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  1. hevans1944

    Circular?

    A few years ago we had a thread on a flashlight application that used a circular PCB that fit neatly into the base of the flashlight. Unfortunately, the project was a failure but the circular PCB was successful. The main problem that I see is routing the circular board outline after the traces...
  2. hevans1944

    Omnidirectional Ultrasonic transmitter

    @Sami Tabbakh: Are you ever going to tell us what you are trying to do? Or must we continue to play this guessing game of offering possible solutions that you then reject?
  3. hevans1944

    Some info I read re UV exposure resist undercutting, with questions..

    Indeed. The "magic chemicals" that the drilled board is dipped in to form a conductive film inside the vias can also be used to form a conductive film over both sides of a bare FR4 substrate. The electroplating of copper in the vias then also simultaneously plates a thin layer of copper onto...
  4. hevans1944

    Omnidirectional Ultrasonic transmitter

    It might help us to identify a product if you told us what you are trying to do. Omni-directional hand-held device isn't very informative. Is it hand-held in air? Underwater? At what distance must it provide an ultrasonic pressure wave? At what intensity? Is this a medical device? A weapon to...
  5. hevans1944

    How do I wire a BMP085 Barometric Pressure Sensor?

    Full pinout of Arduino Pro Mini can also be seen here: https://components101.com/sites/default/files/component_pin/Arduino-Pro-Mini-Pin-Diagram.png. But I like @Bluejets full-color PDF rendering better. :cool:
  6. hevans1944

    Help!

    @kellys_eye: I kinda think you should try changing the iris color of your avatar to suit your mood. Irish green comes to mind... or maybe a HIghland plaid motif? Moderators: Don't even think about banning @kellys_eye, even temporarily. His contributions to this forum take a HUGE load off other...
  7. hevans1944

    Some info I read re UV exposure resist undercutting, with questions..

    One possible remediation to the under-cutting problem during copper etching of the PCB is to use a slightly pressurized stream of heated etching solution directed perpendicular to the board via spray nozzles. IIRC, we purchased a heated ferric chloride tank from Kepro with this arrangement in...
  8. hevans1944

    Working with ESP&Vizual

    Perhaps something on the page at this link will get you started... This page seems to be particularly relevant to what you are requesting.
  9. hevans1944

    12 pulse rectifier output and filter circuit

    The OP isn't providing us with the whole picture. The link that was provided was to a single image from a paper that purported to describe various harmonic mitigation (suppression) techniques for three-phase power supply systems. Fortunately, unlike many published papers, this one isn't hidden...
  10. hevans1944

    Transistors amplification

    I hope that I have been careful over the past few years not to state or imply that the base current of a Bipolar Junction Transistor, or BJT, somehow magically controls the collector current because it simply doesn't. It is the forward biased base-emitter voltage that controls collector current...
  11. hevans1944

    Transistors amplification

    Gee, how many angels can stand on the tip of a pin? Maybe you should reconsider your "knowing" that a transistor amplifies current. It doesn't. So, no, a transistor cannot increase 5A to 10A.
  12. hevans1944

    Woo-Woo MOSFET switch question

    @Nikša: Although you have self-identified as in your post #5, your later response in post #16 seems to indicate some understanding of physics with a willingness to add electronics to your repertoire. Good for you. And having a multimeter is a good start. You can use it to rustle up some free...
  13. hevans1944

    Woo-Woo MOSFET switch question

    Yes. This is an enhancement mode MOSFET with an silicon dioxide (glass) insulated gate, so +5V or more on the gate terminal with respect to the source terminal should be enough to "turn on" the drain-to-source circuit if the MOSFET is rated to operate with 1000V between drain-terminal and...
  14. hevans1944

    Wiring for a emergency stop switch

    The type of switch you have shown appears to have momentary NC (Normally Closed) contacts, labeled 1 and 2, for the "0" or OFF switch, and momentary NO (Normally Open) contacts, labeled 3 and 4, for the "1" or ON switch. It requires a relay (or contactor) as @Minder indicated in his post #2...
  15. hevans1944

    Newbie 12v meltdown, please help.

    There are CCTV systems used by wildlife photographers and hunters that only consume insignificant amounts of power until a passive infra-red (PIR) motion sensor triggers them to record. Recording time can be either a predetermined fixed interval, or continuous if motion is detected. You might...
  16. hevans1944

    Newbie 12v meltdown, please help.

    Circuits consume as much current or "ampage" (to use your terminology) as they need, NOT the amount of current their power source is capable of providing. There would have been no problem if you had wired it with the correct polarity, no matter how much current the battery was capable of...
  17. hevans1944

    Newbie 12v meltdown, please help.

    Sounds to me like you reversed the polarity when you wired the motorcycle battery to the camera... a typical newbie mistake since you probably didn't check the polarity of the "220v to 12v 1000mA plug in adapter" with a multimeter before trying to substitute it with a battery. I am guessing...
  18. hevans1944

    Wire spool - what is it worth?

    A new 100-foot spool of Belden 8760 18 AWG twisted pair with Beldfoil shield is currently (06 May 2018) sold by Amazon for $97.00... but there were only 12 spools left in stock. A 5000 foot spool is a sizable amount, and if you are an electronics hobbyist, it is probably a lifetime supply. It's...
  19. hevans1944

    Heat shrink as water insulator

    There are several non-electrical approaches, none of which you are likely to be able to employ unless you have access of laboratory-grade equipment. The simplest method requires an analytical balance to perform a "before and after" weight measurement. You take your "test sample" as shown in...
  20. hevans1944

    Can Crusher - High School Physics Porject

    That's always the problem when experimenting with high-energy devices of any kind. Safe is very much a relative attribute. Anticipating, and allowing for consequences, helps to make things safer, but every time someone tries to make something "idiot proof" a better idiot comes along to defeat...
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