffers" the same thing and we think perhaps one of his younger sisters does too. In both siblings it is "mild" and they both have "discovered" or invented other ways to communicate. It's a...
  12. hevans1944

    Photon detectors

    @CommanderLake: You just might be in a little over your current level of competence on this one. Avalanche conduction can occur when a diode is reverse-biased sufficiently. It is distinguished from ordinary reverse-biased zener conduction by being a "positive feedback" mechanism that can...
  13. hevans1944

    Breadboard lead size

    Not sure what length of 22 AWG that 500 gm will provide, but here is a vendor that will sell spools with 25 feet up to 5000 feet for what I think are reasonable prices... a 100 foot spool costs $11.40 plus shipping. From my own personal experience, that represents a "lifetime" supply although...
  14. hevans1944

    Do I need a heatsink? How big?

    Thanks for the excellent links... to a source in Australia, no less! How in the world did find these from all the way in Holland? And don't tell me Google did all this. Methinks you and the @Audioguru have a lot in common.:D
  15. hevans1944

    A cb radio not working after being sent in for modification

    Hmmm. I would never do what you did: blindly return a used item to the manufacturer without asking for permission to do so, and before obtaining a Return Authorization Number or letter or similar document showing proof that the return was authorized and that the item would be accepted by the...
  16. hevans1944

    Senior Project

    Gorilla Glue usually works for me when I am attaching stuff.
  17. hevans1944

    Understanding a regulator circuit with MOSFET and Zener-Diode

    Well, I guess plenty of folks are likely to observe the thread now that newbie @fawad928 has gone and bumped it. Why do these old threads keep re-appearing so often? I've been "burnt" many times responding to an outdated thread, simply because i failed to notice the dates of the previous...
  18. hevans1944

    WheatStone bridge

    When using Kirchoff's current law to analyze a circuit, you need to identify closed loops that will contain currents and (in this case) resistances to dissipate those currents. You pick arbitrary directions for the currents and let the polarity signs across the resistances be according to the...
  19. hevans1944

    Frankenstein's Components.

    Look closely at the left hand of the person feeding the flux-coated welding stick into the weld puddle. How does he not suffer some sort of severe burns with no gloves, unbuttoned long shirt sleeves exposing his forearm to the heat and ultra-violet arc emissions, and probably no eye protection I...
  20. hevans1944

    PIC A/D

    Yep! Tell us what you are trying to DO then let us suggest one or more ways to do it. What PIC are you using? Why can you not upload a schematic? A hand-drawn schematic is preferable to none at all. What is the part number of your photo-transistor? Have you considered using a reverse-biased...
Top