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  1. hevans1944

    Interesting circuit usb with 2 led lights with different brightness

    Yep Looks like you found it! You can duplicate the functionality of this lamp with a PIC μP or an Arduino if you want to get your feet wet with programming. This is typically done on a solderless breadboard. As far as schematics are concerned, Google could be your best friend for those. But...
  2. hevans1944

    A/D impedance PIC connected to RC circuit

    I had the same problem the other day. Kept getting an error message saying it couldn't upload my image file. My eventual solution was to load the image in Microsoft Paint, size it to 1024 x 768 pixels and then save the re-sized image under a different file name. The new image file uploaded just...
  3. hevans1944

    Interesting circuit usb with 2 led lights with different brightness

    What @Bluejets is saying is the tactile switch (and it IS a tactile switch) completes one (and only one) circuit that is an input bit for a microprocessor. A program in the microprocessor (or μP for short) "reads" and interprets the switch presses and then provides two output bits that turn on...
  4. hevans1944

    PIC A/D question

    Did you abandon this thread to start this one: https://www.electronicspoint.com/forums/threads/a-d-impedance-pic-connected-to-rc-circuit.291337/ ?
  5. hevans1944

    A/D impedance PIC connected to RC circuit

    As @BobK (quietly) said: SHOW US HOW IT IS CONNECTED! (shouting and emphasis mine because original poster doesn't appear to be paying attention) And to answer your question #4: No, nothing about your post appears to be correct. Capacitive reactance is not defined at DC, which by definition is...
  6. hevans1944

    Why relay contact stick even when power off?

    That would be a nice solution perhaps, but this is likely a commercial product with "programming" built in and modifications not supported by the manufacturer. Always fun to try hacking such things to "improve" their performance and/or reliability.
  7. hevans1944

    Why relay contact stick even when power off?

    The little blue varistor is a nice addition. Too bad though that no component values are given. Guess you buy it and try it, and for less than two bux maybe that's a bargain... sure can't build it for that price. Good find @Bluejets!
  8. hevans1944

    Why relay contact stick even when power off?

    It is a good set of component values to begin with. How well it works depends on factors, such as fan motor inductance, over which you have no knowledge or control, but give it a try. Make sure the capacitor voltage rating is adequate since it will have full line voltage applied across it when...
  9. hevans1944

    High Data Rate RF Link

    Most of my career was spent performing contract R&D work for U.S. Government sponsors. Everything we did was a one-off, a proof of concept that, if successful, was tossed over the transom to a real manufacturer the likes of Hughes, Northrop Grumman, Boeing, Raytheon, Texas Instruments and so on...
  10. hevans1944

    Why relay contact stick even when power off?

    \ Read @73's de Edd reply. You need to add a snubber across the relay contacts, or install a new relay, hopefully with better contacts. An RC snubber is a series-connected resistor and capacitor, placed across normally-open circuit contacts that are closed when you deliver power to the load...
  11. hevans1944

    Why relay contact stick even when power off?

    What is the purpose of RL1, RL2, and RL4? And what is the purpose of the three RC networks in series between the contacts of these three relays and the "Fan Connector" J2? Why is there no such network of resistors and a capacitor between the contacts of RL3 and the "Fan Connector" J2? Are you...
  12. hevans1944

    High Data Rate RF Link

    Thank you for your comments, @Nanren888. I visited your website and came away quite impressed with what is going on "down under," so-to-speak, in New Zealand. One of our best liked and most prolific contributors to Electronics Point went by the online moniker of @KrisBlueNZ, but he is now sadly...
  13. hevans1944

    High Data Rate RF Link

    For "ones and zeroes"? Why would you wanna add a clock to that? Besides, the OP stated: Self-clocking data protocols have existed for a very long time, so adding a clock appears to fall into this category. As does error-detection and correction. So, lets apply the KISS principle and just stick...
  14. hevans1944

    High Data Rate RF Link

    "The price of answer was to be chastised?" What did you mean by that statement? And what lesson do you think you learned? This isn't a teaching forum, and I wasn't trying to chastise anyone, just suggesting that you haven't been very diligent yet in seeking answers before posting here. I can...
  15. hevans1944

    High Data Rate RF Link

    A pair of Arduinos with Zigbee shields can implement a rudimentary, one-way, simplex data link, as shown on your sketch. Lots of information is available in various forums on how to do this. Learn to let Google be your best friend in finding possible solutions before coming here. With...
  16. hevans1944

    Design 3-step sequence circuit.

    You claim you know how to make a "sequence circuit using a transistor and a diode." Show us your schematic with parts call-outs and your explanation of how it works. A picture of a hand-drawn schematic is okay. Someone here will look at it and ask more questions. Until that happens, you answer...
  17. hevans1944

    Cavity resonator - construction?

    It is my understanding that commercial silver plating is a dip-process involving cyanide-based chemistry, heated tanks, and "trade secret" recipes that is not at all suitable to the thin layer of "spot" silver plating required for radio frequency conduction enhancement, which only requires a...
  18. hevans1944

    Cavity resonator - construction?

    MMMM! Resonate cavities at frequencies reachable by ordinary amateurs not having microwave-deep pockets. What's not to like, except maybe the unfamiliar theory-of-operation, where circuits appear to be dead shorts or grounded but really are not. I recall seeing the Dayton Amateur Radio...
  19. hevans1944

    Input power vs Output power in pro amps

    Indeed. A few years ago (late in the previous century), we were using electron-beam furnaces to evaporate magnesium oxide and allow the vapor to sublimate on a hastalloy stainless steel tape, supplied from a reel-to-reel in-vacuum dispensing system. In addition to the electron-beam furnace at...
  20. hevans1944

    Input power vs Output power in pro amps

    Geez! Have we regressed to the 1940s, simply replacing the venerable Williamson Class AB vacuum tube audio power amplifier with Class D MOSFET switched power amplifiers... all the while keeping the same hype and snake-oil salesmanship? As Little Beaver would say, "You betchum, Red Ryder!" And...
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