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  1. hevans1944

    Help with RS485

    I apologize for joining this discussion so late in the game, but it appears that the Dallas Semiconductor One-Wire conversation has run its course. So, after reading @FuzzyWombatSoup 's last post, I thought I would jump in here. Starting over from the original post: Serial output ADC is a PITA...
  2. hevans1944

    Heatsink material question

    Iridite is a chemical coating applied to aluminum to prevent corrosion or improve electrical contact. The heat sinks were probably used with devices that were not insulated from the heat sink if the coating was Type 3 to Mil-C-5541F specifications. See this link. As for the "magnetic...
  3. hevans1944

    How does an RTD work?

    Alan, it appears that you may not have distinguished an RTD from a 4 - 20 mA RTD Transmitter. An RTD is typically made from plantinum wire with a resistance of 100 Ω at 0° C. Other values are possible, depending on wire diameter and length, but 100 Ω is typical. The resistance varies in a very...
  4. hevans1944

    Current control

    Could you please be a little more specific about your light? Manufacturer? Model or part number? Is it home-made from discrete LEDs? What is a "lid"? How did you determine the PWM controller was appropriate for your needs? The data sheet says it is for motor loads. No mention of current...
  5. hevans1944

    Help with aerial for channel 38

    Then you will probably be able to get by with a shorter Yagi with fewer elements... maybe just a dipole and a reflector element. There are advantages to the ten-element design: it is highly directional with a large front-to-back ratio, which helps minimize multi-path reflection reception...
  6. hevans1944

    Greetings all from the "Red Centre"

    Sounds like a neat place to visit... and maybe a place to practice for a manned Mars expedition? Nah, too pretty, too pristine, too primitive to be importing high-technology and spoiling the place. Those pics you posted are great! I just know you and your wife had a great vacation!
  7. hevans1944

    Cordless 1500 Watt Hand-held Blow Hair Dryer

    There is room for impressive as well as sedate operation. It all depends on the clientele. A shop in a mall, catering to walk-ins and low-budget (non-tipping) teenagers might attract such customers with a high-pitched winding-up sound, perhaps accompanied with flames temporarily shooting out...
  8. hevans1944

    Cordless 1500 Watt Hand-held Blow Hair Dryer

    I like this idea! :D The fumes are no problemo because we will use little hydrogen and oxygen canisters (like those used for pressurized CO2 carbonation seltzer bottles) for fuel! The only combustion product is water vapor (steam)! As for noise, that should be a relatively trivial problem to...
  9. hevans1944

    Help with aerial for channel 38

    Would this be TV Channel 38, broadcasting from Miami FL as WPMF, TV Azteca? I would think a ten element Yagi (one reflector, one dipole receiver, and eight director elements) specifically cut for Channel 38 (614 to 620 MHz) would be sufficient to receive TV Azteca. I have attached a...
  10. hevans1944

    Cordless 1500 Watt Hand-held Blow Hair Dryer

    Many thanks for the ideas so far. I had already suggested suspending the dryer from the ceiling and was shot down immediately: "Yeah, some salons do that (she could recall only ONE!), but if one stylist or hairdresser does it in any particular shop, they all have to do it." Ain't gonna happen...
  11. hevans1944

    Cordless 1500 Watt Hand-held Blow Hair Dryer

    I suspected as much, considering my experience with Li-ion cells in Craftsman power tools. I started out using 19 V so-called "Die Hard" nicads in my hammer drill/power screw-driver, but quickly changed over to Li-ion when Sears made those available for their Craftsman battery-operated tools. As...
  12. hevans1944

    Why is relay latching? :(

    I only suggested taking a 6V lantern battery to Radio Shack so you could use it to test their stock of piezo noise makers before buying one. The bozos there probably wouldn't let you do that... "pay before you play" policy at most retail stores, plus the stock is probably secured inside a...
  13. hevans1944

    Cordless 1500 Watt Hand-held Blow Hair Dryer

    My wife's daughter is a licensed cosmetologist here in Virginia Beach. She would like the hand-held blow dryer she uses constantly every day to be sans power cord, because the cord frequently gets tangled on either the chair or the customer while the dryer is being used. So, she asked her...
  14. hevans1944

    Cool circuit plotter with conductive ink

    Testing is good. Energy storage capacitors, i.e., capacitors specifically built to store an electrical charge and then discharge very rapidly into a switched load, come in a huge range of voltages, capacitance, and physical sizes. You would be amazed at what you can find stored away in...
  15. hevans1944

    Assistance with Transistor Theory

    Gee, someone tell the cell phone manufacturers, who have been using GaAs heterojunction BJT power transistors for quite some time now. I used to do ion implant isolation on gallium arsenide wafers patterned with thousands of 'em as microwave RF power integrated circuits (MMICs}. Did you not...
  16. hevans1944

    Assistance with Transistor Theory

    Can you say "Hopelessly ironic"?
  17. hevans1944

    Cool circuit plotter with conductive ink

    Umm... the guy said in the video "we have this big guy over here that's powering all the motors on this giant capacitor just to stabilize everything." And that is not such a ridiculously big capacitor. Might even be a little on the small side if it's less than 10,000 μF or so, depending on...
  18. hevans1944

    Assistance with Transistor Theory

    Hows about we discuss common-base RF linear power amplifiers? Those are pretty cool. And you can show off your acumen concerning decibel power-gain computations! I could use a little education in this area too. Merry Christmas, each and every one of you. I am in Virginia Beach with a house-full...
  19. hevans1944

    programming language

    I think all of those functions are supported in Windows through the Application Programming Interface and Microsoft's Software Design Kit (SDK). Last time I looked the SDK was oriented towards the C programming language, but you are free to use whatever you like just so long as the proper...
  20. hevans1944

    Why is relay latching? :(

    The piezo may not like the competition of working in parallel with the buzzer. I've never tried that. But those I have tried will make a LOT of sound when continuously powered up. Oh, well, mission accomplished: you can now hear if someone is at the door pressing the button! I have a front...
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